ESR Meter - New updated version - RC Groups
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Feb 27, 2015, 03:52 AM
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New Product

ESR Meter - New updated version


ESR METER - NEW UPDATED VERSION

The ESR meter has now been updated to produce a lot more information so that it is now more of a Lipo Analysis meter than just an IR meter.

In addition to reading pack and cell voltage and IR (accurately!) the meter now gives direct readouts of charge state, practical "C" rating and maximum safe current drain for long pack life. Other new features include a low cell voltage warning and an over range limit warning.

The other good news is that the changes are software driven so that there is no price increase and existing owners will be able to update their meters at nominal cost providing they can use a soldering iron – only two joints to re-solder!

I would like to pay credit to Phil Green (Phil_G on RCG) who has worked miracles with the software – not being a software man, I am amazed at what he has achieved given the limitations of a 14 pin chip and a single control button.


I will post again later with details and cost of the update kit for owners of the original meter.

UPDATE : See https://www.rcgroups.com/forums/show...&postcount=125
Wayne
Last edited by Wayne Giles; Nov 15, 2016 at 11:05 AM. Reason: Production restarted November 2016
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Feb 27, 2015, 05:11 AM
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ggcrandall1's Avatar
Wayne,

Thats a great upgrade. I have one of the originals and am looking forward to the upgrade instructions for my unit.

Glen
Feb 27, 2015, 08:21 AM
Frankenstein recycled packs
rampman's Avatar
YEAH!!!
You mean I will no longer need to use my smart phone to calculate the pack max discharge amps at the flying field or in my shop? [img]rampman dancing[/img]
I will either sell my original and buy new or upgrade the old. I LOVE these meters and they just got better.

Rick
Feb 27, 2015, 09:43 AM
Registered User
DonA's Avatar
I use my ESR meter all the time and this will just make it more useful. Looking forward to the upgrade option.

Don
Feb 28, 2015, 07:29 AM
Rocky Mountain High
I have used your meter for my business since it was first introduced to the U.S. market. Very good product. Will upgrade when available.
Mar 01, 2015, 05:12 AM
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Bill Glover's Avatar
Excellent - I will definitely take the upgrade kit when it's available!
Mar 01, 2015, 07:55 AM
Registered User
In Cell Mode does it provide IR, etc. readings for the individual batteries?
Bill
Mar 01, 2015, 05:02 PM
Registered User
Glen, Rick,Don, Marvin and Bill,


Sorry for delay in replying. The update kits should be available in about a week and I will post details then, hopefully with photos to demonstrate how easy the updating process is.

Quote:
Originally Posted by ko4nrbs
In Cell Mode does it provide IR, etc. readings for the individual batteries?
Bill
Bill,

I assume you mean individual cells (?). In which case the answer is 'Yes'
When you plug the search lead into any two adjacent sockets in the balance connector, it automatically switches to 'Cell' mode and provides readings of the characteristics of the cell corresponding to those two sockets.

Wayne
Mar 02, 2015, 10:15 PM
Registered User
You guys are going to LOVE the updated version 2.0 controller! I spent ~10 minutes upgrading mine tonight and my ESR Meter is now even more useful than I could have ever imagined. Simply key in the capacity and it does all of the rest.

Nice to be able know maximum recommended current draw at the field without having to enter data into the online tool or spreadsheet. I do have the Excel database file on my Android phone to do field calculations but the upgrade is even more handy.

Of course, don't let this nice upgrade discourage you from compiling your data and uploading to the Database thread.

Highly recommend the Version 2.0 upgrade when Wayne releases it!!

Thanks Wayne for your continuous improvement to your indispensable ESR Meter!

Mark
Mar 04, 2015, 12:54 PM
Registered User
UPDATE PACK NOW AVAILABLE FOR ORIGINAL ESR METER

I now have some update packs to enable owners of the original ESR Meter to bring them up to the latest Analysis specification. Standard meter only NOT the HiRes version.

Prices are :-

----------------------------US Dollars---------UK Pounds------------UK Pounds

Update Pack Price------$12.50---------------£8.00---------------------£8.00

Post and packing--------$6.50-----------------£1.00---------------------£3.30
------------------------(To USA & ROW)-------(To UK)----------------(To Europe)

Sorry about postage price, but it is at cost - not marked up!

To see how easy it is to update your unit I have attached a set of instructions below.

I will answer any queries here or by PM .
PM me if you want one and I will return an e-mail address for Paypal.

Wayne
Mar 04, 2015, 01:21 PM
Rocky Mountain High
PM for upgrade
Mar 04, 2015, 01:44 PM
Registered User
Bill Glover's Avatar
PM sent.
Mar 04, 2015, 02:19 PM
Boat racing enthusiast
Pescador's Avatar
PM sent as well
Mar 04, 2015, 02:37 PM
Registered User
Does the upgrade include a new label for the front?
Mar 04, 2015, 02:54 PM
Registered User
Quote:
Originally Posted by Ohmic
Does the upgrade include a new label for the front?
Not normally. I considered it but the problem is that there is no margin on the sheets between images so cutting one out scraps those around it.
If you really need one however, make a note when you order and I will put one in.

Wayne
Mar 04, 2015, 03:11 PM
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DonA's Avatar
PM sent
Don
Mar 06, 2015, 02:27 PM
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Bill Glover's Avatar
Did my upgrade this evening - no problems, all works very nicely

One question though ... have you got the table of cell voltage vs state of charge it uses? I've seen various versions in the past, all slightly different. The ESR gives a higher percentage charge figure (for a given cell voltage) than the Hyperion tester I have ... I assume there's no definitive answer that suits all makes of cell?
Mar 06, 2015, 04:33 PM
Registered User
Quote:
Originally Posted by Bill Glover
Did my upgrade this evening - no problems, all works very nicely

One question though ... have you got the table of cell voltage vs state of charge it uses? I've seen various versions in the past, all slightly different. The ESR gives a higher percentage charge figure (for a given cell voltage) than the Hyperion tester I have ... I assume there's no definitive answer that suits all makes of cell?
Bill,

Glad to hear all is OK with your update.
Regarding the % charge state v Cell voltage, it was a combined effort using Mark Forsyth's table with contributions from John Julian and Hoppy and was generated last year for the Single Cell meter. We were all aware of the variations, presumably because of different battery formulations, but tried to produce a compromise to cover most average LiPos.
I think any such table can only be a guide rather than a precise function.

Wayne
Mar 06, 2015, 07:52 PM
Registered User
pm sent

Gadget
Mar 07, 2015, 06:21 AM
Supersonic Engineering
GordonTarling's Avatar
Got my upgrade yesterday, the day after ordering - many thanks Wayne!
I've just installed it and it works well.
One tiny suggestion for the next version - when measuring the individual IR of cells, the screen display is retained when the cell being read is disconnected and remains there when the next cell is connected until the button is pressed. My feeling is that it would be better if the display could be blanked or made to read --- until the button is pressed again. It's still a great piece of kit though!
Mar 07, 2015, 06:34 AM
Registered User
Quote:
Originally Posted by GordonTarling
Got my upgrade yesterday, the day after ordering - many thanks Wayne!
I've just installed it and it works well.
One tiny suggestion for the next version - when measuring the individual IR of cells, the screen display is retained when the cell being read is disconnected and remains there when the next cell is connected until the button is pressed. My feeling is that it would be better if the display could be blanked or made to read --- until the button is pressed again. It's still a great piece of kit though!
Gordon,

I will ask Phil to look at the possibility.. The potential problem is lack of space on the PIC. The penultimate version had just 27 bytes left spare in the memory but did not read cell voltage if it was below 3.20V - it just gave a warning. Final version does read actual cell voltage before giving the warning but Phil told me there are now zero bytes left.

Wayne
Mar 07, 2015, 12:51 PM
RC Keeps Me Sane
DanBo3D's Avatar
PM'd for upgrade with label. THANKS!!!!
Mar 08, 2015, 05:07 AM
Supersonic Engineering
GordonTarling's Avatar
Quote:
Originally Posted by Wayne Giles
Gordon,

I will ask Phil to look at the possibility.. The potential problem is lack of space on the PIC. The penultimate version had just 27 bytes left spare in the memory but did not read cell voltage if it was below 3.20V - it just gave a warning. Final version does read actual cell voltage before giving the warning but Phil told me there are now zero bytes left.

Wayne
Wayne,

I did wonder if lack of memory might be the reason. It's not a huge problem and it's a very useful piece of kit to have anyway. Perhaps consider it for the 'MkII'.
Mar 08, 2015, 07:14 AM
Registered User
Quote:
Originally Posted by Bill Glover
Did my upgrade this evening - no problems, all works very nicely

One question though ... have you got the table of cell voltage vs state of charge it uses? I've seen various versions in the past, all slightly different. The ESR gives a higher percentage charge figure (for a given cell voltage) than the Hyperion tester I have ... I assume there's no definitive answer that suits all makes of cell?
Bill,

Here is a more definitive answer to your question. Its not a table but is the plot the software was developed from. Thanks to John Julian who flogged away discharging packs and plotting all the voltages. You can see that they all follow the same general trend with minor differences so that the best the possible accuracy must be to follow the average centreline of these plots.

Sorry for delay but I did not want to post without permission from JJ.

Gordon,

That WAS the Mk II, actually it was about the Mk VI, but we can try for a MkVII.

Wayne
Mar 08, 2015, 09:22 AM
Registered User
Bill Glover's Avatar
Quote:
Originally Posted by Wayne Giles
Bill,

Here is a more definitive answer to your question. Its not a table but is the plot the software was developed from. Thanks to John Julian who flogged away discharging packs and plotting all the voltages. You can see that they all follow the same general trend with minor differences so that the best the possible accuracy must be to follow the average centreline of these plots.

Sorry for delay but I did not want to post without permission from JJ.
That's perfect - many thanks Wayne. I wasn't pushing for the data as I did appreciate it was the result of testing and input from other people. I have various tables and curves in Excel but they are derived from old test results I've seen, and are quite possibly not so applicable with today's cells. I mentioned that my commercial pack checker gives lower percentage charge figures - I'll probably continue to use that in the field as it obviously errs on the conservative side (not a bad thing). But it's nice to be able to get more accurate info. when I need it
Mar 08, 2015, 01:36 PM
Registered User
Bill Glover's Avatar
As an aside ... I made a new label for mine today by downloading one of the pics. in post #1, cropping to just the label part, and printing it onto clear inkjet vinyl. I figured that was quicker than trying to work out what the font was?!
Mar 08, 2015, 04:55 PM
ancora imparo
jj604's Avatar
Bill, out of interest I plotted results from three of the Capacity checkers I happen to have aginst a couple of the packs that I tested.

The Hyperion Sentry and my (original Japanese) Cellmeter8 give good agreement. The AEO-RC meter reads significantly lower.

The two pack curves were chosen as they are representative of the results I was getting from the LiPos. One seems fairly smooth throughout the range, the other shows a characteristic voltage hump at about 85% charge. This was true of most of the 3S 2000 packs I tested. I have not carried out a similar test on other sizes of packs.

John
Quote:
Originally Posted by Bill Glover
That's perfect - many thanks Wayne. I wasn't pushing for the data as I did appreciate it was the result of testing and input from other people. I have various tables and curves in Excel but they are derived from old test results I've seen, and are quite possibly not so applicable with today's cells. I mentioned that my commercial pack checker gives lower percentage charge figures - I'll probably continue to use that in the field as it obviously errs on the conservative side (not a bad thing). But it's nice to be able to get more accurate info. when I need it
Mar 08, 2015, 06:01 PM
Registered User
Bill Glover's Avatar
Just out of interest I tried a random 3S 8000 pack tonight.

Multimeter:

Cell 1: 3.83V
Cell 2: 3.83V
Cell 3: 3.84V
Pack: 11.51V

Hyperion Sentry:

Cell 1: 3.836V, 46%
Cell 2: 3.841V, 46%
Cell 3: 3.846V, 48%
Pack: 11.51V

ESR Meter

Cell 1: 3.85V, 54%
Cell 2: 3.85V, 54-56% (flickering rapidly between the two)
Cell 3: 3.85V, 56%
Pack: 11.48-11.52V (flickering rapidly between the two)

So as mentioned the Hyperion is 'pessimistic' on state of charge, which is OK. And the ESR does a decent job on voltage, although IIRC it's not really designed for this. Great to have the 'real C rating' function now (13C reported, vs 30C on the pack label!).
Mar 08, 2015, 06:02 PM
Registered User
Bill

I will look at putting a file of the label on the thread so that people with updates can print a new label using standard software.
I use polyester labels which must be laser printed and standard Avery label software. The problem with inkjet printing is that it is not waterproof.

John,

That 'hump' you see in the charge curve is also present in CC discharge curves and seems to occur at a particular voltage level, so it is a mirror image of the charge curve appearing at about 85% charge as you say. It is more prominent in low rate discharges, presumably it is swamped in heavy discharges so that it is hardly noticeable.

Wayne
Mar 08, 2015, 06:16 PM
Registered User
Bill Glover's Avatar
Quote:
Originally Posted by Wayne Giles
The problem with inkjet printing is that it is not waterproof.
That's true but after printing I add a top layer of either Sellotape Diamond clear tape or a thin coat of aerosol acrylic lacquer (depending on the size of the label). Sadly I no longer have a laser printer!

A file with the text would be a great addition to the thread
Mar 13, 2015, 10:16 AM
Registered User
wayne, Please could you let me know how to order your ESR update kit. Stan Gilbert
Mar 13, 2015, 10:39 AM
RC Keeps Me Sane
DanBo3D's Avatar
Quote:
Originally Posted by Abington Flyer
wayne, Please could you let me know how to order your ESR update kit. Stan Gilbert
Send him a PM from one of his posts here and tell him you want the update.
He'll reply with his ppal email for payment.
Mar 13, 2015, 12:52 PM
Registered User
Quote:
Originally Posted by Abington Flyer
wayne, Please could you let me know how to order your ESR update kit. Stan Gilbert
Stan: I have sent you a PM with my e mail address to enable you to send the funds via Paypal.

Wayne
Mar 14, 2015, 06:10 AM
Registered User
hi Wayne,

Could u check your pm. I had messaged u. tks.
Mar 18, 2015, 02:04 PM
RC Keeps Me Sane
DanBo3D's Avatar
Got my upgrade today, installation was smooth and easy.
In fact I did it without any desoldering, carefully pulled the circuit board away from the screen pins and I had plenty of room to remove and install the new chip.
Works perfect and the new features are a treat.
Thanks for making a great product even greater!!!
Mar 18, 2015, 03:25 PM
Boat racing enthusiast
Pescador's Avatar
Upgraded mine as well today, no problem I had a solder sucker that worked great.
Thanks Wayne!
Mar 18, 2015, 03:43 PM
Frankenstein recycled packs
rampman's Avatar
Upgraded mine yesterday. Only had a very old worn out 2S 4000 with total IR of over 80 so I could not test (play) with all functions at work. Remember those gifts we received as a kid but could not play with due to rain/snow/cold... ? Yulp, I had to wait 5 hours till I got home.
Now it is like the HK IR meter but an accurate version.

Rick
Mar 18, 2015, 04:06 PM
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ggcrandall1's Avatar
Quote:
Originally Posted by DanBo3D
Got my upgrade today, installation was smooth and easy.
In fact I did it without any desoldering, carefully pulled the circuit board away from the screen pins and I had plenty of room to remove and install the new chip.
Works perfect and the new features are a treat.
Thanks for making a great product even greater!!!
I was waiting for solder sucker to arrive when I read your tip. I just installed mine using your technique. It worked like a charm. The whole process took less than ten minutes. Thanks for the tip.

And Wayne, thank you for a great product.

Glen
Mar 18, 2015, 04:18 PM
Registered User
ggcrandall1's Avatar
What an eye opener. I have a 3S 2450mah 70C pack that reads:
Pack - 15.6mohm, Cell 1 - 3.64mohm/26C, Cell 2 - 3.76mohm/25C, Cell 3 - 3.76mohm/25C

I got similar results from several other packs.

I wonder if anyone has measured a pack that lives up to the specs?

Glen
Mar 18, 2015, 04:49 PM
Registered User
Quote:
Originally Posted by ggcrandall1
What an eye opener. I have a 3S 2450mah 70C pack that reads:
Pack - 15.6mohm, Cell 1 - 3.64mohm/26C, Cell 2 - 3.76mohm/25C, Cell 3 - 3.76mohm/25C

I got similar results from several other packs.

I wonder if anyone has measured a pack that lives up to the specs?

Glen
Glen,

I know the Lipotool is conservative, but any pack showing 25C is Good pack.
I'm sure you know that any pack over a real 40C does not exist!

Wayne
Mar 19, 2015, 06:13 PM
Registered User
icicles's Avatar
Just received my new chip, took 5 minutes to do the upgrade.
Fantastic tool.
I think every electric flyer needs this meter. Sure takes the guesswork out of your batteries.
Thanks for an awesome product
Chris
Mar 19, 2015, 08:52 PM
Registered User
john4565's Avatar
Great work on the upgraded firmware Wayne; it's absolutely brilliant.

The replacement of the PIC only took 10 minutes. Delivery from the UK to Australia only took two weeks, but I was amused to find that aussie customs had opened up the parcel and left me a note inside saying they found no "drugs, guns or other weapons" in the packet, which was good news I guess
Mar 20, 2015, 10:30 AM
Registered User
Quote:
Originally Posted by john4565
Great work on the upgraded firmware Wayne; it's absolutely brilliant.

The replacement of the PIC only took 10 minutes. Delivery from the UK to Australia only took two weeks, but I was amused to find that aussie customs had opened up the parcel and left me a note inside saying they found no "drugs, guns or other weapons" in the packet, which was good news I guess
John,

Thanks for positive response .

Would you believe I sent a meter to Oz some time back which arrived within 48hours! Perhaps you should complain to Aussie customs for holding it up.

On second thoughts perhaps not - a meter I sent to the USA was attacked by US customs who drilled a hole through the display, presumably in case some white powder ran out - no comeback of cause; senders risk . Too much trouble to undo two screws and open the meter to look


Wayne
Mar 20, 2015, 10:56 AM
No Guts, No Glory
timmybeetle's Avatar

received update IC


HI

Received today update IC.
Easy install, just as described in update instruction.
Took 5 minutes, very happy with this update.
Thanks to Wayne, Mark and John

grts Hans
Mar 20, 2015, 11:30 AM
Registered User
Hi Wayne, Received my update in the mail today. Looking forward getting it in my meter. Thank you, Stan
Mar 20, 2015, 02:22 PM
Registered User
Bill Glover's Avatar
Wayne - any thoughts on providing a simple upgrade kit for the 1S / low current mods:

https://www.rcgroups.com/forums/show...&postcount=364

Although we can probably all source a switch and a power connectors easily enough not many places will sell individual resistors / diodes of the right spec.?
Mar 20, 2015, 05:52 PM
Registered User
Quote:
Originally Posted by Bill Glover
Wayne - any thoughts on providing a simple upgrade kit for the 1S / low current mods:

https://www.rcgroups.com/forums/show...&postcount=364

Although we can probably all source a switch and a power connectors easily enough not many places will sell individual resistors / diodes of the right spec.?
Bill,

The problem is postage cost. The software update package weighs 40grams and still costs £4 + cost of packaging to send to most of the world. The components for the low current or the 1S update cost less than 25p so how can I charge £5 for 25p's worth of components?
If you want the bits in UK send me a PM or e mail and I will arrange it.

Wayne
Mar 20, 2015, 10:01 PM
Registered User
Wintr's Avatar
Quote:
Originally Posted by Wayne Giles
On second thoughts perhaps not - a meter I sent to the USA was attacked by US customs who drilled a hole through the display, presumably in case some white powder ran out - no comeback of cause; senders risk . Too much trouble to undo two screws and open the meter to look


Wayne
Sure hope that hasn't happened to mine.
Now I have reason to worry!
Mar 21, 2015, 01:58 PM
Registered User
Quote:
Originally Posted by Wintr
Sure hope that hasn't happened to mine.
Now I have reason to worry!
Richard,

Don't panic yet! I checked the postal receipt and it was despatched on March 6th so it should be with you in the next few days. Let me know if not.

Wayne
Mar 21, 2015, 11:59 PM
Registered User
Wintr's Avatar
Yeah, just a little comic relief. I haven't given up yet, given how our customs can be.
Mar 22, 2015, 08:12 AM
Registered User
I've purchased several items from Wayne over the years and never had an issue with any of the items I received. They've always been packaged well and wrapped in lots of bubble wrap.
Mar 22, 2015, 10:16 PM
Registered User
PM sent.
Bob
Mar 23, 2015, 02:29 PM
Registered User
propwash17's Avatar
PM'd for upgrade with label. Thank you.
Mar 23, 2015, 02:49 PM
Registered User
Quote:
Originally Posted by DanBo3D
Got my upgrade today, installation was smooth and easy.
In fact I did it without any desoldering, carefully pulled the circuit board away from the screen pins and I had plenty of room to remove and install the new chip.
Works perfect and the new features are a treat.
Thanks for making a great product even greater!!!
There is an increased risk of inserting the PIC incorrectly of you do not remove the PCB and it does put stress on the switch to lift the board without unsoldering it although it must be up to the individual.
Another possible way of unsoldering the switch without a solder sucker is to use a soldering iron with a larger bit so that you can melt both switch connections together and lift the pcb whilst they are both molten.
If you then remove the pcb, you can remelt the solder around the holes and wipe away the surplus with a damp cloth.

Wayne
Apr 09, 2015, 03:12 PM
Registered User
propwash17's Avatar
Hi, Wayne
Received my update chip and installed it today. I used the solder wick method to remove the solder as you suggested. Worked very well, took about ten minutes. Thanks for the improvement. Cheers, Ron
Apr 21, 2015, 10:37 PM
Registered User

ESR Meter Video review.


Just got my new ESR meter. Thanks Wayne. Made a little video review of the product if anybody is interested.

ESR Meter Review and Test on MaxAmps 100c Lipo (8 min 56 sec)
Apr 21, 2015, 11:33 PM
Registered User
Are_See_4_Me's Avatar
Quote:
Originally Posted by justadude
Just got my new ESR meter. Thanks Wayne. Made a little video review of the product if anybody is interested.

https://www.youtube.com/watch?v=peC5SbkrsqI
Nice review of the ESR meter. Based on the cell(s) IR shown for the Carbon 3S pack I would seriously consider replacing it sooner than later. All three cells were indvidually >11mΩ, which is a pretty high IR.

I computed the FOM (Figure Of Merit) for that pack at ~.62.

I'll bet that pack generates some heat when in use?
Apr 22, 2015, 10:45 AM
Registered User
Quote:
Originally Posted by Are_See_4_Me
Nice review of the ESR meter. Based on the cell(s) IR shown for the Carbon 3S pack I would seriously consider replacing it sooner than later. All three cells were indvidually >11mΩ, which is a pretty high IR.

I computed the FOM (Figure Of Merit) for that pack at ~.62.

I'll bet that pack generates some heat when in use?
Well surprisingly it doesn't heat up. After a flight it will be slightly warm but not hot. BTW when I measure the IR using my Powerlab6 it shows it to be 7.5m ohm. Not sure if there is a possibility that my ESR meter isn't calibrated properly?
Apr 22, 2015, 11:21 AM
Registered User
Are_See_4_Me's Avatar
Quote:
Originally Posted by justadude
Well surprisingly it doesn't heat up. After a flight it will be slightly warm but not hot. BTW when I measure the IR using my Powerlab6 it shows it to be 7.5m ohm. Not sure if there is a possibility that my ESR meter isn't calibrated properly?
I'm not sure where the disconnect is between the IR readings of your charger and your ESR meter.

I would err on the side of the ESR meter as it is specifically designed for IR measurements. I'm pretty sure that Wayne calibrates each meter individually before shipment. He (Wayne) might chime in on this.
Apr 22, 2015, 01:53 PM
Registered User
Quote:
Originally Posted by Are_See_4_Me
I'm not sure where the disconnect is between the IR readings of your charger and your ESR meter.

I would err on the side of the ESR meter as it is specifically designed for IR measurements. I'm pretty sure that Wayne calibrates each meter individually before shipment. He (Wayne) might chime in on this.
OK then!

I calibrate each meter as part of the testing setup using a nominal 10 milliohm resistor which I have measured accurately using calibrated instruments and has an actual value of 10.08 milliohms. There is inevitably a tolerance of +\- one bit on any digital setup which is +/- 0.04 milliohms.

The meter uses 16A current to measure the IR which is at least approaching the sort of currents we take in practice whereas chargers use different techniques and much lower current levels.
Inevitably therefore we arrive at slightly different IR figures but John Julian carried out a lot of comparative testing of the meter and several chargers.

Many chargers are way out but the i-chargers and the FMA powerlab chargers gave similar results with the i-chargers reading closest to the meter but slightly higher and the Powerlab chargers reading lower than the meter.

Jj. - glad to see your meter finally arrived and thanks for the video.
I will comment in the results in a separate post as I have just lost all the above and had to re-write it.

Wayne
Apr 22, 2015, 03:24 PM
Registered User
Quote:
Originally Posted by Wayne Giles
OK then!

I calibrate each meter as part of the testing setup using a nominal 10 milliohm resistor which I have measured accurately using calibrated instruments and has an actual value of 10.08 milliohms. There is inevitably a tolerance of +\- one bit on any digital setup which is +/- 0.04 milliohms.

The meter uses 16A current to measure the IR which is at least approaching the sort of currents we take in practice whereas chargers use different techniques and much lower current levels.
Inevitably therefore we arrive at slightly different IR figures but John Julian carried out a lot of comparative testing of the meter and several chargers.

Many chargers are way out but the i-chargers and the FMA powerlab chargers gave similar results with the i-chargers reading closest to the meter but slightly higher and the Powerlab chargers reading lower than the meter.

Jj. - glad to see your meter finally arrived and thanks for the video.
I will comment in the results in a separate post as I have just lost all the above and had to re-write it.

Wayne
Thanks Wayne, yeah I was very happy it finally showed up. My power labs charger is the newest version and I am wondering myself why there is such a big discrepancy between it and the ESR meter. My first inclination is that since the power labs charger measures the IR while charging and only gives the reading after putting 20-20%back in the pack maybe that has something to do with it. I did pull the pack directly off the charger and compared it with the ESR meter so there couldn't have been a temperature change in the comparison.

as far as the 16amp load that the ESR meter place while testing I am assuming that this is just a momentary load as the button is pressed? Not a constant load as long as the battery is connected to the meter?
Apr 22, 2015, 03:58 PM
Registered User
[QUOTE=justadude;31419033]Well surprisingly it doesn't heat up. After a flight it will be slightly warm but not hot. BTW when I measure the IR using my Powerlab6 it shows it to be 7.5m ohm. Not sure if there is a possibility that my ESR meter isn't calibrated properly?[/

For the "Lipotool" to give accurate results the lipo must be measured at between 22 and 25*C. I assume the readings were taken in that temperature range aand the results are not that bad.

As you will have seen in the instruction leaflet, the quoted maximum current is that which can be taken continuously from the pack and you can increase that figure by 40% for short term bursts. So it is saying that the 1850 pack is ok for 37A continuous and 52 A surge which is Ok for a pack of that size.

If the 1500mAh pack is not getting warm then you are not taking very high currents from it.

The heat generated within the lipo on load is a simple calculation and the "Lipotool" calculates the maximum safe current based on limiting this heat to a reasonable limit.

The calculation is:-

Heat dissipated in Watts = load current squared x IR

The obvious point to note is that the heat dissipated varies as the squareof the current so that if you double the current, the heat dissipated quadruples.

If we apply the calculation to the "100C" pack, then the initial heat dissipated within the pack at 100C, which the "Lipotool" would limit to 33watts, would be 827watts which is patently ridiculous; electric fire regions.
The IR drops as the pack heats up but it would still be several hundred watts which is obviously not sustainable.

Wayne
Apr 22, 2015, 04:04 PM
Registered User
Quote:
Originally Posted by justadude

as far as the 16amp load that the ESR meter place while testing I am assuming that this is just a momentary load as the button is pressed? Not a constant load as long as the battery is connected to the meter?

J,
That's right. The load pulse only lasts 15mS during which time the power device has to cope with just over 400W which it would not survive for any extended period. The meter only takes 20mA from the lipo apart from the load pulse.

Wayne
Apr 22, 2015, 05:06 PM
Registered User
[QUOTE=Wayne Giles;31421775]
Quote:
Originally Posted by justadude
Well surprisingly it doesn't heat up. After a flight it will be slightly warm but not hot. BTW when I measure the IR using my Powerlab6 it shows it to be 7.5m ohm. Not sure if there is a possibility that my ESR meter isn't calibrated properly?[/

For the "Lipotool" to give accurate results the lipo must be measured at between 22 and 25*C. I assume the readings were taken in that temperature range aand the results are not that bad.

As you will have seen in the instruction leaflet, the quoted maximum current is that which can be taken continuously from the pack and you can increase that figure by 40% for short term bursts. So it is saying that the 1850 pack is ok for 37A continuous and 52 A surge which is Ok for a pack of that size.

If the 1500mAh pack is not getting warm then you are not taking very high currents from it.

The heat generated within the lipo on load is a simple calculation and the "Lipotool" calculates the maximum safe current based on limiting this heat to a reasonable limit.

The calculation is:-

Heat dissipated in Watts = load current squared x IR

The obvious point to note is that the heat dissipated varies as the squareof the current so that if you double the current, the heat dissipated quadruples.

If we apply the calculation to the "100C" pack, then the initial heat dissipated within the pack at 100C, which the "Lipotool" would limit to 33watts, would be 827watts which is patently ridiculous; electric fire regions.
The IR drops as the pack heats up but it would still be several hundred watts which is obviously not sustainable.

Wayne
Yeah my mini quad only pulls 10-15amps and peaks out at 20amps. So it isn't pulling too much. When I took the measurements for the videos it was 21 degrees C.
Apr 22, 2015, 10:05 PM
Registered User
Hi,
I need an ESR to read small lipos, typically a Thunder Power 2S, 325 mah or equivalent. I noted that this device is limited to 500 mah minimum based on the packs's ability to tolerate 16 amps pulses. I believe a TP 325 mah 70C pack can easily take that kind of pulsed current. Will the ESR device actually allow testing of this type of battery?
Apr 23, 2015, 01:12 PM
Registered User
Bill Glover's Avatar
Quote:
Originally Posted by rivers
Hi,
I need an ESR to read small lipos, typically a Thunder Power 2S, 325 mah or equivalent. I noted that this device is limited to 500 mah minimum based on the packs's ability to tolerate 16 amps pulses. I believe a TP 325 mah 70C pack can easily take that kind of pulsed current. Will the ESR device actually allow testing of this type of battery?
There are simple mods to allow IR measurement for smaller cells (using a lower current for the pulse), and single-cell (1S) batteries. I've done both mods to mine.

https://www.rcgroups.com/forums/show...&postcount=364
Apr 23, 2015, 01:45 PM
Registered User
Quote:
Originally Posted by rivers
Hi,
I need an ESR to read small lipos, typically a Thunder Power 2S, 325 mah or equivalent. I noted that this device is limited to 500 mah minimum based on the packs's ability to tolerate 16 amps pulses. I believe a TP 325 mah 70C pack can easily take that kind of pulsed current. Will the ESR device actually allow testing of this type of battery?
Sorry for delay. There is the option Bill suggested although a decent 325mAh cell will cope with the 16A pulse and will give better resolution.

The problem with small 2S packs is that the pack voltage can drop below 7V during the pulse and this will give a false reading.
There are two ways round this. You can either buy the 1S - 6S version which is identical but has the facility to power the meter from a separate pack ( $5 extra for this 1S version) or youcan use the standard meter and connect another 2S or 3S pack in series with the pack you want to measure. It does not need to be the same capacity as the pack under test. You can then just measure the cells on the pack you are interested in. Just make sure that the total cell count of the two packs never exceeds 6S.

Wayne
Apr 23, 2015, 02:11 PM
Registered User
Mr Giles,

Please send me your PayPal address in order that I may purchase one of your
update packs for the original ESR meter.

Thanks,
Hugh Shoemaker
hshoe007@cox.net
Apr 24, 2015, 08:49 AM
Registered User
Bill Glover's Avatar
Quote:
Originally Posted by Wayne Giles
The problem with small 2S packs is that the pack voltage can drop below 7V during the pulse and this will give a false reading.
There are two ways round this. You can either buy the 1S - 6S version which is identical but has the facility to power the meter from a separate pack ( $5 extra for this 1S version) or youcan use the standard meter and connect another 2S or 3S pack in series with the pack you want to measure. It does not need to be the same capacity as the pack under test. You can then just measure the cells on the pack you are interested in. Just make sure that the total cell count of the two packs never exceeds 6S.
That's interesting, thanks Wayne. I have a lot of 350 & 380 2S packs ... all with 2mm bullets, so very easy to connect in series
Apr 24, 2015, 01:32 PM
Registered User
Quote:
Originally Posted by Bill Glover
That's interesting, thanks Wayne. I have a lot of 350 & 380 2S packs ... all with 2mm bullets, so very easy to connect in series
As long as you don't breach the 6S total limit and the voltage does not fall below 7V during the pulse, then the meter does not care what is in series in the chain.
The balance connectors just gives us a perfect way of measuring the IR of any cell in the chain with the 4 wire kelvin method.

The cell must have a minimum voltage of 3.2V in the latest version of the meter to prevent triggering the LV warning. With the original manually switched version you could even measure a Nicad of Nimh cell but the auto version needs a cell voltage of > 1.5V to change into Cell mode.

Wayne
Last edited by Wayne Giles; Apr 25, 2015 at 08:25 AM. Reason: Information on Nicad/ Nimh not correct
Apr 24, 2015, 07:20 PM
Registered User
Hi Wayne,

Questions regarding small lipos:
Where do I find the spec page and manual for the 1S to 6S version of the meter?
Since small cells could have high IR is there an upper limit for valid readings?

rivers

p.s. That's a clever trick about connecting packs in series.
Apr 25, 2015, 05:13 AM
Registered User
Bill Glover's Avatar
Quote:
Originally Posted by rivers
Since small cells could have high IR is there an upper limit for valid readings?
I know with the 2-6 cell meter the limit (individual cell) is 35 milliohms. When I tested my small Eflite/Parkzone cells after adding the low current mod. a couple of them gave "ESR out of range" ... which meant > 350 milliohms

Those went in the bin
Apr 26, 2015, 05:15 AM
Registered User
Quote:
Originally Posted by rivers
Hi Wayne,

Questions regarding small lipos:
Where do I find the spec page and manual for the 1S to 6S version of the meter?
Since small cells could have high IR is there an upper limit for valid readings?

rivers

p.s. That's a clever trick about connecting packs in series.
Apologies for delayed reply.

Bill is correct about the 35m.ohm range limit for cell measurement which will increase to 350m.ohms if you carry out the low current modification for very small cells ie < 200mAh. The mod. reduces the current pulse to 1.6A but of course the resolution is also 10x less.
If you want to measure large single cells you just need to order the 1S - 6S version which is identical to the standard unit except that it has an extra input socket to facilitate driving it from an external source. The specification is then exactly the same as the standard meter and is shown on the first post of this thread.

Here is a link to the single cell and low current mod. details

https://www.rcgroups.com/forums/show...&postcount=364

The trick of putting another pack in series is obvious but it has taken me 4 years to think it up!!

Wayne
May 02, 2015, 04:10 AM
Registered User
First of all, thanks Wayne for the great ESR meter and I had bought the chip from him for the update of my ESR meter. And had since few cases where the IR readings of some of my batteries were way out and was caught by this meter.

However I had a nanotech 6S 5000mah battery which had been bloated from usage after 20-30 flights and when I measured the IR of each cell in this battery, it was reading approx. 2.48mohms to 2.58 mohms each cell with the C rating shown on the meter approx. 21 to 22C each...

But when I installed this battery into my EDF jet does not have enough power to take off and hence aborted the take-off. A new lipo was fitted in and the jet took off without any issue, hence ruling out any electronics or motor problem.

Hence, the question is : does it meant that if the IR readings of a battery are good, the battery will be good?

Can anyone advise. tks!
Last edited by viperviper; May 02, 2015 at 04:16 AM.
May 02, 2015, 12:14 PM
Registered User
Quote:
Originally Posted by viperviper
First of all, thanks Wayne for the great ESR meter and I had bought the chip from him for the update of my ESR meter. And had since few cases where the IR readings of some of my batteries were way out and was caught by this meter.

However I had a nanotech 6S 5000mah battery which had been bloated from usage after 20-30 flights and when I measured the IR of each cell in this battery, it was reading approx. 2.48mohms to 2.58 mohms each cell with the C rating shown on the meter approx. 21 to 22C each...

But when I installed this battery into my EDF jet does not have enough power to take off and hence aborted the take-off. A new lipo was fitted in and the jet took off without any issue, hence ruling out any electronics or motor problem.

Hence, the question is : does it meant that if the IR readings of a battery are good, the battery will be good?

Can anyone advise. tks!
I noticed the same anomaly when testing my 4s 4200 packs. One of my puffed packs that only flies for 6 minutes tested at a lower IR then the same pack in good condition that I fly for 10 minutes. Not sure why that would be possible? Maybe Wayne could chime in on that.
May 02, 2015, 04:46 PM
RC Keeps Me Sane
DanBo3D's Avatar
Apparently IR isn't relative so to speak as I also had a few batteries that would just fall flat in flight. When checked, IR was no indication of what cell was failing. Needless to say I just scrapped the battery.
Nothing was puffed either.
May 02, 2015, 05:08 PM
Registered User
Although the IR of a cell tells you how the cell will normally perform, it cannot tell you if the cell has some other problem in it. I do not know how many or what failure modes a cell has, but they would not necessarily all affect the readable IR.

As an example I have a GensAce 55C pack which I was running through a series of full discharge tests under constant current load at increasing steps of 5C and was part way through the 35C run when the voltage suddenly partially collapsed.
One cell had cried enough, but when the pack had cooled it appeared to have recovered showing just a small increase in IR on that one cell.
A repeated load test resulted in a repeat peformance, so that I now have a pack which appears OK reading IR but obviously it has a damaged cell which will only deliver load current for a short period (until the temperature has risen possibly??)

The 6S nanotech could well have the same problem; if one cell collapses after a few seconds of heavy load it could well explain the lack of take off power.

Wayne
May 02, 2015, 05:21 PM
ancora imparo
jj604's Avatar
In addition to Wayne's comments you might be interested in the case where a pack gives an incorrect low reading but it is uniformly so for all cells. The meter is designed to measure the IR of cells in good condition. If the whole pack is far gone then you may get a misleading low value of IR.

I found this when I first started testing IR vs. actual performance. I had a very old Hyperion of the same size and cell count as a new Hayin pack and both were reporting similar IR values but the Hyperion was dramatically inferior in practice and could barely sustain a 7C discharge rate.

The reason is that poor cells do not allow the voltage drop which the meter measures to establish within the time of the load pulse. The meter measures the drop in voltage from unloaded to loaded when a 16 Amp current is pulled from the cell.

The two graphs show this.

When the Hayin is loaded by the meter the voltage drops very quickly and levels out and has been stable for some time when the meter takes the voltage reading to establish the IR.

For the Hyperion, the voltage is still falling when the reading is taken and it also recovers much more slowly. The voltage is too high and has not stabilised when the reading is taken so that the voltage drop is read as too low and gives an incorrect low value of IR. To get an accurate IR value the load pulse would have to be much longer and the meter components, namely the power FET, would be overloaded and burn out.

It would be possible I suppose to program a microprocessor to measure the rate of change of voltage and issue a warning if this was happening but I'm pretty sure Wayne won't be doing it. This meter is a classic example of excellent analog measurement. Most of the time it does what it is meant to very well indeed. You do have to be aware that it has some measurement limits though.

John
Last edited by jj604; May 02, 2015 at 05:43 PM.
May 02, 2015, 11:58 PM
Registered User
very informative! thanks to Wayne and John
May 03, 2015, 08:34 AM
Registered User
Quote:
Originally Posted by jj604
In addition to Wayne's comments you might be interested in the case where a pack gives an incorrect low reading but it is uniformly so for all cells. The meter is designed to measure the IR of cells in good condition. If the whole pack is far gone then you may get a misleading low value of IR.

I found this when I first started testing IR vs. actual performance. I had a very old Hyperion of the same size and cell count as a new Hayin pack and both were reporting similar IR values but the Hyperion was dramatically inferior in practice and could barely sustain a 7C discharge rate.

The reason is that poor cells do not allow the voltage drop which the meter measures to establish within the time of the load pulse. The meter measures the drop in voltage from unloaded to loaded when a 16 Amp current is pulled from the cell.

The two graphs show this.

When the Hayin is loaded by the meter the voltage drops very quickly and levels out and has been stable for some time when the meter takes the voltage reading to establish the IR.

For the Hyperion, the voltage is still falling when the reading is taken and it also recovers much more slowly. The voltage is too high and has not stabilised when the reading is taken so that the voltage drop is read as too low and gives an incorrect low value of IR. To get an accurate IR value the load pulse would have to be much longer and the meter components, namely the power FET, would be overloaded and burn out.

It would be possible I suppose to program a microprocessor to measure the rate of change of voltage and issue a warning if this was happening but I'm pretty sure Wayne won't be doing it. This meter is a classic example of excellent analog measurement. Most of the time it does what it is meant to very well indeed. You do have to be aware that it has some measurement limits though.

John
John/Wayne, Do you think it would be helpful to know the lowest voltage during the sample period would you need to know the entire dv/dt during the sample period?
May 03, 2015, 01:14 PM
Registered User
Quote:
Originally Posted by Ohmic
John/Wayne, Do you think it would be helpful to know the lowest voltage during the sample period would you need to know the entire dv/dt during the sample period?
Ohmic,

Not quite sure what you are asking. Can you be more explicit.

Certainly I have seen exactly the same plot that John has shown from a very poor or old lipo. They respond as though there is a huge capacitor in parallel with them ie they take a long time for the voltage to settle after a step change in current, whether it be an increase or decrease.
Generally a new lipo settles in well under 10mS so that the 15mS pulse load from the meter leaves ample time for it to settle.

The voltage might take 100s of mS to settle which is impractical. The error is not as large as it first appears as the recovery is always asymptotic, but it does give an optimistic result from a poor cell.

Wayne
May 03, 2015, 06:51 PM
Registered User
Wintr's Avatar
Perhaps he means you could measure the voltage at two or three times during the 15mS, and estimate the dV/dT from that. If that value is too high (to be defined), then flag a failing cell. Seems like a lot of work, but, if your processor is fast enough ...
May 03, 2015, 08:58 PM
Registered User
Quote:
Originally Posted by Wayne Giles
Ohmic,

Not quite sure what you are asking. Can you be more explicit.

Certainly I have seen exactly the same plot that John has shown from a very poor or old lipo. They respond as though there is a huge capacitor in parallel with them ie they take a long time for the voltage to settle after a step change in current, whether it be an increase or decrease.
Generally a new lipo settles in well under 10mS so that the 15mS pulse load from the meter leaves ample time for it to settle.

The voltage might take 100s of mS to settle which is impractical. The error is not as large as it first appears as the recovery is always asymptotic, but it does give an optimistic result from a poor cell.

Wayne
Hi Wayne, I was wondering if it would be helpful to measure the voltage at several intervals during the 15ms window and keep the lowest recorded voltage or perhaps use the average voltage? Was wondering if there's a way to identify this condition?
May 11, 2015, 10:18 AM
Registered User
interested in your ESR meter
thx
Rich
May 11, 2015, 02:08 PM
Registered User
Quote:
Originally Posted by Ohmic
Hi Wayne, I was wondering if it would be helpful to measure the voltage at several intervals during the 15ms window and keep the lowest recorded voltage or perhaps use the average voltage? Was wondering if there's a way to identify this condition?
Pete,

Apolgies for delay in replying; I have only just seen your post.

It probably could be done as you suggest although I am not a software man. The problem now is that the PIC is absolutely full. There are no free bytes in the memory so that any addition would require a different PIC and a complete redesign.
We did try multiple pulsing in the design phase but it did not show any advantage.
Actually it is probably only necessary to measure the voltage twice as dv/dt should be zero after about 10mS for a normal lipo, but I think all we could do is to flag up a warning.
I have tried adding step changes to a constant current load during a full power discharge of a lipo pack and the voltage step consistently correlates with the IR results derived from the meter.

Wayne
May 11, 2015, 02:15 PM
Registered User
Quote:
Originally Posted by lowdensity
interested in your ESR meter
thx
Rich
Prices and details are on the first post in t his thread.

If you want to purchase one you can buy direct from me by sending me a PM and I will then give you my e mail address to which you can send funds via PayPal.
I don' t know where you are but postage for various areas are also on the first post.
If you are in the USA, the units are also sold by ProgressiveRC in Seattle.

Wayne
May 18, 2015, 12:55 PM
mostly gliders
liukku's Avatar
Just got my update kit from Wayne and will fix the update tonight. However, I have a question concerning the minimum voltage at discharge test and when formatting of new LiPo batteries? I know I read the info somewhere but can not find it. Have a vague memory not go lower than 3.7V?

Thanks in advance!

/Ville
May 18, 2015, 01:24 PM
Registered User
Quote:
Originally Posted by liukku
Just got my update kit from Wayne and will fix the update tonight. However, I have a question concerning the minimum voltage at discharge test and when formatting of new LiPo batteries? I know I read the info somewhere but can not find it. Have a vague memory not go lower than 3.7V?

Thanks in advance!

/Ville
Viljo,

The 3.7V is very conservative. If you discharge a lipo cell under high load down to 3V at turn off it will rebound to about 3.3/3.4V. I did a lot of power discharge testing some years back and used 3.0V as a loaded cut off voltage. This generally meant that the cell delivered very near to its rated capacity in mAh. I never had any lipo show signs of damage although I always recharged the pack immediately.

I do think that this problem is overstated . If you never discharge below about 3.2V on load, you will definitely not have a problem.

W ayne
May 18, 2015, 02:13 PM
mostly gliders
liukku's Avatar
Quote:
Originally Posted by Wayne Giles
Viljo,

The 3.7V is very conservative. If you discharge a lipo cell under high load down to 3V at turn off it will rebound to about 3.3/3.4V. I did a lot of power discharge testing some years back and used 3.0V as a loaded cut off voltage. This generally meant that the cell delivered very near to its rated capacity in mAh. I never had any lipo show signs of damage although I always recharged the pack immediately.

I do think that this problem is overstated . If you never discharge below about 3.2V on load, you will definitely not have a problem.

W ayne
Hello Wayne!
I thank you for your extremely fine support, both here and in private. Can announce that I just made the update, and it went like clockwork. :-)
Must be sure to keep me updated on this topic as well so you do not miss good news.

/Ville
May 18, 2015, 02:33 PM
Registered User
Bill Glover's Avatar
Quote:
Originally Posted by Wayne Giles
I do think that this problem is overstated . If you never discharge below about 3.2V on load, you will definitely not have a problem.
It depends a bit on the application. My multirotors use 8000 mAh packs and can pull as little as 21A in flight. That's only a 2.6C discharge rate, so there's no way I'd take them down to 3.2V per cell.

However I happily hammer the 360-480 mAh packs on my indoor 3D foamies by flying them right down to LVC on just about every flight (peak current around 9A, so over 20C discharge). Some of those are over 6 years old now!
Jun 04, 2015, 02:01 AM
Registered User
Good day,
I am just about ready to order Wayne's ESR meter and can't decide between the 1S-6s meter or 2S-6S meter and would need clarification on the following point:.
Apart from the capability of the 1s-6s meter to do a measurement on 1 cell battery, is there any other difference from the 2s-6s meter. Currently, I have packs ranging from 460mAh to 2200mAh but I would like to be ready for lower capacity packs for indoor models in the future.
Will appreciate your inputs.
Best regards
Jun 04, 2015, 02:44 AM
Registered User
Quote:
Originally Posted by funflynut
Good day,
I am just about ready to order Wayne's ESR meter and can't decide between the 1S-6s meter or 2S-6S meter and would need clarification on the following point:.
Apart from the capability of the 1s-6s meter to do a measurement on 1 cell battery, is there any other difference from the 2s-6s meter. Currently, I have packs ranging from 460mAh to 2200mAh but I would like to be ready for lower capacity packs for indoor models in the future.
Will appreciate your inputs.
Best regards
Funfly,

The 1s-6S meter is exactly the same as the 2S-6S meter but has the additional facility of a flying lead with a JST connector on it to enable the user to power the electronics of the meter from an external source such as a small lipo or a PP9 battery. This is necessary when measuring single cell lipo packs as the meter needs minimum of about 7V which is normally supplied by the lipo under test.

If you are measuring very small 2S packs which could have weak cell it is good practice to use this facility as such a pack might also fall below 7V during the measurement pulse.

Although the specification is 500mAh - 10,000mAh, the meter will measure packs down to about 300mAh subject to the limitations specified above.

The extra cost for the 1S facility is $5.

Wayne
Last edited by Wayne Giles; Jun 04, 2015 at 03:21 AM. Reason: Typo
Jun 14, 2015, 07:32 PM
Registered User
Thanks for the clarification Wayne. I have placed the order for 1S-6S ESR meter. Looking forward to receiving it.
Cheers
Aug 20, 2015, 06:05 PM
Registered User

160 mah


Quote:
Originally Posted by Wayne Giles
Funfly,

The 1s-6S meter is exactly the same as the 2S-6S meter but has the additional facility of a flying lead with a JST connector on it to enable the user to power the electronics of the meter from an external source such as a small lipo or a PP9 battery. This is necessary when measuring single cell lipo packs as the meter needs minimum of about 7V which is normally supplied by the lipo under test.

If you are measuring very small 2S packs which could have weak cell it is good practice to use this facility as such a pack might also fall below 7V during the measurement pulse.

Although the specification is 500mAh - 10,000mAh, the meter will measure packs down to about 300mAh subject to the limitations specified above.

The extra cost for the 1S facility is $5.

Wayne
what about the 160 mah that are used with the umx planes from horizon?
thanks
Aug 21, 2015, 02:13 AM
Registered User
Quote:
Originally Posted by phil alvirez
what about the 160 mah that are used with the umx planes from horizon?
thanks
Phil,

The measuring pulse is too large for a lipo cell as small as 160mAh on the standard meter but you can add a modification to enable the meter to measure very small cells. Details are at: https://www.rcgroups.com/forums/show...&postcount=364.
You would also need to make up a small adapter lead to mate with the tiny connector which these cells use.

Th problem with these connectors is that, being tin plated, their contact resistance is high and very variable so that the results are of limited value.

Wayne
Aug 22, 2015, 04:47 AM
Registered User
thank you, Wayne.
regards
Nov 30, 2015, 10:37 AM
Registered User
Ken Myers's Avatar

Some observations and questions for Wayne


Wayne, I have a couple of questions regarding some readings I’ve taken with the LiPo ESR Meter, Full Analysis Version, 2 - 6 Cells MAXIMUM.

I absolutely understand that temperature has a HUGE effect on the IR readings, but...

Dinogy 3S 800mAh 65C at 22ºC
Pack Voltage: 11.48
Pack ESR in milliohms: 55.2

Cell 1 (most negative)
volts: 3.83
state of charge: 41% charged
cell IR in milliohms: 16.80
Max. continuous Amp draw: 15.2
Real C rate: ~19

Cell 2 (middle cell)
volts: 3.83
state of charge: 39% charged
cell IR in milliohms: 17.75
Max. continuous Amp draw: 14.4
Real C rate: ~18

Cell 3 (most positive cell)
volts: 3.83
state of charge: 39% charged
cell IR in milliohms: 17.24
Max. continuous Amp draw: 15.2
Real C rate: ~19

The three cells’ IR added together: 51.8 milliohms
Pack ESR 55.2 mOhm - 51.8 mOhm = 3.4 milliohms
Is that difference, 3.4 milliohms, the IR for the power leads, connectors, meter, etc.?

Same pack at cooler temperature (my basement temperature)
Dinogy 3S 800mAh 65C at 16.8ºC
Pack Voltage: 11.48
Pack ESR in milliohms: 70.2 (as expected)

Cell 1 (most negative)
volts: 3.83
state of charge: 49% charged (went up 8%)
cell IR in milliohms: 22.00
Max. continuous Amp draw: 13.6
Real C rate: ~17

Cell 2 (middle cell)
volts: 3.83
state of charge: 49% charged (went up 10%)
cell IR in milliohms: 23.12
Max. continuous Amp draw: 12.8
Real C rate: ~16

Cell 3 (most positive cell)
volts: 3.83
state of charge: 49% charged (went up 10%)
cell IR in milliohms: 22.36
Max. continuous Amp draw: 13.6
Real C rate: ~17

The three cells’ IR added together: 67.48 milliohms
Pack ESR 70.2 mOhm - 67.48 mOhm = 2.72 milliohms
I believe the lower milliohms difference at the lower temperature is because the wires and connectors and meter are cooler, yes?

Why is there a difference presented on the ESR meter screen of the charge state of almost 10% when the pack is cooler?

A different pack and more questions:

Admiral 3S 1100mAh 25C at 22ºC
Pack Voltage: 12.48
Pack ESR in milliohms: 68.4

Cell 1 (most negative)
volts: 4.17
state of charge: didn’t note, as hadn’t realized it changed with temperature
cell IR in milliohms: 21.28
Max. continuous Amp draw: 17
Real C rate: ~15

Cell 2 (middle cell)
volts: 4.18
state of charge: didn’t note
cell IR in milliohms: 23.24
Max. continuous Amp draw: 16
Real C rate: ~14

Cell 3 (most positive cell)
volts: 4.17
state of charge: didn’t note
cell IR in milliohms: 23.44
Max. continuous Amp draw: 16
Real C rate: ~14

The three cells’ IR added together: 67.96 milliohms
Pack ESR 68.4 mOhm - 67.96 mOhm = 0.44 milliohms
Why such a big difference between the Dinogy @ 22ºC (3.4 milliohms) and this one @ 22ºC (0.44 milliohms)?

Same pack at cooler temperature
Admiral 3S 1100mAh 25C at 16.5ºC

Pack Voltage: 12.48
Pack ESR in milliohms: 91.8 (as expected)

Cell 1 (most negative)
volts: 4.17
state of charge: 97% charged
cell IR in milliohms: 29.24
Max. continuous Amp draw: 14
Real C rate: ~12

Cell 2 (middle cell)
volts: 4.18
state of charge: 98% charged
cell IR in milliohms: 31.40
Max. continuous Amp draw: 14
Real C rate: ~12

Cell 3 (most positive cell)
volts: 4.17
state of charge: 97% charged
cell IR in milliohms: 31.00
Max. continuous Amp draw: 14
Real C rate: ~12

The three cells’ IR added together: 91.64 milliohms
Pack ESR 91.8 mOhm - 91.64 mOhm = 0.16 milliohms
Again there is a big difference between the Dinogy @ 16.8ºC (2.72 milliohms) and this one @ 16.5ºC (0.16 milliohms)

Could you please explain?

Thanks,
Ken
Nov 30, 2015, 04:05 PM
Registered User
Ken,

The reason for the apparent variation of the difference between the pack IR value and the sum total of the cells is a combination of factors of which temperature may be one, but the major reason is almost certainly that the figure you are looking for is the difference between two large values. This means that measurement errors are magnified .
Eg in the example you are quoting the pack value of 68m.ohms only needs to be 2% out (1.36m.ohm) to produce an error in the 2.4m.ohm difference of 56%..

The 68m.ohm figure is always subject to being + or - 1 bit which is 0.6 m.ohms and of course there is some error in the analogue measurement circuitry. Also be aware that most connectors, particularly Deans knock offs, vary from one insertion to the next. Try taking a measurement, reinserting the power connector and take another one . It will almost certainly be different depending on how clean the contacts are.

The meter is intending to give you a safe max continuous current that you can discharge a lipo at. It is conservative and a rule of thumb but has proved surprisingly accurate over a wide range of packs.

The recommended temperature of 22*C is intended to allow direct comparison of packs. It is based on the maximum allowable initial heat dissipation in the pack, so that as the IR rises with falling temperature, this max current also falls.
This is logical and correlates with the fact that lipos fail more often in winter conditions. A current you take safely in summer conditions subject the lipo to much more stress in the winter.

The one point you make that I cannot explain is the difference in the apparent display of different states of charge for the same cell voltage at different temperatures. The meter has a built in algorithm which has a fixed plot of cell voltage against % charge and temperature has no input into the equation.

Can you check by taking more readings and I will investigate to see which of the readings are actually correct.

Wayne
Dec 01, 2015, 08:16 AM
Registered User
Ken,

I have further looked into the apparent change of percentage charge state that you have quoted and I can only reiterate my comments above.

The algorithm in the processor is based an a non linear plot derived from several sources and refined by Mark Forsyth and John Julian.

It is a "look up table" in the processor which is defined by the cell voltage and therefore I cannot see how the processor can display different charge levels for the same voltage. The correct figure for 3,83V is 49% and the same ADC reading is used to produce both the voltage reading and the % charge reading so that it is difficult to see how the display can show two different results from the same source.
3.80V should read 41% and 3.79 V should read 39% which are respectively 6 and 8 steps away on the ADC readout.
I assume you were reading the voltage from the meter and not another measurement device such as a charger or DVM?
Can you try some other readings and post the results so that I can check that they correlate with the lookup table.

Wayne
Dec 01, 2015, 09:08 AM
Registered User
Ken Myers's Avatar
Thanks Wayne. I'm sorry I wasted your time, as I truly did.

I carefully checked three different packs this morning and all the SOC percentages came out 'as they should'. I believe that it was 'this old man' making the same mistake in reading and doing it THREE TIMES!

I still did find the Admiral 3S 1100mAh 25C to be the odd man out when it came to the difference between the packs ESR and each cells' milliohms added together.

One thing I did note this morning was that of the three packs that I very carefully tested this morning and repeated the test again, the Admiral had 14AWG wire on the power leads, while the other two packs had 16AWG wire on the power leads.

I don't use an infrared thermometer for the pack readings. I use the probe type taped firmly to the 'side' of the middle cell. All three packs sat in the basement for 3 hours or more. The blue colored covering on the Dinogy 3S 800mAh pack read the lowest (16.8ºC), the black colored Admiral 3S 1100mAh pack read the highest (17.5ºC) and the orangish red colored covering of a Dinogy 3S 1000mAh 30C (17.2ºC). I avoided handling the packs and also allowed the tape to be on the packs and thermometer to settle.
Last edited by Ken Myers; Dec 01, 2015 at 12:58 PM. Reason: Retracted color of covering statement


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