Espritmodel.com Telemetry Radio
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Old Dec 03, 2012, 04:05 PM
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Orlando, Fl
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Wayne,

Where can I buy one of these? I think I saw two different types: one would work with 2-6 cells and one would read 1s as well. I think the 1s capable version needed a separate battery? Can you explain the differences?

Jason
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Old Dec 03, 2012, 05:13 PM
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Rugby, UK
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Originally Posted by jhroof View Post
Wayne,

Where can I buy one of these? I think I saw two different types: one would work with 2-6 cells and one would read 1s as well. I think the 1s capable version needed a separate battery? Can you explain the differences?

Jason
Hi Jason,

You can get a meter from ProgressiveRC in Seattle, SMC Racing in Elkton or F3A Unlimited or you can buy one direct from me in the UK.
See: http://www.rcgroups.com/forums/showt...323465&page=17
(If you want the single cell capability modification it is $6 extra.)

Any price difference is compensated for by extra shipping costs from UK.

The difference between the standard 2S - 6S version and the 1S - 6S verion is just the addition of an auxilliary input enabling the electronics within the unit to be fed from a separate source as they neeed a minimum of 6V. This is normally supplied by the pack under test, but of couse, a single lipo cell cannot supply this.

BTW both David at ProgressiveRC and Danny at SMC Racing are making genuine efforts to inform customers of the real performance of the lipos they are selling which is refreshing change in this area of marketing fairy tales.
They should be congratulated as potentially they are hurting their own sales by telling the truth.
Information might also help Mike Anderson above

Wayne
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Old Dec 03, 2012, 06:15 PM
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Wayne, if I make the single cell modification, can I use the single cell approach (seperate power supply) to check the IR Value of cells in a 10S configuration that only has one power plug. Works fine on 5S configurations, but a lot of pattern guys fly 10S with only one power plug instead of 2 5S in series.

Thanks
Don
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Old Dec 03, 2012, 07:18 PM
ago involo ergo sum
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Kemptville, Ontario, Canada
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Originally Posted by Wayne Giles View Post
Mike, Are you measuring at 22degC and leaving the packs in that ambient temperature to settle for at least an hour ( preferably more) ?
Also how old are these packs?

Wayne
All are measured at a stabilised (several hours) 21C.
I tried to find purchase records for these packs but couldn't. I'm thinking the Turnigy was bought in spring 2011 and the TP in late summer 2011.
The Turnigy might have 5 cycles on it. The TP has only one cycle (on the charger, not flown yet) I've had a very poor flying season in 2012 due to workload.
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Old Dec 03, 2012, 08:36 PM
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The TP has only one cycle (on the charger, not flown yet) I've had a very poor flying season in 2012 due to workload.
The IR of the TP will likely drop some in the next 5-10 cycles then, most LiPos do.
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Old Dec 03, 2012, 10:25 PM
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Good point. It most certainly should drop somewhat, if the pack was indeed 'brand new' when purchased. The downside is that I have never seen measured IR from any lipoly improve by more than 20-25%, which still leaves the TP in the 'very mediocre' category, especially for a 45C premium brand.

Curiously, was the 4.92mOhm cell an aberration or was it consistent with the other cells?

Mark
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Old Dec 04, 2012, 10:03 AM
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I've had a few pp65 and v2pl packs and the IR of them have not been the best around if the numbers I read here are to be believed. The packs perform great and last forever. I had one pack for almost three years and 170 cycles and when I sold it it still performed as new and the IR was just a hair better than it was when new.
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Old Dec 04, 2012, 03:34 PM
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Quote:
Originally Posted by DonA View Post
Wayne, if I make the single cell modification, can I use the single cell approach (seperate power supply) to check the IR Value of cells in a 10S configuration that only has one power plug. Works fine on 5S configurations, but a lot of pattern guys fly 10S with only one power plug instead of 2 5S in series.

Thanks
Don
Don,

You don't need to do the 1S modification to read the individual cell values of a 10 cell pack. You just need to make up a little adapter to connect the power leads via the balance connector.
Someone else asked the question way back and I gave the details further back in the thread. You can find it at :-
http://www.rcgroups.com/forums/showp...&postcount=198

Having just read it through, I'm not convinced it is entirely clear.
If it is not let me know and I will try to post a sketch to clarify it.

Wayne
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Old Dec 04, 2012, 03:55 PM
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Wayne,
Can you post a sketch, please?
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Old Dec 05, 2012, 12:24 PM
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I have done a sketch showing how to use the meter on packs of more than 6 cells.

Sorry the sketch is crude - I have just got i-Draw but not learned how to use it yet!

As you MUST NOT apply more than 6 cells between the power leads, to measure cells 7 - 10 of a 10 cell pack you must connect the meter +ve power lead to the +ve Pack power lead and the meter -ve lead to the -ve end of cell 6 via the balance connector. You need to make up simple adapters to facilitate this.
The sketch shows this and the voltage sense lead can now be inserted into the balance connector as usual to measure cells 7, 8, 9, and 10.
To measure cells lower down you simply move the power leads further down the chain and you can always measure any cell between the power lead connections, always OBSERVING THE 6 CELL LIMIT between the power leads.

The extra resistance of the adapters and balance lead connectors will not affect the accuracy of the readings.

Do be careful not to accidentally apply more than 6 cells across the power leads - if you push the 'Read' button in that condition it WILL damage the unit.

Wayne


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Old Dec 05, 2012, 06:30 PM
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Melbourne, Australia
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Quick and easy

Just to reinforce why I love my WWM (Wayne's Wonderful Meter - with apologies to Isambard Kingdom Brunel).

1) I recently had to sort through a pile of little 1S 160mAh cells for my indoor stuff. I had about 30 that had been tortured in various ways when I was testing these little guys on the CBA. No idea what condition they were in.

Took less than 5 minutes to sort them into Good, OK and Chuck with the meter. It would have taken at least 3-4 hours with the CBA even if everything had worked perfectly which of course it never does. Longer if I had to flight test them all.

2) I just finished a small electric conversion of a DLG that uses a 2S battery pulling about 9 Amps. I had 4 supposedly identical Turnigy 2S 800mAH 20-30C packs, an old Kokam 800mAh 30C I had put in it originally and a 1000mAh I had made up from 2x 500mAh Turnigy 20-30C. Had assumed they would all be similar in performance with the advantage to the higher capacity 1000mAh.

Here's the results. CBA test shows how accurate a predictor the ESR meter is.

The Turnigy #4 is dramatically better than its 3 siblings and on a par for voltage at 9 Amps with the 1000mAh which is 30% heavier. The 4 Turnigy's are identically labelled and bought at almost the same time. #4 is slightly longer and a few g heavier and is obviously totally different cells despite the labelling.

As people say, the fun thing about HobbyKing is that it's just like a box of chocolates, you never know just what you are going to get.

John
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Old Dec 05, 2012, 06:39 PM
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Brilliant John!

A wonderful empirical example of how ESR (IR) measurements are an extremely accurate predictor for discharge performance. And, far easier to accomplish and no damage to packs.

IMO, this post would be excellent fodder for the Lipoly Performance Tool discussion thread. Might I suggest a link over there that points to this data?

Cheers,
Mark
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Old Dec 05, 2012, 06:41 PM
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Mark that sounds a good thread. I must look at it.
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Old Dec 06, 2012, 12:18 AM
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Belgium, Flemish Region, Oosterzele
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Originally Posted by jj604 View Post
The Turnigy #4 is dramatically better than its 3 siblings and

John
I had similar results with my 40C 800 Turnigy cells, one cell very good, one worse, 2 average. They all look the same and were bought at the same time:

Turnigy 41 800 40 6 5 to 10 17 26.5c Icharger 206B 0.88 17 21
Turnigy 42 800 40 6 5 to 10 12 26.5c Icharger 206B 1.25 20 25
Turnigy 51 800 40 6 5 to 10 20 26.5c Icharger 206B 0.75 15 19
Turnigy 52 800 40 6 5 to 10 17 26.5c Icharger 206B 0.88 17 21
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Old Dec 06, 2012, 10:47 AM
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Orlando, Fl.
Joined Sep 2006
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Question for Wayne

Having just purchased a Blade mCPx V2, I now have a need to check 1S lipos. My friends and I have ordered the 6 lead pigtail parallel charging lead. It occurred to me that I could cut the UM connectors with leads out of the pigtail and make up a harness to create a 2S, 3s, etc., battery by connecting them in series and (observing polarity), connect a Deans connector. I could then take a balance connector and insert it's leads in the appropriate places between each cell.

These cells will be 200 to 300 mAh each. Is my thinking correct that this would be the same, (using 200 mAh cells, for example), as a 3S, 600mAh battery?

I realize the UM connectors and the leads will add resistance not found in a assembled battery pack with soldered tabs, etc., but as a tool for comparison, would this work and not overload the individual cells with the pulse?
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