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Old Mar 06, 2011, 03:14 PM
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Rugby, UK
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Originally Posted by speed2004 View Post
I ran out of British Sterling...LOL
So have we! - nearly anyway.

If you look at the start of the post you will see that I take $ and Euros also.

I have also run out of meters and will have to make a new batch. I need to order PCBs in a reasonable quantity just to break even, so it is not possible to make a single unit. I already have three other people waiting and will certainly make another batch in the next few weeks.
If anyone else is in the market, please let me know; I don't mind taking some risk, but not much as there is no profit motive involved

Wayne.
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Old Mar 07, 2011, 05:13 AM
who dares wins
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London,England
Joined Apr 2005
1,853 Posts
Your device is a handy accurate cell volt measuring device also! My pocket cell volt device's accuracy (Fusion smart guard) is miserable in comparison.

Some more numbers.

These six packs are brand new, never charged, just unwrapped and connectors added. I got the Loong max two months ago; they’ve been dry stored at ~ 5 centigrade. I got the Thunder Powers last week. I fitted 4mm gold bullets to the two 4s packs and 6.5mm CC bullets to the four 5s packs.

All were measured at home yesterday, ambient temperature 20 C (68 Fahrenheit) after having been at 20 degrees centigrade for 6 hours

Loong Max Tipple 4500mAH 5s 30C
Pack 1 IR=26.1
Cell volts: 3.85, 3.85, 3.84, 3.84, 3.84
Cell IR: 3.04, 3.20, 3.16, 2.88, 4.28

Pack 2 IR=24.6
Cell volts: 3.85, 3.84, 3.84, 3.84, 3.84
Cell IR: 2.44, 2.40, 2.64, 2.56, 3.96

TP G6 3300mAH 4s 65C
Pack 1 IR=24
Cell volts: 3.82, 3.82, 3.82, 3.82
Cell IR: 3.96, 4.44, 3.92, 3.80

Pack 2 IR=24.9
Cell volts: 3.82, 3.82, 3.82, 3.82
Cell IR: 3.92, 4.28, 4.12, 4.08

TP G6 5000mAH 5s 65C
Pack 1 IR=24.6
Cell volts: 3.82, 3.82, 3.82, 3.82, 3.82
Cell IR: 2.74, 2.78, 2.86, 2.86, 2.78

Pack 2 IR=24.0
Cell volts: 3.83, 3.83, 3.82, 3.82, 3.82
Cell IR: 2.66, 2.82, 2.66, 2.74, 2.62

The proposed uses are:
4s pattern at ~40-45amps WOT on the ground, 3D aero at ~55-60amps WOT on the ground, EDF at ~50-60amps WOT on the ground (which wont decrease on the air).
5s pattern at ~80-90amps WOT on the ground

edit: i'll add pack weights later and update on the numbers once a decent number of cycles have been put on the packs.

Alex
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Old Mar 07, 2011, 10:25 AM
Ignint McNugget
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behind Jaggi lines
Joined Jan 2004
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Quote:
Originally Posted by Wayne Giles View Post
... If anyone else is in the market, please let me know; I don't mind taking some risk, but not much as there is no profit motive involved

Wayne.
Please put me on the waiting list Wayne.
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Old Mar 07, 2011, 02:30 PM
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Rugby, UK
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Originally Posted by Rumple View Post
Please put me on the waiting list Wayne.
OK Rumple - will do.

Wayne
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Old Mar 07, 2011, 02:56 PM
Registered User
Rugby, UK
Joined Feb 2007
896 Posts
Quote:
Originally Posted by like2fly! View Post
Your device is a handy accurate cell volt measuring device also! My pocket cell volt device's accuracy (Fusion smart guard) is miserable in comparison.

Some more numbers.

These six packs are brand new, never charged, just unwrapped and connectors added. I got the Loong max two months ago; they’ve been dry stored at ~ 5 centigrade. I got the Thunder Powers last week. I fitted 4mm gold bullets to the two 4s packs and 6.5mm CC bullets to the four 5s packs.

All were measured at home yesterday, ambient temperature 20 C (68 Fahrenheit) after having been at 20 degrees centigrade for 6 hours

Loong Max Tipple 4500mAH 5s 30C
Pack 1
Cell volts: 3.85, 3.85, 3.84, 3.84, 3.84
Cell IR: 3.04, 3.20, 3.16, 2.88, 4.28

Pack 2
Cell volts: 3.85, 3.84, 3.84, 3.84, 3.84
Cell IR: 2.44, 2.40, 2.64, 2.56, 3.96

TP G6 3300mAH 4s 65C
Pack 1
Cell volts: 3.82, 3.82, 3.82, 3.82
Cell IR: 3.96, 4.44, 3.92, 3.80

Pack 2
Cell volts: 3.82, 3.82, 3.82, 3.82
Cell IR: 3.92, 4.28, 4.12, 4.08

TP G6 5000mAH 5s 65C
Pack 1
Cell volts: 3.82, 3.82, 3.82, 3.82, 3.82
Cell IR: 2.74, 2.78, 2.86, 2.86, 2.78

Pack 2
Cell volts: 3.83, 3.83, 3.82, 3.82, 3.82
Cell IR: 2.66, 2.82, 2.66, 2.74, 2.62

The proposed uses are:
4s pattern at ~40-45amps WOT on the ground, 3D aero at ~55-60amps WOT on the ground, EDF at ~50-60amps WOT on the ground (which wont decrease on the air).
5s pattern at ~80-90amps WOT on the ground

edit: i'll add pack weights later and update on the numbers once a decent number of cycles have been put on the packs.

Alex
Alex,

Thanks Alex. I know it is true that most of these little 'Cell Checkers' are very unreliable on accuracy. Have been discussing it with Bob Smith and talking voltage references; suspect he is thinking of doing some testing on them, but only a guess.
Also thanks for posting the figures on the new packs The TP don't look any better overall than the LM but the cells look better matched. The real criteria is how long they last in cycles.
Just as an excercise I have taken your results and produced FOMs (Figures Of Merit) for each pack based on the suggestion of Mark Forsyth and my posting at http://www.rcgroups.com/forums/showthread.php?t=1392662
They work out :-
LM 4500 30C No1 0.87 No 2 0.95
TP 3300 65C No1 0.90 No 2 0.89
TP 5000 65C No1 0.86 No 2 0.89

Ideal is 1.00 or more but I think Mark is being a bit severe with his norm of IR x mAh being <12000

Am just about to do some comparative testing on 3S220025C and 45C packs (all new) and have taken IR readings (at 25Cent) and the FOMs range from 1.40 down to 0.59. I note that the Turnigy 45C Nanotech is exactly the same as the old Turnigy 25C 'Normal' at 1.15!
Will be interesting to see your pack results after a few cycles.

Wayne
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Old Mar 08, 2011, 03:37 AM
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The Netherlands, LI, Venray
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Quote:
Originally Posted by like2fly! View Post
edit: i'll add pack weights later and update on the numbers once a decent number of cycles have been put on the packs.

Alex
Alex what is the total pack resistance you measure of the lipo's?
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Old Mar 08, 2011, 06:45 AM
who dares wins
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London,England
Joined Apr 2005
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Quote:
Originally Posted by jaccies View Post
Alex what is the total pack resistance you measure of the lipo's?
Hi,

I didn’t list that as the meter has 4mm bullets fitted, but for the 5s packs im using additional adapters 4mm bullet – 6.5mm bullet, whereas for the 4s packs there are no adapters.

Is the info still useful?
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Old Mar 09, 2011, 04:06 AM
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Quote:
Originally Posted by like2fly! View Post
Hi,

I didn’t list that as the meter has 4mm bullets fitted, but for the 5s packs im using additional adapters 4mm bullet – 6.5mm bullet, whereas for the 4s packs there are no adapters.

Is the info still useful?
Always useful for comparison with my results.
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Old Mar 09, 2011, 06:03 AM
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Rugby, UK
Joined Feb 2007
896 Posts
Can I just stick my nose in here as I think the information is useful.
For comparison purposes it is always better to use the Cell IR as the Pack readings include the connectors + wires + interconnections + soldered joints and in total these are larger than you expect.
I was initially surprised at the average total of 6 - 8 milliohms as a Deans, XT60 or a couple of 4mm bullets are about 1 - 2 milliohms.
Just to highlight how much difference there can be, I am at present power testing some packs with Deans connectors and one pack showed >16milliohms difference. It turned out that ONE solder joint on the Deans connector was 12.2 milliohms. It was not a dry joint, but just with a small overlap and minimum solder. Power dissipation at max rated current in the joint would have been 37Watts, enough to unsolder it (or resolder it!) within about 20 -30 seconds.

Wayne
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Old Mar 09, 2011, 03:53 PM
who dares wins
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London,England
Joined Apr 2005
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Hi,
Pack IR's added to my post above. These were taken at the same time as the cell IR's.

Would you say my solder joints seem ok from an IR point of view?

Alex
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Old Mar 09, 2011, 05:42 PM
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Rugby, UK
Joined Feb 2007
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Alex,
They do look a little high, but they look consistent in pairs; ie the same types look fairly close. There is a potential error if you took them at different times and slightly different temperatures as we are looking at a small difference in two larger numbers so any error in the large numbers is magnified.
I don't think you have any soldering problems there, the 12.2milliohms I found was on a single joint, so that a cell total of 16milliohms with a pack reading of 34.5 milliohms showed an obvious problem.
It did mean that I found a hidden problem with the meter which otherwise could have been found the hard way.

Wayne
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Old Mar 10, 2011, 03:25 AM
who dares wins
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London,England
Joined Apr 2005
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Quote:
Originally Posted by Wayne Giles View Post
Alex,
They do look a little high, but they look consistent in pairs; ie the same types look fairly close. There is a potential error if you took them at different times and slightly different temperatures as we are looking at a small difference in two larger numbers so any error in the large numbers is magnified.
I don't think you have any soldering problems there, the 12.2milliohms I found was on a single joint, so that a cell total of 16milliohms with a pack reading of 34.5 milliohms showed an obvious problem.
It did mean that I found a hidden problem with the meter which otherwise could have been found the hard way.

Wayne
Thanks Wayne. The readings were taken at the same time as the individual cell readings.
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Old Mar 10, 2011, 09:04 PM
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Joined May 2003
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Please put me on the list and PM me payment details (assume PP is OK, mine is backed with CC -is that OK? don't trust the blighters w/ bank account)
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Old Mar 10, 2011, 09:12 PM
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United States, IL, Peoria
Joined May 2003
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BTW, spent several months in Leicester/Desford on 2001/2 working on LandRover parts with Caterpillar. Looks like I wasn't far from Rugby-may even have driven through it once - we spent a lot of time flying in/out of Birmingham. Fond memories of getting passed on the right, and doing roundabouts-Most Americans don't get them, but I did, except Hemel Hempstead- too many lanes!
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Last edited by speed2004; Mar 10, 2011 at 09:13 PM. Reason: spelling
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Old Mar 12, 2011, 11:59 AM
D C
I'm Out Sky Dancing!
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United States, TX, Bryan
Joined Jan 2009
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Quote:
If anyone else is in the market, please let me know; I don't mind taking some risk, but not much as there is no profit motive involved

Wayne.
Please put me down for one too....

Don C
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