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Old Sep 18, 2004, 10:33 PM
fmidgett's Avatar
Durham NC
Joined Jul 2004
3,669 Posts
Question
How to test Lipo capacity?

I have 4 Kokam 1200mah 11.1v packs I bought used. One had a bad (puffed up) cell when I got it. When hooked to Kokam charger all lights blinked indicating a problem. I took off the bad cell. Now charger indicates no problem on the 7.4v pack, but it only lasts about 30 seconds before running down. Another pack looks fine, charges fine, lights indicate normal operation, but it also only lasts about 30 seconds. Only one of the cells in this pack gets warm during use, yet all individual cells read the same.

Is there a way to know for sure which cells are good? (If any).Two of the packs work fine. Last for 20 minutes in my Christen Eagle. Is there a way to measure mah capacity besides running the battery for x number of minutes?

Thanks,

Fred
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Old Sep 18, 2004, 11:45 PM
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adamg's Avatar
Saskatoon, Canada
Joined Feb 2004
1,494 Posts
Even running the battery and recording time doesn't tell you mah directly, and a true constant current load is not an easy thing to come by. A decent charger will do what you need (Triton, etc).
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Old Sep 19, 2004, 08:23 AM
KEC
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Joined Feb 2004
65 Posts
Quote:
Originally Posted by fmidgett
Is there a way to measure mah capacity besides running the battery for x number of minutes?
Fred

I have started to experiment with the Medusa Research Power Analyzer Plus.

I attempted (but failed) to add a voltage graph for a discharge test that I did last night. I discharged a 1200mah 3s1p pack through a 20W 8ohm resistor and monitored it with the Medusa Research Power Analyzer Plus. It also plots current, power, amp hours, and watt hours.

I have also created the gender changer cables so that I can monitor charging.
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Last edited by KEC; Sep 19, 2004 at 08:25 AM.
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