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Old Jan 04, 2006, 09:10 PM
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Joined Jun 2004
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Help!
Brand New 20C battery with only 4 flights will not charge to 12.6 volts

I have one of those new "Twenty" 20C 1200mah 11.1V lipos and I have 4 flights on it and I just tried to charge it using my Kokam LIPO-402 charger. I have the jumpers set to 1A and 11.1V. I'm using a Watt's Up meter to measure the charge rate and I connected it to power to start the charge and it quickly showed the amp rate fall to zero. The pack would only charge to 10.72 volts and it is supposed to be around 12.6 volts. Does anyone have any suggestions of what is going on. Could I have run the pack to low in voltage or could it be the charger?
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Old Jan 04, 2006, 09:23 PM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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Quote:
Could I have run the pack to low in voltage
What was the voltage before you tried to charge it?


Why not check the voltage of each cell?
Were you running it at 20C? Did it get hot, as in over 130F?

Charles
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Old Jan 04, 2006, 09:31 PM
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No, I flew it mostly at around half throttle or less not much full throttle except for a few full throttle climbs vertically but no more than about 3-5 seconds or so. The battery was slighty warm but not very warm, however, the temperature on a couple of those days was about 40-50 degrees.
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Old Jan 04, 2006, 09:33 PM
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The voltage was only around 10.7 volts when I started charging it, but it would not charge, don't understand what is going on.
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Old Jan 04, 2006, 09:41 PM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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Quote:
The pack would only charge to 10.72 volts
I thought perhaps it was lower to start with.
Most LiPoly chargers will not charge a battery which is below a certain voltage however 10.5 should be high enough for a 3S pack. It could be the charger , try a different LiPoly on the charger. Try the LiPoly on a different charger. Try charging without the watts up meter in -line.
Check the voltage of each cell.

Charles
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Old Jan 04, 2006, 10:01 PM
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Hey Charles, I think I found the problem, I forgot to mention my power source consists of a lawn mower battery So, basically I needed to charge the battery to charge my lipo. I was dumb, didn't think charging a lipo would drain my "power source" so quickly, but the batt must've been a little dry anyway. I hooked the "power source" charger and at a low current setting and then hooked my batt to it and it started charging and the voltage began to rise like it should. Can I ask you though, what exactly does it do if you do allow your pack to run lower than 9V only once or maybe twice by accident? Thanks for all your help Charles

---------------------------------------------------- Jason Campbell
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Old Jan 04, 2006, 10:12 PM
Southern Pride
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Haralson County GA. USA
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A resting voltage of below 3.7 volts per cell 30 minutes after a flight shortens the LiPos life. No hard data on how much but some which have gone down to 2 volts or so per cell hve lost 40% capacity. It also depends on how long the cells are below this 3.7 per cell.

Charles
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