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Checking voltage while charging 7.4v li-ion, Showing 10.35v and rising?

Old 08-15-2008, 04:31 AM
  #1  
mescalinedreamz
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Default Checking voltage while charging 7.4v li-ion, Showing 10.35v and rising?

Im new to li-ion and read that a 7.4v li-ion pack shouldnt be charged passed the 8.4v mark. Well i have now charged two different 7.4v packs on two different li-ion dedicated chargers and both chargers are still pushing the voltage up past the 10v mark and still arent finished charging. Is this right? The batteries arent warm and this is the second time i charged them. The first time i didnt charge them until the charge light went out. I just took them off the charger then used them in my litestick. I decided to check the voltage after about 45 minutes on the charger. Both chargers take 1 hour to charge them. The voltage is10.43 and the charger just shut off. So is this correct? This 1 that i just charged is the xpv battery with xpv charger. Its showing on my voltage meter set on 20vdc setting 10.43. Im a bit confused. Thanks
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Old 08-15-2008, 07:31 AM
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marchino61
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No, this is not correct. I suspect there is something wrong with your measuring equipment....

....of course, mescaline can also have a very similar effect on batteries
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Old 08-15-2008, 02:16 PM
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mescalinedreamz
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Im thinking the same thing, It seems odd that now in the morning that both packs are reading 8.40 Its like a weird dream man
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Old 08-15-2008, 04:54 PM
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soar-ne
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I have found that the economy DVM s from Harbor freight (red& yellow ones), when the 9v battery starts to die the voltage will be reading high like your shows. If you leave them on for a while they mess up but the battery will kind of recharge if left off for a while and then read correctly. Try changeing the battery inside the meter!!!!!
Bet your little stick flys better with the lipos doesnt it.

Happy flying
Bob
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Old 08-16-2008, 12:37 AM
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mescalinedreamz
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Definitly better! I bought the xpv battery and charger from toys r us. It said 10.98 and was the last one. I took back that rc pterodactle thing and got a gift card. Anyways to my suprise the charger/battery came up to 2.70! What a deal for a lipo and charger! I then went to radioshack and bought 2 1550mah 3.7v packs cell phone batterys at 2.97 a peice. The battery i was talking about in the post above was a digital camera 7.4v 1400mah li-ion that i got from radioshack for 4.97. Im checking voltage right now while the xpv battery charges again. I already used it up trying to figure out how long it would run mwith the plane on full throttle/mid throttle etc in my hand(too windy for the stick) Im checking voltage with a new 9v battery in my craftsman digital multimeter. I cant wait til the wind dies down!
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Old 08-16-2008, 01:54 AM
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no, i was right. Well my volt meter is right. The xpv li-ion battery on a dedicated xpv charger is showing 8.49v on the 20vdc setting and its still chargging. The other battery topped off at 10.40 something today. This battery is supposed to charge in one hour. I really need to time it.
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Old 08-16-2008, 02:08 AM
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weird , stopped at 8.49?
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Old 08-16-2008, 02:13 AM
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Murocflyer
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Voltage in LiPo cells can be broken down like this:

4.20v = 100%
4.03v = 76%
3.86v = 52%
3.83v = 42%
3.79v = 30%
3.70v = 11%
3.6?v = 0%

According to Jeff at CSRC. If you are exceeding 4.2V per cell, something is wrong and you are most likely slowly destroying your batteries.

Frank
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