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Old Apr 12, 2012, 07:52 AM
Whoooo!
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Summerville, SC
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To add to what Hoppy said, I usually charge it JUST long enough to get the lipo charger to accept the battery again. This usually does noA t take very long at all. A 1-5min. Charge at the lowest amperage possible when bringing it up, and continue with a low amp charge once switching to the lipo charger.
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Old May 14, 2012, 12:23 AM
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thank you OP!!
i am the new starter of flying, these are really what i need!!!
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Old May 26, 2012, 03:10 AM
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I have 3 lipos... 2 - 2200mah 3s and 1 - 3000mah 4s. I bought them a year ago and the have lived in a soft material lined aluminum case along with around 10 other batteries. I have around every 3 or 4 months put them all on balance charge to top them up. The three aforementioned batteries have never been used, but become puffed and completely dead some time in the last 3 months... I mean by dead the cell tester won't even light up. What happened do they have a shelf life and why didn't any of the others (some older) not do this? Any help would be appreciated.

Larry
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Old May 26, 2012, 12:30 PM
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They do have a shelf life but additionally they should not be stored fully charged. LiPo's should be stored at approximately 3.8-3.9 volts per cell. The exact voltage is not important as long as it is near the 50% charge level. Storing fully charged or near the lower limit of 3 volts per cell are both bad and cause accelerated damage.
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Old Jun 04, 2012, 07:29 PM
I think I'm inverted. Maybe.
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I don't have a NiMh charger that I can adjust the current/voltage on. I do have a NiMh charger that can either put out 9.6v or 4.8v. For a 2S battery, would either of those work?
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Old Jun 04, 2012, 08:07 PM
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What is the voltage of each cell now? If you don't know that, what about the pack voltage?

Next question - what is the current output from the chargers? Is it variable?
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Old Jun 04, 2012, 08:38 PM
I think I'm inverted. Maybe.
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I think both cells are sitting at about .8 volts. The charger is an old Hitec NiMh charger for my 72mHz. It charges at 80mAh. If those don't work, that's fine. I'm getting a better charger soon that has NiMh capability. I just don't know the optimal voltage for jumpstarting a LiPo.
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Old Jun 04, 2012, 11:47 PM
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That's very low and the cells are probably irreversibly damaged.

I'd replace the pack. I don't recommend it but the tx charger could be used to get the cells up to 3.2v/cell..... when doing this, you have to monitor the voltage continuously so it doesn't go much above 3.2v/cell. If the pack has or does puff, don't even try this procedure.

Be careful, the pack is now damaged goods and therefore more dangerous to use.
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Old Jun 12, 2012, 03:36 PM
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evening gents/ladies'
I am at present trying to recharge a cheapy hong kong 2200 2s battery that I stored fully charged about a year ago and forgot about, due to moving house the output from the pack was about 2.4 volts so pretty knackered , so if it charges up all well and good if not it goes into the recycle bin at work....... Iconnected it to my old JP (celectra) 1-3 cell charger , the output was so low the cells wouldn't accept a charge and the charger went off line... I then thought I'd try charging as a single cell lipo and see if the cells would take a charge.... this they did ...left it on the charger for 15 minutes,charging at 500 m amps then flicked the cell switch to 2 cells ....didnt work the first couple of timesbut eventually the charger went on line .... I am sitting here watching the voltmeter sitting around7.7 - 7.8 volts , the charger is working and hopefully I'll have a charged cell back. It is however not staying indoors tonight....
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Old Jun 12, 2012, 03:44 PM
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scotland
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Just tried it on polly pusher fuz that I'm in the process of rejuvenating, after 20 minutes charging.......it wasn't even turning the prop last night, spinning the motor fine now , so a supervised charge session in the open tomorrow... will let you know if it works
gordon
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Old Jun 13, 2012, 02:36 PM
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the battery seems to have taken a full charge and held it......I trickle charged it at 250m amp all day the volt meter was readind8.4 as the charger switch off so , maybe we can bring lipos back from the dead............. tomorrow there is a rc smart 7.4 2700mA that was sitting in my GWS c130 hanging on the garage wall.... Its been there wfor over a year but was left charged , and unplugged it was reading 7.8 after a minute on the charger so in a safe area at work it will get the full trickle charge treatment .... wish me luck....... by the way, I'm scottish hence trying to salvage cheap batteries.... my wife says I'm as tight as a gnats chuff
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Old Jun 13, 2012, 03:41 PM
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What did the first battery read 2 days later?
1st day - 8.4V
2nd day - ?V
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Old Jun 14, 2012, 02:54 PM
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Quote:
Originally Posted by hoppy View Post
What did the first battery read 2 days later?
1st day - 8.4V
2nd day - ?V
7.4 this evening Hoppy....... may well have saved it .... but not fo use on anything valuable
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Old Jun 14, 2012, 03:18 PM
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That's what I expected Gordon. It's a goner. If you did a capacity check you would find it to be quite low. A good lipo will drop voltage very very slowly.

But experiments are always fun.
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Old Jun 20, 2012, 04:22 AM
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Singapore, Singapore
Joined Apr 2012
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Quote:
Originally Posted by hoppy View Post
What did the first battery read 2 days later?
1st day - 8.4V
2nd day - ?V
very very dead
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