Lipo 3S Battery charging

[BarryC]

Is there a solution when you balanced charger detects a 300mv difference between cells and will not charge?

Barry

[spongehoobtank82]

How low is the battery? If you have run it really flat it won't charge, but there is a trick to revive it!

[tomhugill]

Have you tried balance mode? Second if you've run it under 3v/cell some chargers won't let you charge it. In this case you can use nicad mode to boost it up before charging it in lipo mode again. However, use with caution, supervise and make sure you charge in a pan or something metal.

[Dr Phibes]

Is there a solution when you balanced charger detects a 300mv difference between cells and will not charge?

Barry

If you do mean 300mv (.3v) this is quite a large difference. Lipo's are fully charged at 4.20v per cell (12.6v for a 3s) so if you have, say, 4.20v, 4.20v, 3.90v then this is a problem. If, alternatively, you mean (for example) 4.20v, 4.05v, 4.05v this is still too low. Both examples suggest either your charger is not balancing correctly or the battery is faulty.
Bear in mind that some chargers balance better than others and batteries vary too so I have often had small lipos end charging with something like, 4.19v, 4.20v, 4.17v on a 3 cell and this is generally fine.

A straightforward solution is to discharge the battery (to around 3.60v is fine) and balance again. Cycle this several times if necessary but, really, with a good balance charger this shouldn't be necessary.

[BarryC]

Hi Guys,

I think the battery is done! Measuring the voltage using a VOM at the balance plug the cells read 3.01vdc, 6.05vdc and 7.3vdc with voltage at battery plug 7.6vdc.

My charger is designed to charge only Lipo batteries so any of the "tricks" you've offered are not an option.

The charger has a fault detection circuit and when the LEDs flash 6 times then off then 6 and off........it indicates that the charge has detected a 300mv difference.

I connected the charger to another 3s Lipo and it charged fine. I have ordered new batteries!

Thanks for all of you help,
Barry