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Why a 2s 7.4v Lipo Charges to 8.4v?


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#1 SeniorXJ

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Posted 29 September 2018 - 06:00 AM

I have a 2s 1000mAh graphene lipo and a hobby grade charger. It always charges to 8.4v and I've always wondered why?
My 3s 11.1v Tato lipo also charges to 12.4v. Anyone know why this is?

Thanks
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#2 snakerbot

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Posted 29 September 2018 - 01:19 PM

3.7V is the nominal voltage, around where the battery spends most of its lifespan. Look up lipo discharge curves and you'll see that they lose voltage very quickly early in the discharge cycle, then flatten out for a while and stay near 3.7V for most of their life, then drop off like a rock again at the very end. Full charge for a lipo cell is 4.2V.


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#3 shandsgator8

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Posted 07 October 2018 - 03:49 PM

snakerbot is exactly right. I'd like to add that the voltage during a discharge will also depend on the rate of discharge. Under high loads, batteries will experience "voltage sag" which can sometimes lower the voltage of the battery past its nominal voltage rating. Batteries with high internal resistance will tend to do this more (and get warm/hot).


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