1 bad battery in my 8s setup. Need advise please :)

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beefy nugz

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Arrma RC's
So I’ve got a cpl batteries, power hobby 4s 6600mah 75c soft packs. There about 3+ years old. One works perfectly like new the other, 3cells are perfect but one bad sale won’t charge past 3.53v.

so I need a new battery. Do I have to match brand/mah/c-rating on the new battery with the old battery that’s still good or does it not matter as long as it’s 4s???

thanks again guys!!!
 
For sure you need at least to match the battery capacity (in mAh) Otherwise, you risk having the smaller battery getting discharged too low before you hit LVC, and this battery will be ruined.

Interested to see what other will have to say. I remember reading on the forum that many prefer to have matching battery sets, purchased new from the same batch and always used together so that they have the same "history". Once one goes bad, you use the remaining battery in a single-battery car. This is what I do, out of precaution.

I am sure the Lipo experts here will have good recommendations.
 
Well once any cell reaches 3.7-8v lvc should kick in. Your other battery might still have 80% juice, just won’t be used
 
Doesn't the ESC only monitor the average voltage from all cells? I don't see how the ESC could know the voltage of individual cells.
 
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Doesn't the ESC only monitor the average voltage from all cells? I don't see how the ESC could know the voltage of the the individual cells.
Only very fancy ESCs have that capability, aka very few are able to.
The ESC will just hunt for (Cell count * LVC) voltage
 
Replace both. If they are over 3 years old then pairing a new battery with the old one thats still good will just kill the old one anyways.

The reason you buy in pairs is so they both have the same cell wear. Internal resistance will.go up with cycles and age. Putting a new battery with a good but worn battery will have the weaker old battery discharge lower than the new battery.
 
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