Alright, here's the situation. I just got a brand new Thunderpower 4300mah 25c 4s sport pack and I'm charging it for the first time. I am using the BC6DX charger. It gets to full in 25 minutes and it says capacity of 860mAh. I restart the charge/balance process to confirm it stopes in 30 seconds and says 4mAh. Is the capacity the amount it put in? I thought the battery is 4300 mah.

How do you assess the health of the battery. Is it through voltage? Each cell shows 4.19 volds and battery volume of 16.75 volts.

Is the 'health' of the battery not the capacity? Because that tells you how long you can run it for, correct?

I thought I had an unhealthy, low capacity battery so I called thunderpowerRC and they were useless, just telling me to send it in. I referred to the user manual, but it just says the mAh is capacity, but doesn't indicate if that's the total capacity of the battery.

So frustrating. Thanks for your help in advance.

Hi, your charger is telling you how much charge have been put into the battery.

First lets start at the beginning...

LiPo batteries are very sensitive to voltage.

Nominal average voltage per cell (1s) is 3.7 volts
2s = 7.4v
3s = 11.1v
4s = 14.8v

LiPo's are charged to a peak voltage of 4.2 +/- volts per cell.
Never run a LiPo below 3.0 volts per cell, just don't ok...

The charger will show you how many Milli-amp hours (mAh) you've put in, but that is dependent on how dead the battery is.

If you ran the pack down to 3.0v per cell then you'll be able to put a lot of mAh back into it.
If you run it for a couple of minuets you'll only get a little back into it.

LiPo's like to be stored at 3.7-3.8v per cell

A bad LiPo will manifest its self as swelling/puffing &/or diminished capacity.
If it will not peak properly voltage wise, or does not run as long as it should in the car/truck then you should become suspect.

Balancing (in my opinion) is important. The more cells the pack has the more important it becomes.
Balancing is cheep insurance to extend the life of any pack & once you have a balancer it is free to do every time.
Sounds like your charger likely has it built in... bonus.

this is just the tip of the iceberg...

Thanks a lot for your help. So I guess, if it's showing 4.2v per cell, it's possible everything is alright at least from a power perspective. How do you tell from a capacity prospective?

Maybe take a little time and read this -

http://www.rchelicopterfun.com/rc-lipo-batteries.html

You could do a discharge/charge cycle on your charger if it supports that function, or just run it. Make sure your ESC is set for low voltage cutoff though. Many batteries recommend taking it easy on the batteries for the first few charge cycles for break-in, it's worth checking on.

Everybody has been so helpful--greatly appreciated.

That charger (BC6DX) does have a discharge function but it has only a 1amp and/or 5watt discharge capacity whichever comes first, so discharging that lipo would take days. Running it would be far more effective and timely.


You don want to take it easy the 1st few cycles - don't run it hard enough to make it get warm or hot, thats bad for longevity.