voltage and mAh - LiPo balancing Q

[hedonist222]

I picked up one of these and have a question.

My question applies to any LiPo charger really but here it is:

When you're balance charging the battery, it allows you to set

capacity cut off

end voltage cut off

Lets say the batter in question is a :

5450 mAh 2S 60C 7.4v

By default, the charger is set to :

capacity cut off 5000 mAh
end voltage cut off 8.4 (2S)


What my question is, can a battery reach 8.4v yet be 5000 mAh?

In my mind, for a battery to be fully charged at its rated capacity (5450 mAh in this case), the voltage has to reach 8.4v as well.

Otherwise if 5450 mAh battery is cut off at 5000 mAh, the voltage reached would not be 8.4v (4.2v per cell). It would be a bit less - maybe 8v.

Or can a battery reach 8.4v fully voltage charged and mAh be less than stated?

In my head, voltage reached and mAh have to be hand in hand.

 

[Greg]

I am not familiar with this charger, however, the video is so VERY self explanatory, I can't imagine why you need to ask any questions. Everything you need appears to be included, and the pictures tell you all you need to know. I told you yesterday, the charger will give you an audible beep, or some signal telling you the battery or batteries are finished. Since you have a multiple charger, there are separate screens used to set each battery, and each will tell you when finished. Even if you start them all at approximately the same time, they will finish at a little different time for each one but close together. You said you picked it up, so does that mean you got it at LHS? If so, for that kind of expenditure, why not ask how it works when purchasing? You worry too much about everything. Just plug in your charging cables to however many charging stations you will be using, that includes the balancing block (this block will generally charge different types of batteries and your battery balancing wire will only fit in one of the plugs) plug your battery to these wires, set the meter for that battery (being sure it's LiPo, if that is what you are using) generally hold the start button until it begins to charge, normally a couple seconds and a beep. The meter should start showing progress. Now continue to the next battery and repeat. ALL of this should be in the manual. Look at it!

 

[hedonist222]

Hi Greg, no I got it from Hong Kong.
But my post above yours wasn't about charger usage.

It was about battery dynamics.

Because I though the vehicle LVC would prevent a cell from going below 3.2v

But apparently it watches for the sum of cells - not individually.

 

[Jam Racing 1]

The LVC looks at overall voltage and decides based on that when to shut down, if one cell is weaker than the others then one may get discharged a bit more than the others, this is why balancing is so important with LiPo batteries......

 

[Greg]

hedonist222....not really important, you have what looks to be a very good charger, with all the bells and whistles. Stop worrying about all the specs and what-ifs and just go have some fun.

 

[faisalbasha]

i was told by my local hobby store that i didn't need to balance my 2s batteries, just the 3s.

 

[Jam Racing 1]

I would take that advice with a grain of salt, any LiPo using more than 1 cell needs to balance charge to keep the 2 cell as evenly matched as possible...

Besides being safe is way better than being sorry your stuff burnt down due to a bad cell letting go mid funtime....

 

[faisalbasha]

I've had 2s batteries without balancing for years and I've had no problems. I balanced them to check if the cells are the same and they were. This was once in 3 years

 

[Jam Racing 1]

Tempting fate is dangerous, it is your stuff and you have proven to not take good advice many times there failsafebasha, but I play it safe and do not take chances with my stuff.... when ya have the inevitable fire please post up the results for us all to see.....

 

[faisalbasha]

alright no problem

 

[X]

It is correct that you do not need to balance charge every time. However, if it is easily accessible to balance charge then there is no reason not to, you only benefit. A battery should always be balance charged the first few times of use, also every few runs. This also gets changed depending on how you discharge your batteries. If you do alot of quick runs, so the battery is not discharged significantly, then it is not as important to balance charge. However, if you run until battery cutoff, then it is quite important to balance charge because you run a higher risk of discharging unevenly.

 

[faisalbasha]

thanks for the explanation GHOST. I will balance charge every couple of runs on the 2s and on every charge for 3s which i already do anyway. I understand the core of balance charging.

 

[rcnut14]

OP, most chargers monitor the voltage, not the capacity. the capacity shut off is just a failsafe. I usually set the capacity just a little higher then the battery actually is.