General Battery question

[mb-1953]

What is the maximum acceptable difference in the cell voltage of a 6s lipo battery? I have 12s battery (really two 6s under one wrapper), on one side there is a single cell that will not go above 4.03v when the others are at 4.2v, the other side also has a single cell that is 4.01v while the other 5 cells are 4.2.
Do I toss it or can I use it? Thanks.
Mike

 

[Derek]

My understanding is that each cell should be within 0.02v of each other. None of my 19 batteries are beyond that difference. How do you charge your batteries? Have you tried balance charging them at a 1C rating and see if they balance out better?

 

[mb-1953]

Someone gave me the battery, I have tried to balance charge it and discharge it but the imbalance is always there.

 

[murankar]

If i had to guess it could be a bad cell. Have you put a cell checker on the pack to see what its reading? You could even use a multimeter on the balance plug to check the cells.

 

[Lee]

If its the same cell on both packs, maybe its your charger balance port not the batteries?

 

[Tony]

If its the same cell on both packs, maybe its your charger balance port not the batteries?

This was exactly my thought as well. If it's the same cell, then I would suspect the charger and not the cell. You can do a voltage test of each cell to see what is going on, but the charger could damage the pack further if it's reading the same thing that you are seeing. What charger is it and do you have the money for a better one if it's one of the cheaper ones?

 

[murankar]

I think he said only one cell is not balancing not 2. If it is two then maybe the balace board is bad or the charger.

If its just one cell then it could be the cell is bad.


As you were i missed the second part. Go with what lee and tony said.
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[pvolcko]

IF you find that it is the charger giving you a bad reading on that channel, depending on the charger you can possibly calibrate the channel voltage. iCharger allows this for sure (I had to do it). Not sure on others, but I suspect FMA PL6/8/10 chargers would also support it somehow.

 

[Lee]

First you could try to charge them on a friends, or local shops charger. See if that makes a difference, before splashing out on a new one.

 

[sarconastic]

I have one 3s pack that I bought new had one cell down almost exactly that much. I cycled it a few times and it has started to come back. it is now within .03 volts. I have run it maybe 6 or 7 times in my V912 dropping until battery alarm triggers. But even balance charging was not working. it took the cycling to do it. I tried it on two separate chargers at varying rates too. Just be aware if you run the pack and that cell drops to much you risk your charger not wanting to charge it due to low voltage. My voltage alarm triggers a little higher than the recommended low voltage and I am fine with that. Watch for puffiness of the one cell though. A good indicator the pack will fail soon.

If you have the money just replace it, if not take caution when using and charging it. LIPO's are no joking matter.

Later

WOody

 

[mb-1953]

It is a different cell on each side, cell 4 and cell 6. I have tried different chargers with same result, I'll try cycling a few times before I toss it.

 

[mb-1953]

The cycling recommendation worked perfectly, thank you very much. Battery is good as new.

 

[sarconastic]

Glad to hear it. Sometimes it just takes time LOL.


WOody

 

[murankar]

Now go fly. Packs can be tricky when new. Its best to use them lightly for the first few cycles to break them in.

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[wolfman76]

It is a different cell on each side, cell 4 and cell 6. I have tried different chargers with same result, I'll try cycling a few times before I toss it.

Just remember to neutralize the packs before tossing them or it for safety there is a thread on the forum that givrs the proper salt to water mixture needed and long to soak it before safet to toss in the garbage

 

[wolfman76]

Didn't see your last post
... lol

 

[murankar]

Salt water is not the best way to do that. Get a head light from a car and hook that up instead. The head lamp will deplete the pack fully and quicker.

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[wolfman76]

Thought you had to soak in saltwater to neutralize the chemicals as to prevent a fire in the garbage

 

[murankar]

It will corrode the leads and may not dissipate the electricity before that happens.

I think his name is Patrick from Progressive RC sad that its not a good idea to do that.

Once the pack is discharged take it to a Radio Shak or battery recycling place. I think the saltwater is used to help deplete the current prior to tossing in the bin.


Rc heli nation episode 127. That is the almost 1 hour long interview with the owner of Progressive RC. Its a really good interview, it uncovers a lot of misconceptions about lipos.

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[wolfman76]

Oh ok good to know