Well... I thought I would cheat

[ericfx1984]

Well I decided to use my RC car charger and charge up my pair (2) 4s battery banks.. now just in case anybody was curious yes the charger does active cell balancing and it also has over voltage shut off. But it only does about 5-6a

Not really a huge deal.. but eventually you get to a point where you have one or two cells lagging behind quite a bit and it takes quite a while to do it this way I'm thinking I need to reconfigure them in parallel and put them on a bench power supply

Maybe I should bottom balance them while I am waiting for my bench power supply to come in the mail?.. this charger has a discharge function but I think it's limited to 2 amps per channel or I suppose another way I could do it is pop a 750 w inverter on the battery bank and hook up a 400 w heater that I have laying around?

 

[time2roll]

Has it stopped? I would keep running it.

 

[ericfx1984]

Has it stopped? I would keep running it.

It hasn't stopped.. but it's rolled back to somewhere between 0.2 and 0.5 amps I would imagine it is going to take quite a while to balance out

I suppose one way that I could do this is hook it up 2s on the two cells that are lagging behind that should allow them to charge at a faster rate but I suppose you're right I probably should just be patient already made it this far

 

[Horsefly]

Maybe I should bottom balance them while I am waiting for my bench power supply to come in the mail?

You should make a one-time decision for a pack if you want to use it based on a top balance or based on a bottom balance. Don't do both.

Most people here are using the cells for solar energy storage. By its nature, that use tends to spend more time near the top than near the bottom. For that reason most of us use a top balance. There's a resource here that explains the reasoning for top balancing.

 

[chrisski]

make a one-time decision for a pack if you want to use it based on a top balance or based on a bottom balance. Don't do both.

I agree.

With me, So much wasted time, money, and energy spent on other things “trying to do something instead of nothing.” Especially with my truck trying to fix things. I think you have perfectly good cells and just choose one way.

 

[ericfx1984]

I agree.

With me, So much wasted time, money, and energy spent on other things “trying to do something instead of nothing.” Especially with my truck trying to fix things. I think you have perfectly good cells and just choose one way.

Yeah I guess we're mostly through the top balance process.. this is just the most money I've ever spent on batteries in my entire life yeah.. so naturally I'm a little worried. The good news is the other 4S Bank balanced out pretty darn close

 

[time2roll]

It hasn't stopped.. but it's rolled back to somewhere between 0.2 and 0.5 amps I would imagine it is going to take quite a while to balance out

The specs I read said 500 milliamps balance current so as the cells top out this would be normal and expected to finish the last one at half amp.

 

[ericfx1984]

Not sure why I didn't think about this.. if I use the LiFe charge mode, rather than the balance charge mode I can charge the individual cells.. or, and I wish I had thought of this sooner, I could have also put all these cells in parallel and charged them on a single channel at 10a. Anyway oh well right

topping off the final cell that was lagging behind took 14 minutes and 58 seconds charging it directly as a single cell. That was to go from 91% to 100%