LIFEpo4 cell charging question

[MKalman]

Hey there,

I currently have 16s of 3.2V EVE LIFEpo4 cells, I am wondering if it is okay to charge them in series to bring them up to around 80-90% and then disconnect and do a top balance on the 4 sets of 4 cells? Is this an okay way to do things? And what voltage should I keep my bench power supply at for this battery? Is 58.4V okay?

 

[Nobodybusiness]

Hey there,

I currently have 16s of 3.2V EVE LIFEpo4 cells, I am wondering if it is okay to charge them in series to bring them up to around 80-90% and then disconnect and do a top balance on the 4 sets of 4 cells? Is this an okay way to do things? And what voltage should I keep my bench power supply at for this battery? Is 58.4V okay?

Why not just charge them in Parallel?
Set for 3.65 Volts.

I don’t see any reason you can’t do it the way you are saying.
Just curious why?

 

[DerpsyDoodler]

Hey there,

I currently have 16s of 3.2V EVE LIFEpo4 cells, I am wondering if it is okay to charge them in series to bring them up to around 80-90% and then disconnect and do a top balance on the 4 sets of 4 cells? Is this an okay way to do things? And what voltage should I keep my bench power supply at for this battery? Is 58.4V okay?

Unless you have a 16s BMS to protect them with, I suggest not. It's one of those situations where you might get away with it, but that would generate a false sense of security and is not a recommended practice. When these cells start reaching full, the voltage climbs quick.

 

[MKalman]

Unless you have a 16s BMS to protect them with, I suggest not. It's one of those situations where you might get away with it, but that would generate a false sense of security and is not a recommended practice. When these cells start reaching full, the voltage climbs quick.

Okay, so I will discontinue charging right now and wait till the BMS comes. No problem doing it with the BMS though, once set up of course?

 

[MKalman]

Why not just charge them in Parallel?
Set for 3.65 Volts.

I don’t see any reason you can’t do it the way you are saying.
Just curious why?

I already have them in a compression case and they're heavy as. Is laziness the right answer? To get in parallel I'll have to loosen them and they're already in a pelican case.

 

[DerpsyDoodler]

Okay, so I will discontinue charging right now and wait till the BMS comes. No problem doing it with the BMS though, once set up of course?

No problem at all.

 

[MKalman]

No problem at all.

Awesome, I'll wait until the JBD 16S comes and plug it in according to manual and bring it up closer to what it needs to be, what is considered around 90% full with a 16S pack so that I don't go too far and I leave enough room to top balance?

 

[DerpsyDoodler]

Awesome, I'll wait until the JBD 16S comes and plug it in according to manual and bring it up closer to what it needs to be, what is considered around 90% full with a 16S pack so that I don't go too far and I leave enough room to top balance?

i *think* 90% is 3.35v per cell. So in a 16s pack 3.35 x 16 would be the voltage to set your charger at. Furthermore, if your BMS has built-in balancing, once you start getting into the upper knee, limit your charge current to 5 amps and gradually step it down. This will give the BMS balancer a chance handle the top balance. If its a passive balancer it will be a very low balancing current so you may need to limit the charge current to 1-2 amps in order for it to keep up.

Make sure you scuff the terminals with fine grit sand paper and clean with isopropyl alcohol right before making the bus bar connections. I also suggest oxguard or noalox to help protect from corrosion.

 

[Nobodybusiness]

Okay, so I will discontinue charging right now and wait till the BMS comes. No problem doing it with the BMS though, once set up of course?

I was unaware you didn't have a BMS. Probably not a good idea then..