Balancing using a power supply with no meters

[offgrider]

ETA: MY BAD... I meant to all do this in parallel, I saod 4s later down this post but thats not what I meant!

Ive got this really nice 13.8vdc 22amp continuous power supply I use for some of my ham radio equipment. It has no volt/amp meters indicators on it though. Would I be able to use it to top balance all 32 of my 280ah lifepo4 batteries, 4s 4p at a time?

Id rather not use a regular lab PSU everyone has as they just arent very powerful and I have 32 of these batteries which would take forever (345watts vs 18watts); its just be much quicker if I use this one. But I wonder about no built in meters.. Can I just periodically monitor the amperage with a clampon meter (or an inline ammeter)?

Or is it possible to let is sit for too long? I just dont want to mess these up.

 

[Ampster]

Four cells in series is most likely going to get you an occasional runner. Without a BMS you will only know when that cell has overvolted. You can be the BMS if you have the time. On the other hand if you have the time just parallel top balance and do not risk destroying a cell or two.
13.8 is 3.45 volts per cell which if they stay even will get you close to the top and then you can parallel top balance all of them to 3.65 volts. At that point you might only need 15 or. 20 Watts per cell or overnight to get a well balanced pack. The difference in capacity from 3.45 to 3.65 is probably only about five percent.

 

[HRTKD]

If you don't use a BMS when charging in the 4s configuration, you run a fairly large risk. I wouldn't do it. With a BMS, it's doable. But that just gets the cells charged to a certain level after which you still need to put the cells in parallel and do the top balance using 3.65 volts.

I did my top balance with eight cells in parallel to 3.65 volts using a desktop power supply. I thought the power supply was going to be a one-and-done device that would gather dust on my shelf. But I've used it for quite a few things.

 

[offgrider]

ETA: MY BAD... I meant to all do this in parallel, I said 4s up in the OP but thats not what I meant, I meant all parallel.

ive got a BMS to use for the solar.... this operation here/now is all just to top balance all the cells before I assemble them into a bank and connect that to the solark.

My question in the OP was really meant on: what do I look for here, since my PS doesnt have any meters? Do I just let each 4p minibank sit at 13.8v on that power supply until I see current drop to like .1 amp or what?

 

[offgrider]

and now I see my error.... a 13.8v PSU cannot do a 4p bank of 3.2v cells.

 

[HRTKD]

Nope, that power supply isn't going to work. In parallel, those cells have a nominal rating of 3.2 volts. 13.8 volts will fry the cells at that voltage.

 

[Ampster]

I am am not sure I understand the advantage of doing 4P at a time versus 32P at a time. To me it is a lot more time hooking up each 4P eight times. The biggest risk is using a 13.8 volt source without some failsafe mechanism to turn off power when voltage reaches 3.65 volts.

 

[Ampster]

... a 13.8v PSU cannot do a 4p bank of 3.2v cells.

Yes it can, the power supply will drop down to the voltage of the cells and give all the Amps it can. Yes without a cutoff mechanism to turn it off at 3,6 volts you risk frying the cells as @HRTKD mentioned. The voltage ramp is very quick at the top so unless you want to start baby sitting the cells when they reach 3.45 volts then I would not recommend doing it without some failsafe mechanism.