MB31 balancing, which power supply/battery tester

[rgroothuis]

I've ordered MB31 cells (16x) they still have to arrive, no details on voltage yet. Assuming I need to balance them, which power supply or battery testing do you recommend? I've seen the blue device: EBC-A40L but this is another 200+ euro's. Any good alternatives?

 

[kommando]

I use the BMS active balancer which in my case is a JK PB.

 

[rgroothuis]

I use the BMS active balancer which in my case is a JK PB.

Ok, thanks for your feedback. The battery box I've purchase also has the JK BMS with a 2A active balancer. So you installed all the batteries into the box and switched it on and leave it like that for a couple of day? What was your process?

And was the charger/inverted already connected? And charging the batteries?

Can you provide a bit more details? Thanks.

 

[miran90]

Dear just connect them and charge no need for balancing they will eventually balance themselves after a few cycles.
I just assemble and charge.

 

[740GLE]

Ok, thanks for your feedback. The battery box I've purchase also has the JK BMS with a 2A active balancer. So you installed all the batteries into the box and switched it on and leave it like that for a couple of day? What was your process?

And was the charger/inverted already connected? And charging the batteries?

Can you provide a bit more details? Thanks.

Yup my SCC charging settings are very conservative, 3.45-3.5v per cell.

As long as you are able to maintain system voltage so that cells are above 3.4v for few hours a day your cells will be under 0.010v delta way quicker than doing top balance.

Set it and forget it.

 

[upnorthandpersonal]

Like other said: just put them in use when you have a JK BMS. They will get balanced over time, just make sure the BMS parameters and charge controller settings are correct.

 

[kommando]

Ok, thanks for your feedback. The battery box I've purchase also has the JK BMS with a 2A active balancer. So you installed all the batteries into the box and switched it on and leave it like that for a couple of day? What was your process?

Assembled the cells in case and allowed PV to do the charging, if you have no sun then you wait. If they are badly out of balance when you first get to 3.45V cell V or you are impatient then use a simple lab power supply to charge the low cell while the rest and the low cell are being charged by the PV. Any too high runners can be taken down by connecting a car bulb across the 2 terminals. Once they are in balance at delta 0.010V then take the delta down to 0.008V.

 

[740GLE]

Assembled the cells in case and allowed PV to do the charging, if you have no sun then you wait. If they are badly out of balance when you first get to 3.45V cell V or you are impatient then use a simple lab power supply to charge the low cell while the rest and the low cell are being charged by the PV. Any too high runners can be taken down by connecting a car bulb across the 2 terminals. Once they are in balance at delta 0.010V then take the delta down to 0.008V.

The other option is picking up an AC charger, you don’t need much current.

For the first charge slow and low does no harm. 5-10 amp and let it bake.

 

[miran90]

The other option is picking up an AC charger, you don’t need much current.

For the first charge slow and low does no harm. 5-10 amp and let it bake.

Cutoff current for those cells is 0.019 times its capacity at 3.45v and 0.05 at 3.65v so it will be 5.32A and 14 respectively. otherwise you are risking overcharging the cells.

 

[rgroothuis]

Cutoff current for those cells is 0.019 times its capacity at 3.45v and 0.05 at 3.65v so it will be 5.32A and 14 respectively. otherwise you are risking overcharging the cells.

Can you explain this in a bit more detail? Is this about the charging profile of the batteries? And when you need to stop charging?

 

[740GLE]

Cutoff current for those cells is 0.019 times its capacity at 3.45v and 0.05 at 3.65v so it will be 5.32A and 14 respectively. otherwise you are risking overcharging the cells.

And any quality charger will flop from CC mode
to CV mode as they get up to the charging voltage and current will fall off.

I use a very conservative charging voltage 3.45-3.5v per cell.

 

[digitaldoug]

Ok, thanks for your feedback. The battery box I've purchase also has the JK BMS with a 2A active balancer. So you installed all the batteries into the box and switched it on and leave it like that for a couple of day? What was your process?

And was the charger/inverted already connected? And charging the batteries?

Can you provide a bit more details? Thanks.

The ZKETECH 40L is a cell capacity tester. It is only used for 1 cell at a time. I.E. not for testing or using a 2..16 cell battery. It will measure the capacity (amp-hour, watt-hour) of a single cell very accurately. Sounds like you are new to the solar DYI game. The JK BMS needs a lot of configuration setup. I suggest you watch a few of the "off-grid-garage" videos on youtube. DLB

 

[JäseH]

I wired mine in 8S with a Daly BMS and charged to 3.5V with a 30V DC charger. Then I rewired in parallel and topped off to 3.6V. They settled after that, but after sitting for a few weeks I put them in a box and hooked them up. I've been monitoring them for the past few days and they're all within .005V using the Seplos 10E on my Apexium box. Of note, I also have a box with LF304 and the different in internal resistance is obvious, as the LF304 charge and discharge more slowly despite being wired in parallel. I kinda want to sell the LF304 for another 16 MB31 but the local supplier is out of stock again.