Can I flip the switch?

[Bluedog225]

Proceeding nervously. I’m trying to put my 4 pack of SOK server rack battles into operation. Finally got them up to the place and wired them up. Jeeze they are heavy. I’ve not yet wired the inverter.

They have been stored for over a year in my office at home. I charged them up about 6 month’s ago.

I did not check the voltage before wiring them together.

I don’t anticipate they are off from each other by much. Can I flip the breakers and activate the bms? I’m hoping any differences in charge will work itself out without issue.

Thanks

 

[Steve_S]

They'll only balance out between themselves. You may see a spike if one battery is higher or lower than the rest but that should not last too long. Probably wise to check with a multimeter to ensure there is not too much difference.

 

[Bluedog225]

Roger. How much delta would be ok?

 

[Steve_S]

Roger. How much delta would be ok?

Well that kind of depends on the pack size AH and the BMS capabilities. Under 1.0V there won't be very much, but if 280AH or 100AH that could be a lot of amps. If its 100AH to 100AH then it will be less for shorter time. Ideally, getting a charger ready & online when you start the batteries, will let them take it from the charger, the lower packs will draw more while the higher voltage packs will take less until they balance out at near identical voltage.

 

[MiSh]

From the SOK manual:

Automatic Charge Equalization​

Most batteries require equalizing packs to a similar state-of-charge (SOC%) when connecting for the first time. This is often accomplished by fully charging all batteries that will be used in a system before hooking them up. With the SK48v100, this is not required and a complete waste of your time. The BMS has an innovative, built-in charge limiting circuit.

Automatic Charge Current Limiter​

The built in charge limiting circuit is a part of the battery management system (BMS). The charge limiting circuit prevents excessive charge current from causing a complete shutdown of the battery module, by using active electronics to reduce the incoming charge current to a safe level. The charge limiting circuit is automatically activated when charge current exceeds 100A. When active, the charge limiting circuit reduces the charge current to 20 amps and stays active until the current falls below 20A, at which point the limiter automatically deactivates.


The charge limiting circuit is truly revolutionary, as most competing batteries will block all charging when the over-current threshold has been reached, causing a battery connected to a charger to appear as full, however, it is a false reading and the battery is actually depleted.


Let’s use a practical example of how this would come into play; let’s say your batteries were nearly empty and you removed one from service at a low state of charge for some reason. Later that day, solar charged the rest of the batteries in your system and now they are nearly full. Now, you are ready to add the new battery to service, but the SOC% is very different. Now, instead of manually equalizing the pack with the rest, you can safely re-rack the battery, turn it on and everything will return to normal operation without any user intervention.

 

[Bluedog225]

Thanks. They were pretty close. Flipped the switch and no drama.