Adding new SOK batteries

[vsman]

I just got my additional 5 SOK server rack batteries!!! Need some expert advice on how to commission it to my current Sol-ark-15k + 5 SOK battery setup.
This is what I understand needs to be done

1- shut down current battery bank.
2- turn of battery breaker at inverter
3- connect new battery bank
4- flip on breakers at inverter
5- flip on breakers at battery
6- turn on BMS

Question-
- Do I need to switch of entire inverter?

 

[HighTechLab]

Nope, your good to go based on the process you outlined.

 

[DIYrich]

The batteries should be at the same voltage when you connect them together.

What I find also helps is charge both batteries to 90%. Turn on system with one battery turned on. After it starts charging battery one, turn on battery two. They will then both start charging. Instead of one battery draining to the other, you now have a charging differential to the batteries that will even out at full charge.

 

[vsman]

The batteries should be at the same voltage when you connect them together.

What I find also helps is charge both batteries to 90%. Turn on system with one battery turned on. After it starts charging battery one, turn on battery two. They will then both start charging. Instead of one battery draining to the other, you now have a charging differential to the batteries that will even out at full charge.

Understand- but-
1 - with the communication setup- when I turn on one battery- all turn on.
2- is it necessary? Won’t the sol-ark/ BMS manage to get all into balance?

 

[DIYrich]

Understand- but-
1 - with the communication setup- when I turn on one battery- all turn on.
2- is it necessary? Won’t the sol-ark/ BMS manage to get all into balance?

The issue is initial balance. If you connect them in parallel, the higher voltage battery will supply full current to the lower voltage battery. The most the bms can do is cutoff battery output on one battery and input on the other battery. Better to do it yourself than to hope the bms does it fast enough to keep the fuse from blowing.

I suggest not connecting communications to battery 2 until after you turn it on.

 

[Watts Happening]

I would certainly make sure they are very close in state of charge when initially doing the parallel connection. You don’t want one bank at 50% and the other at 90%. You’re just looking for problems there.

Either charge one up or discharge the other, get them as close as you can and you’ll be just fine. Otherwise your plan looks solid.

 

[Supervstech]

Nope, your good to go based on the process you outlined.

So...
You don't think having the banks is the same or similar state of charge is important?
His current bank could be near zero, or at 100%SOC the new set likely is around 50%, since they were shipped to him.

Shouldn't he bring each set up to 100% first, before connecting the sets together?

 

[HighTechLab]

So...
You don't think having the banks is the same or similar state of charge is important?
His current bank could be near zero, or at 100%SOC the new set likely is around 50%, since they were shipped to him.

Shouldn't he bring each set up to 100% first, before connecting the sets together?

Doesn’t matter. The batteries have a charge current limiter so even if they were in this state the BMS would limit current to 20A until it tapers down below 20, at which point the limiter turns off.

Lithiumsolar made a video on this on his channel.

 

[vsman]

Hooked it all up- switched on- no issues.

https://imgur.com/a/NNUrZhu

 

[Bobguy]

Hooked it all up- switched on- no issues.

https://imgur.com/a/NNUrZhu

Wow that looks nice! Just bought the same. Any problems or advice?