Safe Way to add additional batteries

[TechRider]

Hello,

I've got an existing DIY set of 48v LiFePO4 batteries with a JK Inverter BMS on each. (4 total batteries) They're also in closed loop communication with my Sol-Ark 15k. I'm looking to add 2 more of the same type battery to my setup and I'm looking for a safe way to add them without taking my system offline.

I've got a victron lynx power for my buss and will be adding another. Each battery connection is fused at that point. The BMS is set to limit charge/discharge to 100a for each pack. The batteries also have a disconnect on them and the new cables will be the same length as the original.

Here is my plan: (During a period of low battery use. I'm thinking around 1pm on a nice day when the batteries are full and there's plenty of sun left.)

1. Get all the settings on the 2 new batteries/bms correct and set charge/discharge to disabled.
2. Connect the 2 new batteries to the bus and make sure the inverter communication is working.
3. Make sure the original battery packs are all at 100%.
4. Disable discharge on 3 of the previous battery packs.
5. Close the disconnect on the new batteries.
6. Enable discharge on the new batteries. (This allows my Sol-Ark to still operate off the batteries without seeing interruption.)
7. Disable discharge on the last original battery.
8. Enable Charge on the new batteries. (The new batteries will now be charging from PV.)
9. Wait till everything says 100% / no real current flow.
10. Enable discharge on the original batteries.
11. Sit back and smile at 50% more capacity.

I've been through this in my mind a few times and it seems like this is a safe way to add the batteries without taking down my system.

Thoughts?

 

[42OhmsPA]

I think you've thought it out well and have a good plan.
My only question/concern, will the inverter communications override your charge and discharge settings?

 

[TechRider]

My only question/concern, will the inverter communications override your charge and discharge settings?

That's a good thought and something I hadn't considered. It should be pretty easy to tell, if I change the setting then it changes right back, I'll know. Thanks!

 

[Badbyte]

Another thing to note, most BMS boards will allow you disable/turn off charging only for a short time. After that they turn it back on automatically, timeouts vary on different bms boards, so please verify if that is also the case with your boards. Mine resets after 5 minutes. or so