Adding EG4 LifePower4 battery to existing rack (SOC) question

[wildbillpdx]

I currently have three LifePower4 batteries running on my EG4 6000ex, charging and discharging daily. I just purchased a fourth and want to add it to the other three. I know the SOC for all four need to be the same. What I need is a suggestion on how to best accomplish that. The 6000ex has AC in and charges from the grid when the battery SOC is at 30%. I'm trying to figure out how to get all the batteries to the same SOC...drain them all to 30%? Charge them all to 100%? I do have a ChargeVerter, but no AC connection for it, only my generator.

Suggestions would be most appreciated.

 

[DIYrich]

you want the same VOLTAGE, not SOC. SOC is only estimated. Charge the existing batteries to 100%. disconnect or turn off existing batteries. Connect new battery. Charge it to 100%. At that point they should be really close voltage wise. If not, bleed down one until they match voltage.

Note: Voltages settle after charging. So, Charge Bank A. Remove. Charge Bank B. Remove. Charge A again (top charging takes a few minutes). If they are close, you can parallel A and B.

 

[wildbillpdx]

So following your suggestion: chargeverter used to get new battery to 100% and shutdown battery. Let my solar or grid charge existing three to 95% then use chargeverter to get to 100% and shutdown. Use chargeverter to top up new battery again and then connect all together and to the inverter?

 

[DougfromdaUP]

Check out this thread:

Matching EG4 SOC when adding batteries?​

 

[DougfromdaUP]

I forgot to add:

Just get them within a volt or so. The overpotential voltage will quickly limit current and you'll be fine.

 

[wildbillpdx]

Check out this thread:

Matching EG4 SOC when adding batteries?​

I saw that but was looking for suggestions on how best to equalize the charges in the batteries. Don't feel like messing with a bunch of raw wires to do this.

 

[DIYrich]

So following your suggestion: chargeverter used to get new battery to 100% and shutdown battery. Let my solar or grid charge existing three to 95% then use chargeverter to get to 100% and shutdown. Use chargeverter to top up new battery again and then connect all together and to the inverter?

That should work. Get them within 0.10v of each other. If you can, turn off discharge of the batteries through the BMS. Set the inverter to charge. When they all are charging (above the voltage of the highest battery) you can turn on discharge.