Multiple Batteries and Multiple Inverters

[teal95]

I have a SolArk 15k with 6 strings of 7 panels and a rack of EG4 LL batteries. This is a split phase system feeding lights and outlets in the barn and most of my house. This is the easy part.

Now I'm adding 3 EG4 6500ex's to make 3 phase, and another rack of LL batteries. The first rack of batteries I'm keeping the comms to the SolArk for control. For the 6500's I see 2 options for battery control. Either I connect the second rack of batteries comms to the first and have the 6500's run voltage control or I have the first rack comms to the SolArk and the second rack comms connected to the 6500's, even though the battery outputs will be tied together. I'm leaning towards the comms being all together to the SolArk but I'm not sure that's the best answer.

Some of the PV will get moved to the 6500's. I have some shading issues and I believe the optimizers are fighting on the strings that are paralleled.

 

[timselectric]

It's really just personal preference.
Either way will work.

 

[teal95]

Since I'm ready to power up the first 6500 and the second battery hasn't shipped I'll use the voltage method. Unless I have issues it will probably stay that way.

What should I use for the max voltage for charging? Is 56 reasonable? I'd just look at what the voltage is when it's fully charged and subtract 0.5 but we're severely overcast today so it's not going to get full.

 

[BentleyJ]

56.0V is 3.5V per cell for a 16S battery. Its just not necessary to charge at often recommended manufacturer higher voltages. Keep the charge current down to 0.2C.

 

[timselectric]

Anything above 55.2v is fine.
Higher, charges and balances faster.
But it all depends on the quality of the cells. And how well balanced they already are.

Ditto, on 0.2c