Dual battery banks and Sol-Ark communication (EG4 18kpv as well)

Forgive me for being lazy, I’m sure I could just call Sol-Ark and get an answer but hopefully this can help someone else long term. Additionally hopefully we can get a solid answer from both companies as the 15k and 18k are popular units. I fully understand you could just parallel two banks of batteries of the same type (lifepo4).

My question pertains to using more than one battery manufacturer and retaining battery/inverter communication. Why do this? With the incoming UL9540 requirements limiting a single battery bank to 20kWh, then a three foot separation to the next bank, I imagine some of us will have to get creative.

For me, I have SOK batteries from Current Connected and I have zero complaints. I have plenty of room to stack more on top of my gun safe, but I’d be “breaking the rules”. They are connected to the Sol-Ark and communicating perfectly.

So, I’ve considered adding something like the EG4 Power Pro on the wall below my inverter, this effectively doubles my capacity at an even better price, uses “dead space”, keeps things tidy and most importantly doesn’t leave easy access for a toddler to go play with high voltage power.

But then the question is, can either of these inverters “talk” to two different BMS’s at the same time? I’m not even sure how that’d work as I imagine one may call for ramping charging down while the other still calls for max charge, it’s not like the inverter can decide where electrons go. I was simply hoping for communication to help with state of charge calculations and to keep both banks “safe”.

Thoughts?

Picture for reference of my setup.

Second rack of SOK and daisy chain a long communication cable between them?

DIYrich said:

Second rack of SOK and daisy chain a long communication cable between them?

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It’s just a form factor issue. No great place to put them, especially without having easy to reach conductors for a three year old.

Watts Happening said:

It’s just a form factor issue. No great place to put them, especially without having easy to reach conductors for a three year old.

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I think ul9540 specifies locking cabinets.

Since you brought it up...

The inverter set's a 'type' for BMS controlled batteries. I would surmise that one may run into difficulties if the 'types' are different. MODBUS commands are about as standard as XML. It just describes how you format queries, but does not define any specific query. The EG4 communications hub was designed to basically convert what the battery sends to what a particular inverter might want to see. This is where you will have issues. Reading register 5 on a given BMS are likely to give you different parameters, like current voltage on brand a vs SOC on brand b.

One would think that it if your battery banks are reasonably close in value/spec (Which they should be if you are in the same class) and have BMS, the BMS should prevent over/undercharging of the units, within the parameters of their specification. The power side should not be as big an issue. For example the EG4 LP4's spec a float voltage of 54V, and a Bulk of 56.2 with a LV cutoff 47-44. If you have a different LP4 that is reasonably close to those numbers (should be, since the physical cells on the same chemistry should be identical) then the actual bulk/float/cutoff values should be close enough to allow them to operate on the same bus with no issues, but . . . Without the BMS talking to the inverter, you would probably want some other tools to keep up with the balancing stuff, ie, you are now taking over management of the batteries from the AIO like many on this forum already do. In this case you would probably want to manually set the thresholds on the inverter, and independently manage each bank using a tool, but ...

Someone feel free to correct me if I've made an incorrect assumption some where.

BMS communications works with all batteries sending information to a master battery. And the master battery talks to the AIO.
All batteries must be compatible with the master. For communications to work.
If you want all batteries in the loop.

Watts Happening said:

Forgive me for being lazy, I’m sure I could just call Sol-Ark and get an answer but hopefully this can help someone else long term. Additionally hopefully we can get a solid answer from both companies as the 15k and 18k are popular units. I fully understand you could just parallel two banks of batteries of the same type (lifepo4).

My question pertains to using more than one battery manufacturer and retaining battery/inverter communication. Why do this? With the incoming UL9540 requirements limiting a single battery bank to 20kWh, then a three foot separation to the next bank, I imagine some of us will have to get creative.

For me, I have SOK batteries from Current Connected and I have zero complaints. I have plenty of room to stack more on top of my gun safe, but I’d be “breaking the rules”. They are connected to the Sol-Ark and communicating perfectly.

So, I’ve considered adding something like the EG4 Power Pro on the wall below my inverter, this effectively doubles my capacity at an even better price, uses “dead space”, keeps things tidy and most importantly doesn’t leave easy access for a toddler to go play with high voltage power.

But then the question is, can either of these inverters “talk” to two different BMS’s at the same time? I’m not even sure how that’d work as I imagine one may call for ramping charging down while the other still calls for max charge, it’s not like the inverter can decide where electrons go. I was simply hoping for communication to help with state of charge calculations and to keep both banks “safe”.

Thoughts?

Picture for reference of my setup.

View attachment 166787

Click to expand...

Where did you purchase that wiring box below the inverter and what is it called? Sorry for being off topic.

Cotbone10 said:

Where did you purchase that wiring box below the inverter and what is it called? Sorry for being off topic.

Click to expand...

Wireway or wiring trough. Local electric suppliers carry them

Cotbone10 said:

Where did you purchase that wiring box below the inverter and what is it called? Sorry for being off topic.

Click to expand...

Often referred to as a “wire trough” at a local electrical supply company. Rather expensive for what it is.