Battery Bank per Inverter

Giving the limitation of 115A charge current per 6000xp inverter and the 100A internal BMS of the EG4-LL | 48V battery. Does it make sense to have a battery bank for each inverter? My plan is to start with 3 EG4-LL per inverter, 3 inverters. What do ya'll think?

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Typically LFP chemistry is charged at a lower current than discharge, 0.2C which is 20A per battery or in this case 60A for a set of 3 so 115A available per inverter is not really a limitation.

If you are paralleling 2 or more inverters do not use separate battery banks.
All brands want you to connect the inverters to a common battery bank.

1 busbar with equal length cables to teach group of batteries.
Also equal length DC cables from said busbar to each inverter.

You can Parallel AIO's to incxrease their output but also their generation capacity as well. Most brands like MPP/Growat/EG4 can also be networked so they work together.

Batteries can also be put in parallel and they will divide both load & charge between them proportionately to their capacities.
When paralleling battery packs, it is essential to use identical cabling (AWG) and identical lengths between them all.... Otherwise charge/discharge imbalances will occur. Most notably when charging, you will see different packs taking different voltages, the difference is an indicator.

Every Battery Pack should be Fused or be Breakered.
Below is a one of my generic diagrams showing how a paralleled AIO system is setup.
- You can have as many batteries as you want in a Battery Bank.
- They can also be added over time as there is no issues with doing so using LFP.
- The only constraint is the capacity to charge the Bank (remember the batteries divide load/charge between them)
- For ESS (Energy Storage Systems) most folks will charge their banks around 0.2 - 0.3 C Rate on average.
48V100AH Battery can take 0.5C / 50A Charge. 0.2C = 20A & 0.3C = 30A

! We have several members running 4-6 EG4 Batteries in a Rack as 1 bank to a single EG4 AIO, when using the same "Product Family" it is best of course to use the Battery to AIO Communications for a Closed Loop smart system.

For Clarity:
A Battery = a Set of Cells + a BMS built into an independent "Battery Pack".
A Bank = a Set of Complete Batteries assembled together to deliver more storage capacity (AH). This can be either/or series/parallel batteries.



Hope it Helps, Good Luck

What you want is fine, but you still might want one shared bank.

I had a setup like you described but changed it by paralleling the batteries in one large bank.

Paralleling the batteries, effectively make one large battery, and connect the inverters/chargers to this large battery could be more efficient.

In such a setup you are able to use all available storage by the connected inverters. So if one inverter uses a bit more, it will take power from 'the pool'.

This applies also for charging. All available pv is used.

In a setup with different banks, it is possible that one battery is already full and this inverter stops taking PV, while the other still is charging. Sharing the batteries into one pool prevents this.

So from a efficiency perspective, I would build a setup with a large shared bank.

FarmerSteve said:

Giving the limitation of 115A charge current per 6000xp inverter and the 100A internal BMS of the EG4-LL | 48V battery. Does it make sense to have a battery bank for each inverter? My plan is to start with 3 EG4-LL per inverter, 3 inverters. What do ya'll think?

​

Click to expand...

Connect the three stacks of lls to a single bus bar, same with the three inverters. Same cable lengths for inverters, same length for batteries. At max charging output the three inverters will do 345A of charging to 900Ah of batteries so should be in the sweet spot. The eg4s aren't recommended to be charged at 100A.

Robbert said:

What you want is fine, but you still might want one shared bank.

I had a setup like you described but changed it by paralleling the batteries in one large bank.

Paralleling the batteries, effectively make one large battery, and connect the inverters/chargers to this large battery could be more efficient.

In such a setup you are able to use all available storage by the connected inverters. So if one inverter uses a bit more, it will take power from 'the pool'.

This applies also for charging. All available pv is used.

In a setup with different banks, it is possible that one battery is already full and this inverter stops taking PV, while the other still is charging. Sharing the batteries into one pool prevents this.

So from a efficiency perspective, I would build a setup with a large shared bank.

Click to expand...

Thanks for the response. This is exactly what I was looking for basically a pro/con for individual banks or one.