Schneider XW Pro LBCO & current question

[pvdude]

Wondering if I should change the LBCO, and/or some other values?
Situation:
Grid went down about noon.
We switched the house over to solar via the giant transfer switch.

Shut off all the breakers for non-essential loads, so as to prolong battery charge.

Schneider alarm!

I forgot that the water heater timer was configured to run at noon.
Uses 6kw for about an hour to heat up 80 gallons.
(Normally, the PV powers this event.)

Took me a few minutes to realize the situation, and disconnect the water heater,
after which the house load was reduced to the normal 800w vs 6500w.

Anyway, I expected the Schneider system to tolerate 120A battery draw w/o complaint.

Looking for suggestions as to what adjustments I could make to source more amps from the batteries w/o the system freaking out.

 

[Solar Guppy]

The issue is not the inverter but your battery bank, 6kw is 125 amps @ 48V, so what size and type of batteries do you have?

 

[pvdude]

FLA battery bank consists of 12 Rolls 4KS 21P 1148Ah = 55104 kWh
I had hoped these would be sufficient for large loads, but possibly not?

 

[Solar Guppy]

Those are big batteries, so the next thing is what is your wiring size? I would expect at a minimum 4/0 to minimize voltage drop and the other things to look at is state of charge and when is the last time you checked the specific gravity and water levels of the battery cells?

 

[pvdude]

The batteries came with 4/0 cables, which match the Schneider cables, so good there.
Schneider shunt is 500A.
Batteries recently watered, I'll check the SG.
Feb-7 2024 SG is 1.265, which is 100% charged:

 

[sancsam]

@pvdude Since you have the battery monitor you could setup the XW to control based on SOC then lower the LBCO voltage so that you dont get that warning and use the LBCO on % to stop inverting a your desired battery %.

 

[hwy17]

How long are the inverter to battery wires?

 

[pvdude]

I asked Rolls tech support about the LBCO, after reading this tech note:

Low Voltage Disconnect (LVD OR LVCO)

Many charging systems offer the ability to program a Low Voltage Disconnect (LVD) or Cut Off (LVCO) which triggers an alternate power source (often a generator) to turn on and begin charging the battery bank. When the programmed low voltage sett...

support.rollsbattery.com

Changed the setting from 46 to 45, (1.875 VPC) works better now.

Rolls explained that while 45vdc is a dead battery, (static, no load)
45vdc under load is OK, as the voltage bounces back quickly after the load is removed.

Rolls also told me to avoid the charts/graphs/readings showing SOC as a function of voltage,
only SG matters, according to them.

 

[pvdude]

How long are the inverter to battery wires?

Not sure, whatever Schneider provided w/ the PDP, looks like about 3'?

 

[hwy17]

Not sure, whatever Schneider provided w/ the PDP, looks like about 3'?

Oh I didn't notice the schneider boxes, thought those batteries were in another room or something.