AC cuts out at 90%of batteries

[Tony Horne]

I am new to this so apologies if this is really simple.
I have 1490 total watts of solar, four 300Ah Relion 8D lithium batteries for total of 1200Ah, a Victron Multiplus 3000 inverter/charger. I recently bought the boat. Initially the power was constant evenwhen the batteries drop to 80%, but in the last week if the batteries drop to below 90% the AC cuts out. I have not changed any settings. What should I be checking and look at?

[S/V Illusion]

What are you referring to as “AC” cutting out - the air conditioner or the alternating current?

If the latter, first thing to do is measure current draw.

[Tony Horne]

By AC mean 110v.

[S/V Illusion]

Ok, that’s the first part of the puzzle. I’m assuming what you refer to when you say cuts out is the power output from the inverter - is that correct?

[ItDepends]

First thing, you have to understand that the battery meter that is reporting the state of charge (SOC) doesn't really know that number. All it does is measure what goes in and subtracts what goes out. If the batteries are not of the same capacity as the meter was told (i.e., they are old and failing) the actual SOC will have very little to do with the reported value.

Now... what cuts off the inverter making AC current is low battery voltage. Do you know what the voltage is when the AC is shut off?

It is POSSIBLE that value is adjusted too high in the inverter settings, but it is far more likely that your batteries are actually nearly dead. What the meter thinks is 90% full is actually much, much, much lower.

[smac999]

What is the battery voltage Reading when they are at 90 or 80%.


When was the last time you plugged into a dock and charged With shore?

If not for a while it’s possible the meter is un synced.

Those batteries should be able to power the inverter down to like 20%