Battery time powering inverter

[Bobgaudette]

I have a 2016 Windsport 34j and curious how long the two house batteries should be able to power the inverter running just the two refrigerators before the inverter shuts off (errors) because batteries are too low. Mine is very short, like under an hour. Batteries are new and deep cycle.

[DavidEM]

Depending on size, type and whether they have icemakers or not, a pair of refrigerators can easily draw 80 amps DC from the inverter when their compressors are running. After an hour of this load, even if it is cycling at 30%, the battery voltage can easily be down to the point that it trips the inverters.

You need a a big bank of lithium batteries to run two refrigerators for long.

David

[16ACE27]

Well there's deep cycle:


and then there's Deep Cycle:


The latter having twice the capacity of the former.

But regardless, only 1 hour on two new batteries seems awfully low. I would expect at least 6 to 8 hours.

The Whirlpool WRS312SNHM Refrigerator use 528 KWH per year which averages to 60 watts average running or 5 DC amps.
The small outdoor fridge uses less than half that, so we'll call it 3 DC amps.
Round up for inverter inefficiency and call the average DC load for the 2 fridges 10 amps.

So if you've got two 100 AH batteries you should be able to go 10 hours before reaching the 50% threshold in a perfect world. Now those are EPA KWH numbers, the same people that put MPG numbers on new cars; so take them with a grain of salt. But even so, 5 hours wouldn't be unreasonable.

Now if the fridges are running continuously because you just turned them on and they aren't down to static temperatures then this time would be much less.

[Chateau_Nomad]

Our class C came with that "Everstart" which is actually a hybrid. It was the first thing to go... sold it for $10.

Also - remember running an inverter is less efficient than direct 12 volt. There's a conversion from DC to AC which, although convenient and sometimes unavoidable, wastes some of your battery reserve.

Ideally for us, I'd like to eventually switch to a 12volt/propane fridge.