Not enough AH?

Hello. Would appreciate some input as I am new to solar power set ups. I have an off grid cabin which has power supplied from:

4x100w renogy panels on roof facing south at 10-15 degrees (seems to get a ton of sunlight)

Three 12v 100ah deep cycle renogy batteries

Renogy Adventurer 30amp CC

Windynation 1500watt pure sine inverter

My problem is as follows:

I have a small Whynter off grid fridge using 80 watts when running and yesterday it was hot and I loaded it up and didn’t think it would be a problem with my set up. When I came back near the end of the day the voltage of my batteries was reading at 12.2 Which as I understand means it could be as low as forty percent charge.

If my math is correct (80watts x 8 hours of use = 640 watts/12 volts = 53ah) shouldn’t it have lasted a lot longer?

Or am I all messed up because the inverter is 115v which would reduce the ah to only 5.5?

The fridge runs off of 12v as well. Should I connect it directly to the batteries?

Thank you for your help.

Cheers

Thanks tattoo.

Although I’m still a little confused. The fridge has two power input abilities; 120v AC and 12v DC. So if DC appliances are lame should I run it from the inverter? Though you stated I should connect directly to the battery?

I use the inverter for charging all my devices (computer, phone, etc) and the occasional TV watching and can easily connect the fridge to the inverter as it is now.

The 12.2v reading was in the late evening. During the day while running the fridge it seems to stick around 12.5-6. CC is putting out about 19 amps in full daylight.

Was thinking of adding another 100ah battery and 100watt panel as I’ve only set this up a month ago. (I believe the CC can easily handle 5x100w panels?)

Forgive my ignorance and I truly appreciate the help.

By all means get another panel. 12v to the battery and 110v to the inverter. Try them both and see if one pulls the batteries down less than the other...

Thank you! That helps a lot. Got some experimenting to do.

Cheers