Eco Solar Refrigerator advice

HI ula,

Welcome! Interesting. From the link you sent, based on the specs, it appears the unit could draw up to 96W maximum. At 12V this is 8amps which for 6' of 12AWG will likely have ~1.4% voltage drop (11.8332V at the fridge assuming 12V at the battery and no other resistance in the circuit).

And your battery is:

Presumably nominal voltage is ~13V?

The minimum fridge operating voltage is (10.4V):
Input Voltage Range for 12v / 24v System (V) 10.4 - 16.8 / 21.3 - 31.5 DC

So, this leaves us with three questions:

1) Is the fridge compressor running all the time but not getting cold?
1A) fridge empty -- very hard to cool lots of dead air. Especially with a tiny energy efficient compressor. Add pre-chilled food / cardboard to take up space.
1B) Faulty compressor refrigerant
1C) Verify that the compressor is running 100% duty, measure the voltage and current at the fridge while it's running to be sure voltage is high enough, and amps is as expected. The fridge might be so quiet you cannot hear the compressor run

2) Is the fridge compressor cutting out b/c the voltage drops too low? Or cutting out for some other reason (low refrigerant, overheating, tripping fuse/breaker, etc.)

3) Given your small 90AH battery, given a DOD of 50-70%, you'll only be able to run the fridge for approx 3 to 5 hours (at 8amps continuous) AT MOST until your battery requires charging. Depending on the voltage curve of your battery, the compressor may cutoff before that. The 90AH rating on this battery is over 20 hours, so that's ~4.5amps per hour. Since you may be drawing more current than this, your observed capacity will be less. You'll be killing your tiny battery in short order with this type of usage. generally for FLA batteries you only a DOD of 30% to at most 50%.

So it could be that your fridge is running, and starting to get cold, but it drains your battery dead and your one solar panel cannot keep up.

There is a certain ratio of Solar Watts to battery Amp hours and battery voltage that folks here on the board recommend. Additionally folks generally advise agent "commodity" car batteries in favor of 2V or 6V batteries in series from quality companies like Trojan, etc. I don't know much about such recommendations, but I'm sure some other folks here will chime in.

-Jonathan