I recently purchased a Goal Zero Yeti 400 (AGM) and had some success and failure with it on the trail.
I did some tests at home before my trip:
1) Charge the Yeti with the supplied AC transformer to 100% per the instructions.
2) Plug my Engel 45 quart fridge using the 12 volt female cigarette lighter port on the Yeti.
3) Press the 12v output button on the Yeti to activate that port.
4) Remove AC input power to the Yeti.
I did this before I went to bed to simulate what I'll be using it for on my trip....charging it while I'm driving via my vehicle's 12volt system or with the Boulder 100 briefcase at camp sites while the sun is out.
When I woke up the next day the Yeti had turned off the 12volt port for some reason and the fridge was not powered and the battery was at 100% capacity. I pressed the 12volt output button on the Yeti to re-activate it and my fridge compressor started humming. I'd walk away and come back and the output would be off again.
I called Goal Zero support and they asked me to open the case and disconnect the battery leads and reconnect them to basically reset the electronics in the controller. I did this and still experienced the same problem. Goal Zero quickly shipped me another unit, with their 12 volt output to female cigarette lighter adapter (as another way to eliminate the mechanical connection as the source of the problem) and sent me a shipping label to return my original unit.
I had one more night to test after the new Yeti arrived and it powered my fridge all night. I packed the land cruiser so that the Yeti was strapped down so my kids could turn around and make sure the output button stayed green. While we were on the road the output stopped repeatedly requiring vigilance to re-activate it. This pattern continued through the entire trip with all of us having to constantly monitor and press the button while driving, at camp on solar, or at night with just the battery powering the fridge.
After a long call with Goal Zero's excellent support staff today it may be that something about how my fridge draws power is running afoul of the safety logic on the controller. They've never seen this behavior before and were ready to ship me another unit which I didn't feel would solve the problem. Instead, they are going to send me the connectors to connect directly to the battery's power poles and use their female 12volt output adapter. This will bypass all of the logic on the controller and while I won't be able to see the output on the LCD display it will hopefully eliminate the shut-off problem.
I'll report back once I've tested this new setup.
I am very pleased with the Boulder 100 briefcase and Yeti 400 combo in terms of it's ability to keep the battery at 100% during sunlight hours and to run my fridge all night. I'd wake up with an icy fridge and 40%-80% battery charge (when the output worked).