I thought I would add some thoughts on our Yeti 400. We did a two week long trip recently, spending 6 days on the road camping.
The Yeti is mounted under a passenger seat, and I have the car charger routed to it so its continuously charging. I can confirm it only charges when it sees the additional voltage from the alternator, and stops charging when you stop the motor. This is a fantastic feature. We kept the unit in the car during freezing temps and I did't notice any drop in performance/charge.
We used it for charging all our USB devices, charge the GZ lantern, as well as power GZ lighting at camp. We also used the AC outlet to power our blow up mattress. For the most part we left it in the vehicle, except at camp to power the lights and be a charge station. Doing these things it worked fantastically. I love that it's semi-permanently mounted, so we can move it around and use it as needed. The flexibility is nice.
The display works great. It's easy to read at a glance. I would love an iOS app that can display the stats over Bluetooth so I can check on it while having it tucked away.
i don't have many gripes, only ideas to improve the device. I have Anderson power pole plugs already wired, I would really like to use that type of connector vs the proprietary charge connector. I would like a charge port on the back as well. I would like to see GZ move to LifPO batteries, this thing is not light. I would also like to see it be able to do 20A draw. We have a coffee maker I want to use the GZ for but clearly the warm up of the hot surface trips the breaker. It needs a tie down loop or two on it, I want to secure it better and more safely in case of vehicle crash.
One tip is to get a USB multi cable with every modern connector on it, because you never know what device you will need to charge. Keep that with the 400. Also plug a cigarette lighter to USB adapter into it to double the USB ports.
I am planning to create an Anderson to battery clip cable so if I ever need a jump for the vehicle in an emergency I can use the 400. I realize that's not approved, but it's for emergency. If chaining would allow me 20A I would do it in a heartbeat. I am thinking about adding solar for trips where we sit parked longer.
Over all a really nice unit. Would buy again, I may buy another. I am emailing GZ my suggestions.