I'm running my van from a GZ Yeti 1500X. That powers fans, fridge (Norcold NR75), lights, a couple USB ports I built in. It's good for about 2 days of full autonomy without any charging. If I were doing it again I might consider the 3000X.
A few pointers:
-Make sure whatever you get has a high power output. The 1500X has a 12V/30A Anderson/Powerpole port. I made a custom connector to attach this to the bus bar of a Blue Sea fusebox, which distributes to the rest of the van. This is actually really easy, just get some 10 AWG wire, a couple ring connectors, and an
Anderson plug kit.
-As Broken and Costal mentions, the Yeti Link doesn't work with the Transit's smart alternator. He and I are probably working on the same hack to fix this; you can read about the tribulations
here. If you want to charge from the engine while driving, you can use the GZ car charger, but it's slow (120 watt max). Further info once I get some parts in to address this.
-Set up a shore power plug to keep the GZ charged. I installed mine under the left rear corner of the van, easy to plug in when van is in my driveway.
-If you're running a fridge, it's a good idea to get an AC/DC model. The Norcold I have will default to AC power if available, if not it's DC. I plugged a splitter into my shore power line and connected that to the fridge. This way when it's plugged in, the fridge (by far your biggest load on the battery) is running off shore power, not the battery; this saves you charge cycles when the van is plugged in.
-I initially thought I'd just use the USB and AC outputs on the battery, but this is kind of a PITA. You really want the battery mounted somewhere secure and low to the ground, as it's very heavy and you wouldn't want it flying around in an accident. I ended up wiring some USB ports in various places around the van, and ran an extension cord from the AC output of the battery to a permanently installed AC plug at counter level. Avoid combo AC/USB plugs, as they have substantial parasitic draw.
