When it comes to choosing your power supply for your van its important to think about the power you intend to use as its maximum output . That’s  how much you are going to run , Like fridge , Lights , Heater , USB sockets for charging phones , 240v sockets if your using an inverter . Then decide on how often you intend on using the van for .  We use lithium also known as Lifepo 4 due to the usable power output . For instance a 200ah gel battery will give you 100ah of usable power as you can only drain the battery down to 50% and the lithium battery would give you 180ah of usable power as you can drain the battery down to 20% .

We run a Roamer 230ah lifepo4 with 200w solar power and in summer we never need to hook up to 240 power even on a month long road trip . We do have a victron dc/dc charger so the battery charges when driving but the lithium battery just provides so much more power .

The downside to lithium is its double the price as gel but with roamer you get ten year warranty  and that’s double what you will get with gel plus it gives nearly double the power from the same size battery so in my opinion it’s worth paying the extra money for peace of mind that your not going to end up in the dark on your adventures !