Solar, lithium batteries and motorhome electrics
The questions Steve gets asked more than any others. How much solar you need, why we carry a big battery bank, and what is actually in our Victron system.
How much solar do I need on a motorhome?
Work backwards from how you camp, not from what fits on the roof. If you are mostly on hook-up you need very little. If you wild camp for days at a time, add up what you run in a day, decide how many days you want between charges, and size the battery bank from that. Then a decent rule of thumb is solar of roughly 40–50 percent of your battery capacity in watts so the bank recharges in sensible time. For scale, our old Kon-Tiki carried 950 watts of solar with a big lithium bank behind it, and the Dethleffs runs a bigger system again because we camp off grid so much.
Why do you have so much battery capacity?
Because the way we like to camp depends on it. Steve prefers wild camping and aires to fixed campsites, and a big lithium bank is what makes that genuinely comfortable rather than an exercise in rationing: the fridge, the heating controls, everyone's devices, camera batteries for filming, and cooking appliances off the inverter. Capacity is freedom from the hook-up post, and once you have toured that way it is very hard to go back.
Can I fit a lithium battery myself?
A competent DIYer can, and plenty do, but go in with respect for it. It is not just swapping a box: charge profiles need setting correctly, the alternator charging needs a proper DC to DC charger so you do not cook the alternator, cable sizing and fusing matter enormously at these currents, and it all has to be safe in a moving vehicle your family sleeps in. We used professionals for our installs and film the process rather than pretending we did it ourselves. If in doubt, pay someone qualified and spend your bravery elsewhere.
What is actually in your Victron system?
The heart of ours is the Victron ecosystem: a Cerbo GX as the brain with the touchscreen giving live numbers on everything, MPPT controllers for the solar, an Orion XS DC to DC charger doing the alternator charging, and Fogstar Drift Pro lithium batteries providing the bank. We will not quote you an installed price because it depends entirely on your van and the size of system, and second hand numbers age badly. Size the system to how you camp and get a current quote.
Where should the batteries go in the van?
As close to the heavy loads as the layout allows, because short, fat cables lose less than long runs, and voltage drop at inverter currents is real money wasted. The garage is tempting for access but think about the cable run back to the electrical centre before committing. Keep the weight low and think about your axle loads while you are at it, since a big lithium bank is a payload item like everything else.