RV and van
House power for an RV or van build
The short answer
In a van the battery is not a component, it is the house. Everything else in the electrical system exists to fill it or empty it. Get the capacity and the charging right and the rest of the build is straightforward. Get either wrong and you will be chasing the fault for a year.
What size lithium house bank does a van build need?
Work it out from the loads, not from what somebody else fitted.
Add up what actually runs: the fridge, which is on all day, then lights, fans, water pump, charging for devices, and anything with a motor in it. Multiply by the hours each one runs. That gives the amp hours you use in a day, and the bank has to cover a realistic day with margin for the grey week when solar gives you almost nothing.
Because lithium gives you the whole capacity rather than half, the number you need is smaller than the lead acid equivalent people usually quote. Lead acid should not be taken past 50 percent if you want it to last. Lithium goes to 100 percent and holds voltage the whole way, so the fridge behaves the same at the bottom of the bank as at the top.
Why does weight matter so much in a van?
Because payload is the constraint nobody plans for until the build is finished.
A van has a gross weight limit, and by the time you have added insulation, cabinetry, water, and a person or two, a lead acid house bank is a serious share of what is left. LBP batteries average about 70 percent lighter than the lead acid they replace, which is weight you get back for water, gear or a second passenger.
How do I charge a lithium house bank?
From three directions, usually all wired into the same bank: shore power, solar and the engine.
Each one has a condition attached. Shore power means a lithium charger or an inverter charger set to a lithium profile. Solar means a charge controller that is lithium compatible, which is not all of them, and a controller that is not will either undercharge the bank or refuse to work with it properly. The alternator side needs its own control so the engine is not asked to do something it was not designed for.
The profile to aim for on an inverter charger is bulk at 14.4V, absorb at 14.6V and float at 13.6V. Nothing should go above 15V. If your charger has no custom setting, pick the closest profile that stays under that ceiling.
Is my solar charge controller compatible with lithium?
In most cases an LBP battery works with a solar charger, but the controller has to support lithium specifically.
This is worth checking before anything is bought rather than after, because the controller is usually the cheapest part of the system to change and the most annoying to discover late. If the controller has a lithium or LiFePO4 profile, you are fine. If it only offers lead acid profiles, it is the wrong controller for the bank.
What goes wrong in van electrical builds?
Almost always the charging, and almost never the battery.
The pattern repeats: a good bank is fitted, then charged by a controller or a charger that was chosen for a lead acid system. The bank never quite fills, the runtime is short, and the battery gets blamed. The second common one is a bank sized against somebody else’s build rather than against the loads actually in the van, which produces either a bank that runs out on day two or a bank carrying weight for capacity that is never used.
Both are cheap to avoid at the planning stage and expensive to fix once the cabinetry is in.
Can I grow the bank later?
Yes, up to four batteries in parallel.
Parallel adds capacity at the same voltage, which is the usual way a house bank grows. Four in series is also supported, which is how you reach 24V or 48V where a system calls for it. Beyond four in either direction is outside what LBP supports, and an unusual arrangement is worth a conversation before the wiring goes in.
How long will the batteries last in a van?
Between 5 and 15 years, or 2,000 to 5,000 cycles.
Full time living cycles the bank daily and lands at the harder end. Weekend use lands at the easier end. Either way it is a component you fit once and live with, rather than a consumable you replace every few seasons the way lead acid tends to be.
Where can the batteries be mounted?
Anywhere dry, ventilated and secure, and not anywhere water collects.
LBP batteries are IP65, which covers spray and rain but not immersion. Submerging one can fail the silicone seal and voids the warranty. In a van that mostly means keeping the bank out of a wet locker and securing it properly, because a heavy object that can move in a crash is a safety problem before it is an electrical one.
Can I check the bank from my phone?
On Bluetooth models, through the Battery Genie app on iOS and Android.
For full time living this is the difference between knowing where you stand and guessing, and it matters most on the days when solar is doing very little.
Where next?
- The lithium battery guide for BMS, series limits and charging.
- Golf cart conversions if that is the other project.
- LBP compared with Dakota Lithium for choosing
between brands.
If the build does not fit standard sizes, Lithium Battery Power builds custom packs from Clearwater, Florida, and that is worth a call before the layout is fixed.
Talk to someone who builds these
LBP builds custom packs as well as shipping standard sizes, and the team will size a bank to the boat, the cart or the rig before anything is bought.
Keep reading
- Choosing a lithium battery, without guessingHow to pick a lithium battery by voltage, amp hours and application, what a BMS actually does, how charging differs from lead acid, and where the limits are.
- Sizing a lithium battery for a trolling motorHow to match voltage and amp hours to a 12V, 24V or 36V trolling motor, what decides a full day on the water, and how lithium changes the sizing maths.
- All guidesEvery guide on lithiumbatterypower.com in one place.
Last reviewed Lithium Battery Power