Where to Put Your Battery in a Van or RV: Location and Safety
Where you put your battery affects cable length, safety, weight distribution, and how easy the system is to maintain. Here are the best options.
What makes a good battery location
Short main cable run: Every foot of 2/0 AWG cable between battery and bus bar costs money and adds resistance. Ideally 18–36 inches; 48–60 inches is acceptable; longer than 6 feet typically requires upgrading to 4/0 AWG.
Secure mounting: The battery must be restrained against movement in a crash and normal driving. A 100Ah LiFePO4 weighs 25–30 lbs — unrestrained, it becomes a projectile in a collision.
Temperature stability: Avoid locations that see extreme heat (near engine, in direct sun) or extreme cold (exposed under-floor areas in northern climates). LiFePO4 operates from −4°F to 140°F but charges safely only above 32°F.
Accessibility: You should be able to reach the battery terminals, check connections, and access the BMS connector without disassembling major build components.
Weight distribution: Battery weight is significant for handling. Locate it over or near the van's center of gravity, low in the vehicle, and balanced side-to-side.
Best battery locations for van builds
Under-bed platform
The most common location in full van conversions. A battery box or enclosure built under the fixed bed platform, typically positioned over the rear axle or forward of it.
Pros: Low center of gravity, good weight distribution, short cable run if electrical panel is in an adjacent cabinet, out of the way of living space.
Cons: May reduce bed storage underneath; access requires opening a hatch or panel in the bed base.
Setup: Build a reinforced section in the bed base with a lift-out or hinged panel for access. Strap or bracket the battery to the floor structure.
Rear cabinet / dedicated battery cabinet
A floor-level cabinet behind the passenger seat or driver's seat, with the electrical panel immediately above or adjacent.
Pros: Easy access, short cable runs to the electrical panel, visible from the door.
Cons: Takes up prime cabinet real estate; battery in the cargo area can be a theft risk if van is opened.
Floor-mount battery box
A dedicated secured battery box (steel or quality plastic) mounted directly to the van floor with through-bolts.
Pros: Low center of gravity, simple mounting, works for builds that don't have a full interior conversion.
Cons: Takes floor space, may reduce headroom in low areas.
ProMaster/Transit under-floor storage (specific models)
Some ProMaster and Transit builds use the built-in subfloor or floor rail system to create a battery location under the main floor level. This requires careful waterproofing and thermal management but achieves very low CG placement.
Locations to avoid
Engine compartment
High heat, vibration, and exposure to engine chemicals are all hard on battery packs. Engine compartments also have limited space for additional wiring runs.
Under-van external mounting
Exposed to weather extremes, road salt, gravel impact, and theft. Some overlanding builds do this with heavy steel boxes — requires careful waterproofing and security.
In the cab (front seats area)
Safety regulations in most US states require battery enclosures to prevent gas exposure to occupants. While LiFePO4 doesn't produce significant gas, regulatory compliance and safety margin argue against cab installations.
Securing the battery
Hold-down straps: Metal bracket straps that cross over the top of the battery and bolt to the floor — simple and effective for single-battery installs.
Angle brackets: L-brackets screwed to the floor that the battery rests against — prevents sliding without full restraint.
Battery box with lid: A purpose-built or DIY box with a securing lid. The box itself is bolted to the floor; the battery is held by the box's walls.
For LiFePO4, any of these work — the key is that the battery cannot slide, tip, or eject in a crash or sudden stop.
Thermal management considerations
Cold winters: If your battery is in a well-insulated van and you don't charge it below 32°F, standard battery placement is fine. For northern climates: some builders install self-heating LiFePO4 (the battery has an internal heater that activates below freezing before charging).
Hot summers: Battery temperature above 140°F (60°C) causes accelerated degradation. Avoid placing the battery directly below a south-facing window or in a location that gets full afternoon sun. Ventilate the battery compartment in summer for temperature management.