Where to Mount Your RV or Van House Battery
Battery placement affects cable length (and therefore cost and voltage drop), weight distribution, accessibility, and ease of build. Here are the most common locations and how to choose.
Location options
Behind the driver's seat
Pros: Close to the firewall, minimizing the length of the DC-DC charger wire run from the engine bay. Short cable to the main fuse and bus bar. Good structural mounting point (floor or bulkhead).
Cons: Reduces the usable space behind the driver's seat, which many van builders want for a garage or seat.
Best for: Simple builds where minimizing cable length and cost matters. Single battery or small bank.
Under a bed platform
Pros: Uses otherwise-dead space under the sleeping platform. Keeps the battery out of the way. Weight is low and toward the center of the van — good for handling.
Cons: May increase cable length to the DC-DC charger input. Harder to access if the bed platform isn't designed for easy battery removal.
Best for: Full builds with a fixed bed where the underbed space is purpose-designed around the battery.
Dedicated floor box (cargo area center)
Pros: Custom-built battery box bolted to the van floor. Allows the battery to be easily removed. Can be made weatherproof and secure.
Cons: Takes floor space; custom build required.
Best for: Professional builds or anyone who wants a clean, purpose-built installation.
External compartment (RVs)
Class B and C RVs often have external battery compartments (under-floor storage accessible from outside). Good ventilation, keeps battery out of the living space, but increases cable runs to interior loads.
Cable length considerations
The DC cable run from battery to main bus bar should be as short as practical — under 3 feet is ideal. Every extra foot of 2/0 AWG cable adds ~$3–$5 and a small amount of voltage drop. More importantly, the main fuse must be within 18 inches of the battery positive terminal regardless of where the battery is.
Longer cable runs require heavier gauge wire to maintain the same resistance. A 6-foot run from battery to inverter requires heavier cable than a 2-foot run.
Mounting requirements
Security: A 100Ah LiFePO4 battery weighs 26–29 lbs. In a crash or sudden stop, an unsecured battery becomes a projectile. Mount with:
- Battery hold-down bracket or strap
- Rigid battery box with lid and latch
- Bolts through the van floor or frame rail (not just into the floor sheet metal)
Accessibility: You'll need to inspect terminals, check for corrosion, and potentially remove the battery. Design the installation so you can access the battery without disassembling the entire van.
LiFePO4 ventilation: Not required for safety (no hydrogen gas) but recommended for thermal management in hot climates. Don't seal a battery in a hot, unventilated metal box.
AGM/lead-acid: Must be vented to outside air — these batteries off-gas hydrogen during charging. Never install in a sealed compartment.