Truck campers are unique in the RV world — a self-contained unit that slides into the bed of a pickup truck. The electrical system must work both connected to the truck (via 7-pin connector) and as a standalone unit on shore power.
Our free electrical calculator takes the appliances you plan to run and sizes the whole system around them, with a wiring diagram and parts list at the end.
How truck camper electrical works
From the truck: The 7-pin trailer connector typically includes a 12V charging wire (pin 4, blue or auxiliary) that connects the truck's charging system to the camper's house battery. Trucks with a 7-pin connector and "trailer charging" option run a wire from the fuse box to pin 4.
Shore power: Most slide-in campers include a 30A shore power inlet. When plugged in, a converter/charger charges the house battery and powers 120V loads.
Internal wiring: Factory truck campers wire 12V loads (lighting, fridge, water pump, fans) from the house battery, with a converter to power 120V outlets from shore or a built-in inverter.
Upgrading a truck camper electrical system
Replacing AGM with LiFePO4:
Most factory truck campers use 1–2 Group 27 or 31 AGM batteries. Replacing with LiFePO4 of the same group size gains 2× the usable capacity at the same or lower weight (LiFePO4 is lighter than AGM). A drop-in 100Ah LiFePO4 in a Group 31 form factor is often a direct replacement.
Adding solar:
Truck campers have limited roof space but even 100–200W solar meaningfully extends off-grid time. Use lightweight flexible panels or low-profile rigid panels with minimal roof penetration. Install an MPPT charge controller — most factory converters don't include one.
DC-DC charger from truck:
On 2019+ trucks (Ford F-150 EcoBoost, Ram 1500 eTorque, GM trucks with variable alternators), the 7-pin charging pin voltage fluctuates with the smart alternator. Install a 20–30A DC-DC charger between the 7-pin feed and the house battery for proper LiFePO4 charging.
Common upgrade path
- Replace factory AGM with 100Ah LiFePO4 (same group size, drop-in)
- Add 200W flexible solar panel on roof
- Install 20A MPPT charge controller
- Install 20A DC-DC charger for truck alternator feed
- Upgrade factory converter to a Victron IP22 or similar LiFePO4-compatible charger for shore power
Cost: $800–$1,500 depending on brand choices. Result: off-grid capability that far exceeds a factory truck camper.
US equipment options
Compare the storage and charging choices separately
A house battery and an alternator charger address different parts of the upgrade. Verify truck-to-camper wiring, the charging source and the exact mounting space before choosing either.
House battery
Epoch 12V 105Ah Essential Series LiFePO4 Battery (1.34kWh)
A compact-capacity option to compare for a modest daily energy budget.
Check before choosing: Physical fit, usable energy, discharge current and the exact cold-charge/heating specification.
Alternator charging
Victron Orion XS 12/12-50A DC-DC Battery Charger
A 12V-to-12V charging option for a compatible vehicle and house-battery installation.
Check before choosing: Alternator headroom, cable run, battery charge acceptance and the required controls/protection.
These links open our US shop. Check the exact configuration, current price and availability there; affiliate products are purchased from the named supplier. We may earn a commission from qualifying purchases.
Electrical connections truck-to-camper
7-pin connector: Pin assignments for SAE J560:
- Pin 1: Ground
- Pin 2: Running lights
- Pin 3: Left turn/brake
- Pin 4: Battery/auxiliary charging
- Pin 5: Right turn/brake
- Pin 6: Tail lights
- Pin 7: Reverse
The aux charging pin (4) is what charges the camper battery while driving. Maximum current on this circuit is typically 20–30A fused.
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Jack Kennedy is a self-builder who has built two vans. He created Roam Wired to simplify conversion planning and share free tools, supported by affiliate links.
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