Your electrical system determines how long you can camp off-grid. A basic setup with a single battery and no solar lasts 1–2 nights. A well-designed lithium + solar system can keep you off-grid indefinitely. Here's how to size your system based on how you actually camp.
Electrical System Components
Every truck camper electrical system has four parts: power generation (solar, alternator, shore power), storage (batteries), distribution (wiring, fuse panel), and conversion (inverter for AC appliances).
Battery Types Compared
| Type | Usable Capacity | Weight (100Ah) | Cycle Life | Cost (100Ah) |
|---|---|---|---|---|
| Lead-Acid (Flooded) | 50% (50Ah usable) | 60–70 lbs | 200–400 cycles | $100–$200 |
| AGM | 50% (50Ah usable) | 60–70 lbs | 400–800 cycles | $200–$350 |
| Lithium (LiFePO4) | 80–100% (80–100Ah usable) | 25–30 lbs | 3,000–5,000 cycles | $600–$1,200 |
The math on lithium: A single 100Ah lithium battery provides the same usable power as two 100Ah AGM batteries — at half the weight and 3–5x the lifespan. Despite higher upfront cost, lithium is cheaper per cycle over its lifetime.
Solar Panel Sizing
The right amount of solar depends on your battery capacity and daily power consumption:
| System Size | Solar Watts | Battery (Lithium) | Powers | Best For |
|---|---|---|---|---|
| Basic | 100W | 100Ah | Lights, phone charging, fan, water pump | Weekend trips |
| Standard | 200W | 200Ah | Above + 12V fridge, laptop charging | Extended boondocking |
| Robust | 300–400W | 300–400Ah | Above + inverter loads, coffee maker, blender | Full-time / work from road |
| Maximum | 500W+ | 400–600Ah | Above + AC, microwave, induction cooktop | Residential comfort off-grid |
Daily Power Consumption Guide
To size your system, add up the watt-hours (Wh) of everything you use daily:
| Appliance | Watts | Hrs/Day | Daily Wh |
|---|---|---|---|
| LED lights (all) | 10W | 5 | 50 Wh |
| 12V compressor fridge | 40W | 12 | 480 Wh |
| Vent fan | 15W | 8 | 120 Wh |
| Phone charging (×2) | 15W | 3 | 45 Wh |
| Laptop | 60W | 4 | 240 Wh |
| Water pump | 60W | 0.5 | 30 Wh |
| Furnace fan | 30W | 6 | 180 Wh |
| Coffee maker (via inverter) | 900W | 0.1 | 90 Wh |
| Total | ~1,235 Wh | ||
At 1,235 Wh/day, you need about 100Ah of usable lithium capacity (at 12V) per day. With 200W of solar producing ~800 Wh/day (4 peak sun hours), you'd need to supplement with driving (alternator charging) or start with fuller batteries. Bumping to 300W solar gets you to energy independence in most sunny locations.
Shore Power: 30 Amp vs. 50 Amp
When plugged into campground power:
- 30 amp (most truck campers): Provides 3,600 watts. Enough for all camper systems simultaneously including AC.
- 50 amp (large hard-sides only): Provides 12,000 watts. Only needed if you have two AC units or a residential fridge plus AC.
Inverter Sizing
An inverter converts 12V DC battery power to 120V AC for household appliances. Size it to your largest AC load:
- No inverter: If you only use 12V/USB devices
- 300–500W: Laptop charging, small electronics
- 1,000–1,500W: Coffee maker, blender, hair dryer (one at a time)
- 2,000–3,000W: Microwave, induction cooktop, AC unit
Watch out: Large inverters draw significant power. A 1,500W inverter running a coffee maker for 10 minutes pulls about 20Ah from a 12V battery. Make sure your battery bank can handle the draw rate (check the C-rating or max discharge rate).
Alternator Charging
Your truck's alternator charges the camper battery while driving. This is often the most underrated charging source:
- A basic isolator provides 20–40 amps while driving
- A DC-DC charger (Renogy, Victron) provides 30–60 amps with proper charging profiles for lithium
- One hour of driving can add 30–60Ah to your camper batteries — equivalent to 2–4 hours of solar