Tools → RV Electrical Load Calculator

RV Electrical Load Calculator

Free 12V power calculator for RV, camper and van. Calculate daily amp-hour usage, battery runtime and solar panel sizing. Plan your boondocking power budget.

For educational purposes only. Always verify specifications with manufacturers and consult qualified RV technicians for safety-critical decisions. See our Terms of Service.
Your Devices

Quick add common devices:

Device Amps Hours/Day Ah/Day
Your Battery Bank
Ah
Add up all your batteries. Two 100Ah = 200Ah.
Lithium can be discharged deeper without damage.
Daily Power Budget
Daily Usage
0 Ah
Usable Capacity
80 Ah
Days on Battery
--
Solar Needed
-- W
Add devices above to calculate your power budget

Understanding 12V Power

Amp-Hours (Ah) Explained

Amp-hours measure battery capacity and consumption. If a device draws 5 amps for 2 hours, it uses 10 amp-hours (5A x 2h = 10Ah).

Battery Depth of Discharge

Lead-Acid/AGM: Should only be discharged to 50% to preserve lifespan. A "100Ah" battery really only gives you 50Ah of usable power.

Lithium (LiFePO4): Can safely discharge to 80-90%. More expensive upfront but more usable capacity and longer lifespan.

Solar Panel Sizing

The "Solar Needed" estimate assumes 4-5 sun-hours per day (average US conditions). In winter or cloudy areas, add 25-50% more panels.

Tips for Reducing Power Use

  • Switch all lights to LED - uses 1/10th the power of incandescent
  • Use propane for heating/cooking instead of electric
  • 12V compressor fridges use 1/3 the power of absorption fridges
  • Turn off inverter when not in use - standby draw adds up

Can You Run A/C on Battery?

Technically yes, but it's impractical for most setups. A roof A/C draws ~13A at 120V, which translates to ~125A at 12V through an inverter. One hour of A/C uses 125Ah - more than most battery banks hold! You'd need a massive lithium bank (400Ah+), a 2000W+ inverter, and serious solar. Most RVers run A/C only on shore power or generator.