Energy use is power multiplied by time: watts × hours = watt-hours. Add up every device, allow for conversion losses and a reserve, then compare that requirement with usable battery capacity and your actual charging options. This planner estimates one load at a time.
What will one device use?
Enter the device’s actual running draw and the hours it runs. For cycling appliances, use measured average draw or actual running time. The result is an energy estimate before inverter losses or a reserve, not a battery recommendation.
Watts × running hours. Before conversion losses and reserve. For cycling loads, enter actual run time or average measured draw. Not a battery-size or electrical-system recommendation.
Build a daily energy list
The example below is arithmetic, not a measured RV test. Replace every number with your own device measurements. Battery watt-hours and inverter watts describe different limits: stored energy determines duration; output rating limits what can run at once.
| Example load | Power × time | Energy |
|---|---|---|
| LED lighting | 10 W × 4 h | 40 Wh |
| Laptop | 60 W × 2 h | 120 Wh |
| Vent fan | 20 W × 6 h | 120 Wh |
| Illustrative total | Before losses / reserve | 280 Wh |
LAST UPDATED: 2026-09-14
Count the ways you can recharge
List shore power, a compatible vehicle-charging setup, solar, or an allowed generator as separate options. A panel’s nameplate rating is not its all-day production. Shade, angle, temperature, weather, and charge-controller limits affect the result.
For wiring changes or roof-mounted systems, use the RV and component manuals and a qualified installer. Never feed an RV or building circuit through an improvised backfeed connection.
YOUR NEXT USEFUL STEP