RV Battery Runtime Calculator
Estimate how long your RV battery bank will power your appliances, whether you use lithium, AGM, gel, or flooded lead-acid batteries.
1. Battery Bank Details
2. Appliance Power Usage
Enter the actual running watts and average operating hours per day. Use 0 hours for appliances not in use. AC loads include inverter conversion losses; DC loads do not.
3. Battery Runtime Results
Daily Appliance Energy Breakdown
| Appliance | Energy drawn from battery (Wh/day) |
|---|---|
| Calculate to view breakdown. | |
Estimates assume the same daily use and average solar yield. Real-world battery voltage, capacity, inverter losses, temperature, age and charge-controller behavior can change results.
Free RV Battery Runtime Calculator: How Long Will Your Battery Last?
Planning a boondocking trip or camping without hookups? This free RV battery runtime calculator estimates how long your battery bank can run lights, a refrigerator, fans, electronics and other RV appliances. Enter your battery capacity in amp-hours (Ah), voltage, chemistry and appliance power consumption to estimate runtime in hours or days.
How to Use the RV Battery Runtime Calculator
- Choose your battery chemistry and enter the total battery bank voltage and capacity in amp-hours.
- Enter the current state of charge and your planned maximum depth of discharge. Follow the battery manufacturer's recommended limits.
- Enter inverter efficiency and standby draw if you use AC appliances.
- Adjust each appliance's running watts, hours per day and DC/AC power source.
- Optionally include estimated solar production, then select Calculate Battery Runtime.
RV Battery Runtime Formula
Remaining usable energy (Wh) = Nominal energy × max(0, current state of charge − minimum allowed state of charge) / 100
Runtime (days) = Remaining usable energy ÷ Net battery energy used per day
The minimum allowed state of charge equals 100% minus the selected maximum depth of discharge. For example, with a 50% maximum depth of discharge, the calculator does not count energy below 50% state of charge as usable. AC appliance energy is divided by inverter efficiency to estimate battery draw, and inverter standby energy is added separately.
12V RV Battery Runtime Example
A 12V, 200Ah battery bank stores approximately 2,400Wh nominally. If the bank is fully charged and you plan to use 80% of its capacity, approximately 1,920Wh is available before considering further losses. At a constant battery demand of 400Wh per day, the simple estimate is 4.8 days without solar. Real-world runtime can be shorter, particularly with lead-acid batteries under high loads.
How Long Will a 100Ah or 200Ah RV Battery Last?
| Battery bank | Example usable energy | Runtime at 500Wh/day |
|---|---|---|
| 12V 100Ah LiFePO4 (80% DoD) | 960Wh | 1.9 days |
| 12V 200Ah LiFePO4 (80% DoD) | 1,920Wh | 3.8 days |
| 12V 100Ah lead-acid (50% DoD) | 600Wh | 1.2 days |
| 12V 200Ah lead-acid (50% DoD) | 1,200Wh | 2.4 days |
These are simplified examples based on a nominal 12V bank at 100% charge, without solar or additional losses. Many LiFePO4 batteries have a nominal voltage of 12.8V, so check your actual bank specification.
Factors That Affect RV Battery Life
- Battery chemistry: Lithium iron phosphate (LiFePO4) and lead-acid batteries have different usable-capacity and discharge characteristics.
- Depth of discharge: A larger permitted discharge provides more usable energy but must remain within manufacturer guidance.
- Appliance duty cycle: A refrigerator or water pump usually runs intermittently rather than at its rated watts all day.
- Inverter losses: AC appliances draw additional battery energy because the inverter is not perfectly efficient.
- Weather and battery condition: Cold temperatures, aging and high current loads may reduce available energy.
- Solar charging: Actual solar harvest varies with shading, weather, panel angle and charge-controller losses.
Tips to Make Your RV Battery Last Longer
- Use efficient LED lighting and energy-saving appliances.
- Turn off the inverter when it is not needed, if safe for your equipment.
- Measure real appliance usage with a watt meter or battery monitor.
- Reduce unnecessary electrical loads during overnight camping.
- Check your battery manufacturer's recommended charge and discharge limits.
- Keep solar panels clean and minimize shading where practical.
RV Battery Runtime Calculator FAQs
How do I calculate RV battery runtime?
Multiply battery voltage by amp-hours to find nominal watt-hours, apply the permitted depth of discharge and current state of charge, then divide usable energy by daily battery consumption. Account for inverter losses when powering AC appliances.
How long will a 100Ah lithium battery last in an RV?
At 12V and 80% usable depth of discharge, a fully charged 100Ah battery provides approximately 960Wh in a simplified calculation. At 40W of continuous battery draw, that is about 24 hours. Check your battery's nominal voltage and specifications.
How long will a 200Ah RV battery last?
Runtime depends on voltage, chemistry, state of charge and appliance use. A fully charged 12V 200Ah battery with 80% usable depth of discharge has approximately 1,920Wh available, or about 48 hours at a continuous 40W draw before other losses.
What is the difference between Ah and Wh?
Amp-hours (Ah) measure electrical charge capacity, while watt-hours (Wh) measure energy. For a simplified battery estimate, Wh = Ah × nominal voltage.
What depth of discharge should I use for an RV battery?
It depends on the battery model. The calculator starts at 80% for LiFePO4 and 50% for lead-acid as planning examples. Always follow the manufacturer's recommendations and battery-management-system limits.
Can I calculate runtime for a 24V or 48V RV battery bank?
Yes. Select 24V or 48V, or enter a custom bank voltage, then enter the bank's total amp-hour capacity at that voltage.
Does an inverter drain an RV battery?
Yes. An inverter uses energy to convert DC battery power to AC and may also consume standby power while switched on. The calculator includes both factors.
How much solar power do I need to keep my RV battery charged?
Compare your average daily battery demand in Wh with expected daily solar production. Solar production can be estimated as panel watts × peak sun hours × system efficiency. Weather, shading and battery charging limits matter.
Will an RV refrigerator run all day on battery power?
Some 12V compressor refrigerators can run on battery power, but their compressors cycle on and off. Enter estimated average running watts and equivalent operating hours per day, not necessarily 24 hours at full rated power.
Is this calculator suitable for boondocking?
Yes. It can help estimate off-grid RV battery endurance and the potential contribution from solar charging. Use a battery monitor and leave a practical safety margin for real trips.
Important Safety and Accuracy Disclaimer
This tool is for educational trip planning, not electrical system design or a battery safety assessment. It does not model voltage sag, Peukert effects, temperature derating, battery aging, surge loads, charging limits or battery-management-system shutdowns. Follow your battery, inverter and RV manufacturer's instructions. Consult a qualified RV electrical professional for wiring, fusing, charging and system sizing.