How much battery capacity do I need for boondocking?

Add up what you actually run rather than guessing. The weekend example on this page comes to about 635Wh a day for a fridge, lights, a fan, phone charging and two hours of TV, so build your own total from the table above. At 12.8V nominal with 80% DoD, every 1,000Wh of daily draw needs about 98Ah of LiFePO4, so that example needs roughly 62Ah per day and about 124Ah for two days with no sun at all. Most serious boondockers settle on 200-400Ah of LiFePO4 at 12V paired with 200-400W of solar panels. Our off-grid load calculator helps you tally every appliance into a precise daily Wh budget.

Should I upgrade my RV batteries from lead-acid to LiFePO4?

If you boondock regularly, the upgrade almost always pays for itself. A typical RV has two Group 24 lead-acid batteries, about 150Ah total at 12V. Concorde recommends running AGM no deeper than 50%, and Trojan recommends 20-50% for flooded, so that is 75Ah you can actually use. One 200Ah LiFePO4 battery gives 160Ah at 80% DoD, more than double, at half the weight. It also lasts far longer in cycles: U.S. Battery prints 675 cycles at 80% depth of discharge for its flooded batteries, against the 3,000-5,000 deep discharge cycles Battle Born prints for its LiFePO4. It also charges faster — see the difference with our battery charge time calculator .

Can I run my RV air conditioner on battery power?

Technically yes, but the energy numbers are brutal. Dometic rates its Penguin II 13,500 BTU rooftop unit at 12.5 running amps for the compressor plus 3.5 for the fan, on 120 volts, which is about 1,900W with everything turning. Put that through this calculator on a 500Ah LiFePO4 bank at 12V and you get 2.4 hours, which empties the bank rather than merely denting it. Most off-grid RVers skip AC entirely and use fans, shade, and ventilation instead. If you must have battery-powered AC, look at 48V systems with 400+Ah banks and a large array: serious hardware for serious comfort.

RV Battery Runtime Calculator — LiFePO4 House Loads

5 min read

RV battery runtime is the difference between a relaxing weekend off-grid and a frustrating scramble for a hookup site. The RV battery runtime calculator below tells you whether your house bank can handle your camping style, using the voltage your batteries are actually rated at: pick LiFePO4 and a "12V" bank is treated as 12.8V nominal, so 200Ah holds 2,560Wh. Our RV battery sizing guide covers multi-day boondocking strategies and solar integration.

Recreational vehicle with battery compartment, window bay, and dual-axle wheels.

RV Appliance Power Draw Reference

RV Appliance	Watts	Typical Daily Use	Daily Wh
LED interior lights	5-20W	5 hours	25-100
12V fridge (compressor)	40-60W running, cycling about 33%	24 hours	about 320
Water pump	40-100W	15 min	10-25
Vent fan (Maxxair/Fantastic)	5-40W	8 hours	40-320
Phone/tablet charging	10-20W	3 hours	30-60
TV (12V, 24")	30-50W	3 hours	90-150
Laptop charging	45-65W	2 hours	90-130
Coffee maker (inverter)	600-1,200W	10 min	100-200
Microwave (inverter)	800-1,500W	10 min	130-250
Electric blanket	50-100W	8 hours	400-800

Typical wattages are our own estimates; check your appliance's nameplate.

The biggest surprise for most RVers is still the fridge, and it is smaller than people expect. Dometic prints 1.11 amp-hours per hour at 12V for its CFX5 35, which works out to 13.3W average, or about 320Wh over 24 hours at a 90F ambient. A large residential-style RV fridge is a different animal: the U.S. Department of Energy reference 18.1-cubic-foot top-freezer uses 363.5-404 kWh a year, roughly 1,000-1,100Wh a day. Check which one you have before sizing anything.

RV 12V electrical system diagram showing battery bank, fuse panel, inverter, and loads. — A typical RV system routes 12V DC through a fuse panel for lights and fridge, while the inverter supplies 120V AC outlets from the same battery bank.

Example: Weekend Boondocking

You are boondocking for two nights with a 200Ah 12V LiFePO4 battery bank and 200W of rooftop solar. Here is a realistic daily energy budget:

Fridge: about 320Wh, from Dometic's printed 1.11 amp-hours per hour at 12V for its CFX5 35, about 13.3W average at a 90F ambient. Lights: 60Wh. Fan: 120Wh. Phone charging: 40Wh. Water pump: 15Wh. TV for 2 hours: 80Wh. Total daily draw: about 635Wh.

Battery bank capacity: 200Ah x 12.8V x 80% DoD = 2,048Wh usable, or 1,843Wh once 90% system efficiency is applied. That covers a day with 1,208Wh to spare, and two nights still fits inside the bank before you need to recharge.

Solar is what stretches a trip past the bank's own reserve. A 200W array recovers a useful share of that 635Wh on a clear day and much less under cloud, so treat it as a top-up rather than a guarantee, and size yours for your own location and season.

On a run of grey days, reduce loads: skip the TV, and pre-cool the fridge on shore power before you leave.

Worked Examples

Weekend Boondocking Power Budget

Context

You have a 200Ah LiFePO4 bank and plan two nights off-grid. Your loads: 12V fridge (13.3W average, the figure Dometic prints for its CFX5 35), LED lights (15W for 5hrs), phone charging (10W for 2hrs), and a water pump (60W for 0.5hrs/day).

Calculation

Daily energy: (1.11 x 12 x 24) + (15x5) + (10x2) + (60x0.5) = 320 + 75 + 20 + 30 = 445 Wh/day, an average draw of 18.5W

Two days: 890 Wh

Battery delivered: 200 x 12.8 x 0.80 x 0.90 = 1,843 Wh

Days of autonomy: 1,843 / 445 = 4.1 days

Interpretation

Four days of autonomy from a single 200Ah battery, because the fridge draws far less than most people budget for. Your two-night trip fits with plenty of reserve. Add a laptop and a TV from the table above and it drops to between two and a half and three days.

Takeaway

For longer boondocking stretches, add solar. Size the panel array with our solar panel and battery sizing calculator to match your daily energy use.

Can a 400Ah Bank Run RV Air Conditioning?

Context

Your rooftop AC is a Dometic Penguin II 13,500 BTU: 12.5 compressor amps plus 3.5 fan amps at 120V, about 1,900W running. You have a 400Ah 12V LiFePO4 bank with a 2,000W inverter. You want to know how long the AC runs on battery alone.

Calculation

Load: (12.5 + 3.5) A x 120V = 1,920W

Bank: 400 x 12.8 = 5,120 Wh; usable at 80% DoD = 4,096 Wh

Delivered at 90% efficiency: 3,686 Wh

Runtime: 3,686 / 1,920 = 1.9 hours

Interpretation

Under two hours, and that is with the fan counted. Leave it out and the runtime reads about 28% too long. AC is the single biggest load in an RV and batteries alone cannot sustain it. You need either shore power, a generator, or an extremely large solar array.

Takeaway

Running AC off-grid requires serious solar investment. Estimate the panel count needed with our solar panel output calculator — expect 2,000W+ of panels for meaningful AC runtime.

Frequently Asked Questions

Glossary

Boondocking

Camping in an RV without hookups — no shore power, water, or sewer connections. All electrical needs must come from batteries, solar, or a generator. Also called dry camping or off-grid camping.

House Bank

The battery bank in an RV dedicated to powering living area loads (lights, fridge, outlets). This is separate from the chassis battery that starts the engine. House banks range from 100Ah in small vans to 800Ah+ in large motorhomes.

Daily Energy Budget

The total watt-hours consumed per day by all RV appliances. Calculated by multiplying each device's wattage by its hours of use. This number drives battery and solar sizing decisions.

Planning your solar setup? The camper battery sizing calculator matches solar panels to your battery bank specifically for RV use.

Runtimes here use the nominal voltage the makers print, 12.8V per 12V block for LiFePO4, and for lead-acid they add a discharge-rate correction fitted to Trojan's, Lifeline's and Victron's published discharge tables, reproducing their printed points within about 10% for flooded, 6% for AGM and 2% for gel. RV battery sizing comes down to one question: what loads are you willing to give up? Size your bank for the loads you refuse to cut, add solar for daily recovery, and keep a generator for cloudy stretches. Run the numbers above with your actual loads — not wishful thinking — and your boondocking trips will be comfortable instead of stressful.

More Battery calculators

Browse all battery calculators — LiFePO4, lead-acid, AGM, and lithium-ion runtime, charge time, and capacity sizing.

Last updated: September 23, 2026

Written and maintained by Dan Dadovic, Commercial Director at Ezoic Inc. & PhD Candidate in Information Sciences. He works professionally as Commercial Director at Ezoic Inc., leading revenue strategy across digital publishing.

Disclaimer: Calculator results are estimates based on theoretical formulas. Actual performance varies with temperature, battery age, load patterns, and equipment condition. For critical electrical work, consult a licensed electrician.

Methodology reviewed by Doc. dr. sc. Damir Topić, Assistant Professor, FERIT Osijek.