How Many Batteries Do You Need to Run an RV AC?

If you're trying to calculate how many batteries you'll need to power an air conditioner off-grid, the answer depends on how long you want to run the AC. Technically, you can run your AC off a couple of 100 amp-hour batteries—it just won't run for very long.

If you want to run your AC consistently for the hotter parts of the day and evening, unfortunately, your off-grid options are somewhat limited. A generator will typically be your best bet for air-conditioned boondocking.

Not ready to settle on a generator? Read on below for an overview on what it takes to run an AC on RV battery power.

How Many Batteries Do You Need to Run an RV AC?

In short: a LOT. The required battery bank size depends on several factors, including how much power your AC demands, how hot your camping location is, how long you plan to run your AC, and what type of batteries you have. Lithium ion batteries are by far the best option for running such a high-draw appliance. They are lighter, more efficient, and longer lasting than lead acid batteries.

To figure out exactly what size battery bank you need, start by considering the amperage draw of your AC and how many hours per day you plan to run the unit.

This means that you'll need 450 amps per day from your battery bank in addition to the battery power it takes to run everything else in your RV. So if you ran your RV off a 200 amp-hour battery bank without the AC, you'll need a 650 amp-hour battery bank to run the AC and your typical load. We'll round up to a minimum 700 amp-hour battery bank.

Essentially, you'll need to determine how many amp-hours you'll devote to your AC unit, then add a battery bank sufficient to support the unit in addition to everything else you normally run.

How Much Does It Cost to Run an RV AC Off Batteries?

Obviously, a battery bank of this size won't come cheap, and depending on the size and weight limitations of your RV, it may not be possible to add that many batteries to your rig.

Of course, even if you do manage to bump up your battery bank enough to run your AC for a few hours, you then face the problem of recharging your batteries. To recharge, you would typically use a generator, shore power, or solar panels.

Presumably, you aren't thrilled at the idea of using a generator and you don't have shore power available, which is why you want to run your AC via batteries in the first place. Solar panels are likely going to be your best option. This is still a rather costly project, but it's more practical than draining your batteries with no way to replenish them. You can check out more information on what's involved in running your AC off solar power here.

Tip: A battery charger like the Redarc BCDC can help keep your trailer charged up on the road, plus it's solar power capable when you're boondocking. (Note: Only unregulated solar panels may be used with the Redarc BCDC, which includes its own MPPT solar regulator.)

To run your AC off your batteries, you'll also need an inverter to change your battery bank's 12V DC power to 120V AC power for your air conditioning unit, so that's another added expense.

Also keep in mind that batteries become less effective at maintaining a charge over time. Repeatedly draining your batteries for your AC will require you to charge the batteries more often, which will in turn decrease the lifespan of your batteries and require you to purchase a replacement sooner.

All things considered, can you run your AC off of your batteries? Technically, yes. As long as you have a large enough battery bank and an inverter, you can run your RV's air conditioner for at least a limited amount of time. Is this a sustainable, cost-effective solution? Not really.

Our advice? If you can't live without your AC, invest in a good generator. They're more than capable of running your AC unit without breaking the bank or killing your batteries.

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