Four 12 volt batteries is the very minimum needed to run a rooftop RV air conditioner. But then, that will only run an air conditioner for about 1 hour maximum. Of course, it depends upon the type of battery. Flooded cell batteries, AGM batteries, lithium phosphate batteries, each offer different variables that can extend or decrease air conditioner run time.
How Many Batteries Do I Need to Run an RV Air Conditioner?
If you want to run your RV air conditioner on battery power, it depends on the type of battery…
Flooded Cell Batteries
Typical flooded cell batteries (the kind you pour water into), offer the least amp hours (AH). 12 volt flooded cell batteries can only be used down to 50% of charge. If you continue draining a battery below that level, you slowly damage it’s ability to recharge. Hence, if a 12 volt flooded cell battery is advertised as offering 100 AH, you really only have 50 AH of usable power.
6 volt golf cart batteries (flooded cell variety) typically offer greater amp hours, anywhere from 200 to 400 AH. But they also have similar discharging limitations. Generally, you don’t want to discharge below 50% charge.
AGM batteries can be discharged down to about 20% of charge. Hence, a 100 amp hour AGM battery can get you up to 80 AH of usable power. That translates into longer air conditioner run time.
But, how many AGM batteries do you need to run that air conditioner? Still, at least a minimum of four, just to run it for one hour, possibly up to an hour and a half?
Lithium Phosphate Batteries
Brands like Battleborn, Relion, and Renogy are popular lithium phosphate batteries for RV use. Most of these come in 100 AH sizes. These can be discharged all the way down 0% charge without suffering damage to the battery. This means more air conditioner run time.
Four lithium batteries will likely yield you two hours of air conditioner run time at the most.
The bigger advantage of lithium batteries is that they are much more light weight. You can stack more of them in your trailer or motorhome than you could with much heavier flooded cell or AGM batteries.
Tesla Battery Modules
People are just now exploring the idea of installing used Tesla battery modules into their RV. These are Lithium Ion batteries, as opposed to Lithium Phosphate. A typical Tesla automobile has a battery pack containing 16 modules. Just one of these modules operates at 24 volts instead of 12 or 6, and typically offer between 200 to 220 AH. A single Tesla module offers the same power as four lithium phosphate batteries offered by Battleborn, Relion, or Renogy, but costs half the price.
Just one Tesla battery module can run an RV air conditioner for about three hours.
There is a mobile RV technician who installs Tesla car batteries into RVs.
How Many Batteries Do I Need for 8 hours?
Boondocking requires plenty of battery power. How many batteries are needed to run an RV air conditioner for 8 hours?
Flooded Cell Batteries – Look for about 20 to 24 of these batteries in 12 volt, 100 AH varieties. You will need about 2,000 pounds of cargo carrying capacity, preferably centered over the trailer wheels, or centered between the motorhome wheels. If using 6 volt batteries, at 200 AH, you will need about 12 to 14 of these batteries. Expect about similar overall weight, as these are heavier batteries.
AGM Batteries – Look to getting between 14 to 18 of these batteries in 12 volt, 100 AH varieties, or about 8 to 12 in 6 volt, 150 AH varieties. Expect similar weight burden.
Lithium Phosphate Batteries – Expect to get between 12 to 16 of these batteries in 12 volt, 100 AH varieties. These batteries are half the weight, so expect to add another 600-800 pounds of cargo weight to your rig.
Tesla Battery Modules – Look to buying about three Tesla battery modules to run an air conditioner for 8 hours. Each module generally weighs about 60 pounds, so look to adding about 180 pounds of cargo weight.
Where Can I Buy Tesla Battery Modules?
They are not easy to obtain, but there are online retailers. You can just Google, “where to buy Tesla battery modules”. Or, you can contact “The BoonDoctor“, a mobile RV technician who installs Tesla battery modules into RVs.