No, for the most part you will not be able to run your RV air conditioner on battery power. An air conditioner requires a lot of electricity just to start up. It also requires a lot just to run for an hour. It is possible, however to run air conditioning on batteries. You just need a lot of battery power, along with a lot of solar panels, to help offset your battery draw.
Can I Run My RV Air Conditioner on Battery Power?
A 15,000 BTU air conditioning unit is what most RVs come equipped with these days. Each of these units requires a minimum of 3,500 watts just to kick start a unit. It then takes about 1,500 watts to keep that unit running.
This means you will need at least a 4,000 watt DC-to-AC power inverter, to convert your battery power to usable AC electricity. Most RVs do not come equipped with an inverter of that size. Most RVs do not even come equipped with an inverter of any kind. Those that do, usually come with an inverter ranging from 1,000 watts to 2,000 watts.
You can also add a “soft start device” (see it on Amazon) to your air conditioning unit to lower the required starting wattage. Thus, a 15,000 BTU AC unit which would otherwise require 3,500 starting watts, may only need 1,500 to 2,000 watts if equipped with a soft-start.
Only the higher-end RVs come with equipped with a power inverter. These are usually larger fifth-wheel trailers, Class A motorhomes, and higher end Class B vans. Most fifth-wheel trailers and Class A motorhomes come with two to three air conditioning units. Thus, in order to run all two or three air conditioning units, you will need a larger power inverter, perhaps as high as 7,000 watts. No RV or motorhome comes equipped with that high of an inverter.
How Many Batteries Would I Need?
If you had three 100 AH (amp hour) Lithium Phosphate batteries, along with a 7,000 watt power inverter, you could run two 15,000 BTU air conditioning units for about 1 hour. But that will also require you to have about 1,500 watts of solar panels on the roof, to help offset that electrical power draw. On top of that, it would have to be a sunny day in the middle of summer, when you get the best overhead sunshine.
So, if that system will get you just 1 hour of running two air conditioning units, then think about what you will need to run that system for 8 hours. Think about what it would take to run just one air conditioning unit for 8 hours.
Read our other article, “How Much Battery Power Will I Need for Boondocking?”
Why Lithium Phosphate Batteries?
Lithium Phosphate batteries can be drawn down to zero state of charge without suffering damage. Compare that to flooded-cell batteries, or even AGM batteries, which can only be drawn down to 50% state of charge.
In order to get 8 hours of running an air conditioner on battery power, you will need a lot of batteries. A typical 12 volt flooded-cell battery, delivering 100 AH, weighs about 50 pounds. A typical 12 volt lithium battery, delivering 100 AH, weighs about 30 pounds. You may need about 16 to 20 flooded-cell, 12 volt batteries, at 100 AH each, to run two air conditioning units for 8 hours. That could end up weighing as much as 1,000 pounds, and take up a lot space. By comparison, you will need about 8 lithium batteries at 100 AH each, weighing 240 pounds total. That’s a huge difference.
Most travel trailers, either bumper-pull or fifth-wheel models, don’t offer that much cargo carrying capacity. You’d have to buy a toy hauler to get that much capacity, let alone the weight of your other stuff (clothes, appliances, tools, electronics, etc.)
It’s an Extremely Expensive System
A typical 12 volt, 100 AH lithium phosphate battery costs about $1,000.00 each. That means about $8,000.00 in batteries just to get you 8 hours of running two air conditioning units.
That doesn’t count the expense of buying a 7,000+ watt power inverter, which can cost between $1,200.00 to $2,000.00. That also doesn’t count the 1,500 to 2,000 watts of solar panels on your roof, to replenish those batteries while running your air conditioning. That will cost roughly $1,500.00 to $2,000.00 (usually $1.00 per solar watt).
When you include the costs of additional parts (copper wire, battery monitor, 2-way or 3-way transfer switch, solar panel mounting hardware, etc.) you’re looking at spending $11,000.00 to $12,000.000 dollars, just to be able to run two air conditioning units for only 8 hours a day.
And again, that’s assuming you’ll have a bright a sunny day to recharge those batteries.
You can reduce that battery expense by going with Tesla car batteries. Tesla batteries can deliver more power at lower costs. But, they will also require installing a 24 volt system, along with a converter to reduce the final output to 12 volts. There is actually a mobile RV technician that installs Tesla battery banks for RVers.
So Why Bother With Solar Panels and Lithium Batteries?
Most RVers utilize solar panels and lithium batteries to run their DC electrical needs, which are the lights, fans, water pump, power awning, power tongue jack, and other light-duty electrical needs. These provide all the power necessary to boondock comfortably for weeks at a time.
Most boondockers don’t camp in places where they’ll need air conditioning. That is, they camp in higher elevations during the summer where they can get relief from the heat.
If a boondocker still needs AC electrical power, it’s usually for something light duty, like powering a blender, a C-PAP unit, or a television. These things can be run from battery using a smaller power inverter of 500 to 1,000 watts. This also assumes they have a modest sized battery bank of about 200 to 300 AH, and a modest sized solar panel array of 400 to 800 watts.
Solar power, combined with a decent sized battery bank, and a small to medium sized power inverter, is still affordable for RVers who spend most of their time boondocking.
Read our other article, “How Many Solar Panels Do I Need for Boondocking?”
If You Need Air Conditioning, Get a Generator
This is what generators are for. They’re for powering heavy-draw appliances like air conditioning units and microwave ovens. Sure, generators can be expensive themselves, along with being expensive to run for long hours during the day. But, if you want to consume a lot of electricity while boondocking, it is still by far the cheaper alternative.
Read our other articles, “Do I Need a Generator for Boondocking?”, and “How Big of a Generator Do I Need?”
I run 2 1500 BTU AC with 10 Lithium ion Batteries and 1000 watts of Solar panels. Dry camping on BLM land nobody wants to hear a generator running all night long.
My System cost: $14,000. For a 36 foot RV. But when it’s 110* outside it’s 68* inside. I also have a RV evaporative cooler that uses water for dry climates. Usually the Desert cools down at night so I will just uses the swamp cooler.
Terry, getting a 40 to 50 degree temperature drop inside your rig is pretty darn good. I also have two 1500 BTU ACs, but I can’t seem to get any better than a 20 degree drop. What AC units are you running?
Good article and very accurate info. If it wasn’t obvious, there is no value in buying a huge lithium bank to power standard RV AC units which are notoriously inefficient.
What was not covered, and is less expensive, are more efficient AC unit alternatives that CAN be run from your standard SLA battery bank or small LiFePO bank.
If you remain mobile in your RV, replacing the standard Dometic or Coleman units with a LG mini split model LMU18CHV 2-LMCN078HV-NG would be significantly more efficient and less expensive than buying a $10k battery bank or $14k for a Tesla battery. The downside is you will need to find a place to put the condenser unit and modify to exhaust it. Easily done on a 5vr unit garage door.
If you really want to go cheap and your not mobile, you can buy 1 or 2 window units that are 5k BTUs – 10k BTUs and will easily keep the RV cool in extreme heat and run off your standard boondocking battery bank. The AC units run from $200-500 bucks. This works if your seasonally mobile too, just have to be creative in your mounting it.
I use an 8k BTU smart unit from GE ($289) in my 40ft 5vr in the main room and it easily keeps that area cool 76°ish in Arizona 110° heat from my SLA battery bank. Can turn it on/off from my smart phone from anywhere.
The article also didn’t cover the use of an easy start on the factory AC units which may allow a user to use a smaller inverter like a 3k unit to handle the start up surge.
Food for thought.
Good point on adding a soft start. You’d think AC manufacturers would just build that in.
has anyone tried to run a single 15K dometic ac unit in a fifth wheel while trailering. what size inverter could handle this an how many batteries? We want to travel west but I suffer from heat related issues. We usually stop an fix meals in the rv when we travel an would like to run the ac while going down the road. running a generator while driving does not seam like a good idea. plus there is no place om my 5ver that would be safe.
Hi Steve,
Echoing Dana’s question, is it correct to just halve your numbers to run one 15000btu ac for eight hours? Meaning a ~4000watt inverter and four 100ah lithium-ion batteries, assuming we keep 1500-2000watts of solar panels constant?
Btw, thanks so much for your breakdown, figuring out the solar panel system is like Mandarin to me.
If one has any DIY skills, You can purchase 4x280AH LifePo4 Cells from AliBaba/China for $500 from very reputable dealers, $100 for a BMS, and another $100 for Box/Misc parts and you can build a 12v 280AH LifePo4 Battery for roughly $700. 3 of these for $2100 for a 840AH LifePO4 Battery setup that will power this same AC for 8 Hours. A commercial LifePo4 Solution from BattleBorn or another Manufacturer that is dictated in this Article would have cost me $9000. This is what I’m doing and it only requires basic DIY knowledge where you only need to be able to connect some wires together and do basic electrical work. You can see more details on DIYSolarForum.
This article severely inflates the costs and requirements. First you said you would need a 4000W inverter (then later a 7000W), but the running load is only 1500W. Inverters (just like generators) can take an increased load for starting (very short time). Most 2000W inverters are rated for around 3500W starting load. As long as it has the starting load rating, you could go as low as a quality 2500W, but more comfortably with a 3000W inverter.
You also advised battery cost for lithium ion. While they are nice and will last longer, many campers are only using their rig occasionally, and may only need A/C usage very occasionally. This means that SLA batteries are very acceptable. Your $8000 figure for battery cost would drop to about $1500 (current SLA cost is about $170/100Ah). As well, you claim that you will need more SLA batteries than Lithium, but they are each rated for 100Ah, which means you need the same amount. Yes, you can draw down Lithium closer to 25%, where SLA shouldn’t go much past 50%, but if this is a once or twice a year situation for many campers, drawing the SLA down to 25% won’t be that big of an impact to life.
Your entire article is written seemingly mocking the idea of using batteries for an A/C. However, some people don’t have an option, don’t want the noise and need to refuel, and are looking for solutions. Your article would be more effective if you focused on what you CAN do and how different options can benefit people in different situations. Ignoring much cheaper options because you believe Lithium is the only option valid for anyone or any situation is not helpful.
Yes, a generator is helpful in many situations (the majority). However, I am for example setting up my trailer for usage once/week on a remote property with neighbors that don’t want to hear a generator. That means I just need to have a strong enough inverter for the A/C in the summer nights in Florida for one over night, and the solar panels can have 6 days to recharge the batteries. As well, the batteries can be off trailer, so weight is not an issue.
Please keep in mind that not everyone has the same needs.
I sure like Chris’s attitude. I am having trouble with this exact problem, it always comes down to cost. I need the contact email for Chris :))
You will not need a 4000watt Inverter as most inverters can take increased starting watts that are much higher than its rated power output. The 3000 watt inverter I’m looking at can handle 5000w for 5s. Plus a lot of Aircons these days are inverter with soft start also so a 2000W inverter is more than enough.
My vehicle was built professionally with long-term boondocking in mind.
First and foremost the body is constructed from composite sandwich panels, 60 mm thick, with double glazed windows (real glass) and a solid door that isolates the cab from the cabin. So good insulation is the key here.
Next I opted for a 12 volt AC located under one side of the dinette. It uses much less power than traditional roof-mounted AC units and cycles on and off even in the Arizona heat.
I have 1 kilowatt of solar panels that feeds two 400 amp lithium batteries.
I can run my AC for many hours and have never run the batteries down.
That’s awesome Peter. Having excellent insulation allows you to rely comfortably on low-voltage cooling systems. Too bad most RVs have paper thin walls!
First, see Chris’s comment. These numbers are very old; prices have come down a lot.
The Chinese are flooding the market with LiPo batteries. I’m in the process of purchasing a 5kWh LiP 48V battery for $1500—about 30% of the cost you quoted above.
Plus, the thing to do is install a mini-split heat pump. I’m in the process of purchasing one at 38-SEER—perhaps 4x more efficient than the AC units that are bundled with RVs today. It will cost about $1300 for the unit. Its required running power is about 900W — easy for a few larges solar panels to handle with capacity left over to charge the batteries. Can’t use the terribly inefficient ACs out there; have to look at the residential market.
There are other pieces needed but the whole article needs to be updated and re-written, in my view.
Thanks for finally an honest review of this never ending question and for slowing down what provides a constantly producing amount of click-bait for Youtube channels from misguided wishes. Also not to forget that if you need 1500W to power the AC units, you need an additional 1500W to recharge the batteries from powering them the night before. Then there is the standard often 150aH per day load of just LED lighting, portable fans, computers, tablets, etc. I believe most who have any luck with a setup like this at all end up having to run the generator or engine a lot because the solar just can respond to this kind of demand. I have 900 watts and the thought that just 400W more is all I need to run 2 AC units is a bit far-fetched I believe. I’d say that 3000W of solar is a more realistic number, assuming you have the battery capacity.
A good short summation might be, if 50A of 120V service pouring into your thin-walled living domain won’t keep you cool, how could one expect the same or more from a box of repackaged flashlight batteries.
Don, I’ve seen RVers with about 1,000 watts of solar on the roof plus three (3) 100AH Battleborn batteries, and be able to run one AC unit. However, they can only run it for about one hour. So… if you want to run your AC unit for eight (8) hours a day, you are going to need a heck of a lot of battery power and solar to pull it off. I do know of a few RVers that have Tesla car batteries in their rigs along with 1,500 to 2,000 watts of solar both on the roof and as ground units. So, it can be done, if you have the money to spend.
People who tend to enjoy 1 hr of A/C soon lean toward 8, particularly when a whole night of sleeping is involved. Give them 8 during the night and it might be good also for 4 more to watch their favorite show or binge on youtube, then add 4-8 more. Then it’s hard to both recharge a binge evening of 8 hour battery depletion while powering the A/C running during the daytime too. This “reduced hour cooling cycle” remains impractical for the lifestyle of the majority of people who demand A/C units. It’s like my best friend told his doctor when he came down with diabetes and was told he could have only 8 oz of meat per week. He told the doctor “you can just keep it” (meaning the steak). So give me only 1-4 hours A/C use per solar recharge cycle for a $10,000 – $20,000 investment, then “you can just keep it”.
The generator size depends on your AC unit’s starting and running wattage. By consulting the AC specifications, you’ll confidently determine the ideal generator size. Typically, a 2,000 to 4,000-watt or higher generator will handle most RV AC units with ease.