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How Many Batteries and Solar to Run a 5,000 BTU Portable Air Conditioner?

How Many Batteries and Solar to Run a 5,000 BTU Portable Air Conditioner?


A small 5,000 BTU portable air conditioner is a popular choice for many RVers and vandwellers who don’t already have a roof-mounted system. But how many batteries and solar panels does it take to run a 5,000 BTU portable air conditioner for at least eight (8) hours a day?

5000 btu portable air conditioner
Black & Decker 5,000 BTU Portable Air Conditioner inside a house

How Many Batteries and Solar to Run a 5,000 BTU Portable Air Conditioner?

For this article, we are focusing on the Black & Decker 5,000 BTU Portable Air Conditioner (see it on Amazon) because it’s the best selling unit in this size. It costs $380.00.

Many RVers and vandwellers have purchased portable AC units in this size range for full time boondocking, but most power it with a generator.

But if you want to run this AC unit with solar panels and batteries, here’s what you’re going to need…

Total Purchase (not counting the AC unit itself): $6,910.00

Let’s Review the Above Parts

  • The Black & Decker 5,000 BTU Portable Air Conditioner will demand 3,800 watts (33 amps) to start up, and then about 850 watts (7.6 amps) to keep running. This unit is the most widely purchased brand, and highest rated portable AC unit in the 5,000 BTU range.
  • Four (4) 100 amp hour lithium phosphate batteries (also known as “LiFePo batteries”) will keep this AC unit for running about four (4) hours maximum. This is assuming these batteries are fully charged to begin with. If you want to use AGM (gel type) batteries, you will need eight (8) of these simply because these batteries can only be drawn down to 50% of charge.
  • 800 watts of solar panels designed to sit on the ground and tilt towards the sun will provide enough power to give you an additional four (4) hours of use from your portable AC unit. With both these panels and batteries, you should get about eight (8) hours of run time. Keep in mind you will be required to move these panels throughout the day to keep them turned to the sun.
  • Roof mounted solar panels can also work, however, you will need more panels. We suggest about 1,200 watts total. This is because roof mounted panels typically don’t tilt, or don’t tilt enough, and cannot be turned throughout the day.
  • You will have to keep the AC unit turned off during the morning sunlight to give them enough time to recharge your batteries.
  • We recommend the Victron SmartSolar MPPT 100/50 Controller. This unit is programmable to fit any combination/brand of battery and solar panel. It’s purpose is to make sure your batteries don’t overcharge and don’t overheat. It also Bluetooths with your phone to show you how much solar power you are generating and the current state of battery charge.
  • The Victron 3,000 watt Multiplus Inverter converts solar and battery power into the 110 to 120 volt power that the portable AC unit needs. The AC unit technically requires 33 amps (3,800 watts) of power to start up, which is technically higher than the inverter is capable of. But we find that most portable AC units, and even roof-mounted units, can actually start up using this brand and model of inverter.
  • The solar panel extension cables and connectors will be needed to connect the panels together in serial, and then connect to the Victron SmartSolar MPPT 100/50 Controller.
  • The red & black copper cables needed to connect the batteries together in parallel. You will need very thick copper cable at least 1/0 gauge to carry the full current without voltage loss. The 1ft length cables are specifically to connect batteries with each other, you will need 2 cables to connect two batteries together in parallel. You will also need 2 longer cables (2ft or more) to connect the Victron SmartSolar to the batteries, and another longer cable to connect the batteries to the Victron 3,000 watt Multiplus.
  • Not mentioned above is plywood board, about 1/4 inch thick, to create a box to house the batteries and mount the controller and inverter. Lithium batteries can be safely stored inside your vehicle with no harm to your health. In fact, these batteries will need to be stored where temperature will not fall below 32 degrees F.

Try Using a Portable Generator Instead

Most people use a portable generator to power a portable AC unit. They are much less cost, and require little to no installation.

Here’s what you’ll need to make it work for a 5,000 BTU portable AC unit…

Total Purchase (not counting the AC unit itself): $1,200.00

Inverter-generators run very quietly and come with a built-in inverter that converts generator power into the 110-120 volt electricity that a portable AC unit needs. They have a couple of standard, 3-prong outlets where you can plug an extension cord into and run into your vehicle. Generators in the range of 3,800 starting watts (surge watts) will cost between $800.00 at the low end, to $1,200.00 at the high. Don’t buy a generator with more wattage than you will need because generators are very heavy. A 3,800 watt generator loaded with fuel and oil will weigh about 120 pounds.

It may be better buy to two (2) 2,000 watt inverter-generators, and chain them together using a “parallel connection kit”. This means being able to have one generator connected to the other, to produce 4,000 watts. Each generator is lighter to carry, about 40 pounds (50 pounds with gas and oil), enough for smaller women to handle. And, on days when you don’t need to use the AC unit, you can just run one of the generators to power a microwave oven, an electric heater, or to recharge your electronics. Each of these 2,000 watt generators costs about $500.00, and the parallel connection kit usually runs about $80.00.

The heavy duty security cable/chain with lock is needed to prevent people from stealing your generator. These generators must be placed outside when running because they run on gasoline and produce exhaust. Some people place these generators inside the bed of their pickup truck, and then use the cable/chain to lock them in.

A generator tent is used to keep your generator dry when it’s raining.

Most guys buy a single 5-gallon gasoline jug. But, these can be heavy when full and may cause you to spill when trying to pour. Think about buying a few 2-gallon jugs instead. Most portable inverter-generators will run for about 8 hours on a single gallon of gas.

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