Can A Portable Generator Power Your Central Air Conditioner?

Last Updated on by Matt

what size generator to run air conditioner

Portable generators are great for powering small appliances and tools like those used for tailgating or camping.

And that’s all they’re suitable for, right? Wrong! A portable generator can be an excellent option for providing backup power to your house in the case of an emergency power loss.

You may not be able to power everything in your home, depending on your portable generator’s capacity, but you should be able to power the most important things.

In warm weather, one of the essential items to power is your air conditioner. Can your portable generator power your central air conditioner? Read on to find out what size generator is needed to run an air conditioner.

How many watts does central AC use?

central air conditionner next to a watt meter

To understand if your portable generator can power your central air conditioner, you first must know the required wattage.

You’ll also need to know both the starting wattage and running wattage capacity of your generator.

If the AC’s wattage is within the boundaries of the generator’s wattage, you should be able to go ahead and safely power your central AC.

For example, let’s say that your AC needs 6,700 starting watts and 6,000 running watts while your generator offers 9,375 starting watts and 7,500 running watts. Your generator would be able to power your AC because the wattage required is within the bounds of the wattage available.

However, it would be best if you also considered whether you need to power anything else concurrently.

In this example, you still have 2,675 excess watts. That may be enough to power a few other things, like an energy-efficient refrigerator and a sump pump.

It probably won’t be enough to power everything in your home, though.

Check out my Free Generator Wattage Calculator I created to calculate your wattage needs.

Starting Watts VS Running Watts

When trying to decide if your central AC and your portable generator are a perfect match, the most significant number is starting wattage.

Most central ACs need a pretty significant wattage for starting up, sometimes 1,000 watts over the running watts needed.

Your generator must be able to handle the starting wattage.

If you’re not sure what wattage your AC requires, look at the unit’s nameplate or check with the manufacturer.

It’s of paramount importance that you never guess or assume what the wattage is. If you try to power something that has a more significant need than your generator can handle, you’ll risk overloading it and potentially causing severe damage to anything plugged into the portable generator.

Worst case scenario, an overloaded generator could even result in a fire.

Make sure you know that your generator can handle it before attempting to power your central air.

Average Central Air Conditioning Wattage?

You’ll see an extensive range of wattage for central AC units.

Energy-efficient units, even large ones, may need as little as 2,000 watts while large, older units with less efficiency may require up to 10,000 watts.

There’s no one answer here. It doesn’t matter how many watts your friend’s air conditioner uses or how many watts the internet tells you is the average.

The only numbers that matter is the exact numbers for your specific unit.

Take the time to get this right, or you could end up seriously regretting it.

Which portable generators are powerful enough to power AC?

For most central AC units, you’ll need a generator with quite a bit of power.

Especially true if you want to power more than just the AC unit. Here are three good options:

1. Champion 7500-Watt Dual Fuel Portable Generator with Electric Start

Just like our hypothetical example earlier, this generator offers 9,375 starting watts and 7,500 running watts. That’s enough power to handle most central AC units.

It’s a dual fuel unit that runs on either gasoline or propane and it has a convenient electric start.

It has a volt guard, so you’ll be safe charging your cell phone or laptop when you’re running your AC without risk of damage to these sensitive electronics.

It has a gauge to help you monitor the power output to make sure you’re not pushing it beyond its limits.

For its size and capacity, this generator is also remarkably quiet at only 74 dBA.

Champion 7500-Watt Dual Fuel Portable Generator with Electric Start
  • Dimensions: 27.8" L x 28.7" W x 26" H | Weight: 200.6 lb
  • Noise Level: 74.0 dBA
  • Dual Fuel – Operate your 7500-watt portable generator right out of the box on either gasoline or propane, plus the unit holds 1.2-quarts of oil (included) and has a low oil shut-off sensor

2. Pulsar PG10000B 8000-Watt Dual Fuel Portable Generator

This dual fuel generator is a bit pricey, but it offers more power. With 10,000 starting watts and 8,000 running watts, it’s prepared to handle even really large central AC units.

In many cases, this capacity means that you will be able to power the entire home.

You should, for sure, have enough power to run several major home appliances at once.

It has an electric push-button start, and it’s entirely RV-ready if you sometimes want to take it on the road.

You’ll be able to use it power a window AC in your RV if desired.

You get as much power with this portable as you get in many stationary, standby home generators. But with all the conveniences of a portable.

Pulsar PG10000B 10,000W Peak 8,000W Rated Portable Dual Fuel Generator (Gas and LPG) with Electric Start
  • Gasoline: 10,000 Watt Peak, 8,000 Watt Rated
  • Propane: 9,000 Watt Peak, 7,000 Watt Rated
  • 420cc Engine w/ Electric Push Start

3. Briggs & Stratton 30545 P3000 PowerSmart Series Portable 3000-Watt Inverter Generator

This generator is a bit more affordable, but that comes with less power. With 3000 starting watts and 2600 running watts, it probably doesn’t have enough juice to power a central AC unit for a considerable home.

That said, it should have enough to power a smaller central AC system.

Designed to be fully portable with wheels and carry handles so you can bring it along for camping and tailgating when not using it at home for backup power.

This RV-ready unit has enough power to start up most window AC units for RVs.

A little display screen keeps you apprised of the power output and other relevant stats.

This unit is parallel-ready, so if you buy two of them, you can hook them together and double your power.

Depending on the wattage needs of your air conditioner, you’ll also be able to charge your cell phone simultaneously with the convenient USB port.

How about a window unit air conditioner?

Typically, a window unit air conditioner will take less power than a central AC unit.

The math, though, is the same.

You need to find out both the starting and running wattage the air conditioner needs and check to make sure that fits within your generator’s capabilities.

For example, let’s say your window AC needs 2,000 starting watts and 1,500 running watts and your Yamaha EF2000iSv2 generator offers 2,000 starting watts and 1,600 running watts.

That’s just enough power for you to run your window AC unit.

You won’t be able to power much else in the home, but your window AC should work just fine.

If you instead used the Champion 3400-Watt Dual Fuel generator with its 3,400 starting watts and 3,100 running watts, you would have enough power to run your window AC as well as a few other things.

The numbers in that example were on the high side for window AC units. Many smaller window air conditioners only need 500-700 running watts.

Even the smallest capacity generators should be able to handle the AC’s load.

Even the Sportsman 1000-Watt Inverter Generator with its 1,000 starting watts and 800 running watts would be up to the job with a little room to spare to power something else.

Regardless of the size of your AC unit, it’s vital that you know the actual numbers and don’t just guess or assume.

You can generally find the necessary wattage for your AC in the manual, on the unit’s nameplate, or by searching the model number online.

Don’t rely on estimated or average numbers. Find out the exact number, or you may regret it.

Conclusion

When you lose power during hot weather, the two top priorities for most people are running the refrigerator and the air conditioner. Whether you have a central AC or a window AC unit, you should be able to power them with your portable generator.

However, you must make sure of this before trying it.

You need to know both the starting and running watts the air conditioner requires. Make sure those numbers fit within the generator’s starting and running wattage capacity.

When you want to run more than just the AC, you’ll need to also add in the starting and running watts of whatever else you want to power.

Let me know in the comments if you have any questions about powering an AC unit with a portable generator!

Last update on 2020-07-04 Affiliate links & images from Amazon Product Advertising API

21 comments

  1. What is the most reasonably priced efficient back up home generator to install (not portable ) and expected price range to have installed. Is propane or natural gas recommended?

  2. I have a Generac 8000 with 10000 start up watts. My home is an older home that was built with no central air. Was added later and the wiring was not able to be done through the switch box but done externally below the meter. I measured the run amps of my system and the largest of 5 measurements was 19 amps. The start up amps measures 25 amps. From those stats, I believe my generator is more than adequate. Check me please.
    With all that said, my question is can I use an exterior transfer switch such as Reliance CSR302 or one similar. The reason I ask is I am not able to find an exterior t-switch that list central a/c as a use.
    Your article was extremely informative, thank you.

  3. Dennis did you ever look at a GenerLink Transfer switch, plugs into where your meter goes and then your meter hooks to that. Little pricey but solves the problem

    1. While these are a nice idea, call your power company and see if they will allow you to install them and use them before you buy one, some areas don’t allow them, if they don’t ask them why and complain, the squeaky wheel might get some grease and they might change there tune about allowing them.

  4. i am trying to figure out the correct generator for my needs.
    I am looking to power our home in case of emergency (hurricane, occasional power outages only, and would like to be able to run the central ac unit (3 ton) in our home.

    i would prefer a dual fuel inverter generator, for efficiency, versatility and quieter operation, but it does not look like inverter units are available in larger sizes needed to power a full size home a/c unit.

    My question is: could i use a 3500Watt inverter unit to run constantly for selected non-a/c circuits and a second similarunit to run only for 4-8 hours when i need to run the a/c. I dont think I would need to run the 2nd unit more than 12 hours/day here in North Carolina, to cool off our home.

    I am thinking of using an interlock switch for both generators, one for a/c only.

    What are your thoughts on this? think this will work ok?
    many thanks for your input.

  5. My standup portable a/c is pulling 8.5 amps running and 9.75 LR or Startup Amps. I have a WEN 1250 surge, 1000 watt running generator. It runs it but sometimes the compressor just barely kicks the generator into overload mode. I really like this small quiet generator and have no need to run other appliances at the same time. Could I use a “line interactive UPS” to handle the brief surge requirements? Once the van cools down the total compressor running time is greatly reduced so I’m sure I could do a deep cycle battery plus inverter (and a battery charger) to cover excess energy demand for the first 30 minutes of a/c cooling but I just wonder if a good UPS could accomplish the same thing with less complexity?

  6. Have a whole house 14kw Kohler with Load Shed – when I upgraded my central AC from 3 to 4 ton I had a problem with AC startup dropping out all on Load shed and almost stalling compressor. I bought a good meter with “in rush” detection which allowed me to check start up draw on compressor – start up current was 101 amps yes 101 amps. Started researching how to deal with this AC and Generator issue and after many online searches found Hyper Engineering’s SureStart soft start module. Had my AC tech install and my “inrush” current dropped to 25 amps….from 101 amps to 25 amps was almost unbelievable, I live in FL and AC runs almost constantly and module has been in for a year. Generator does a full load 20 minute run test every week and I AC / Generator / Load Shed works like a charm.

  7. I’m trying to figure out the correct generator as backup power that will run my furnace { 66k-70k BTUs } or a 3 ton A/c plus additional small house appliances.

    Currently looking at an 8000 watts portable generator with a 10K starting watts.
    Will the 8000 unit run a Lennox EL16XC1S036-230b03 / 3.0 ton A/C unit including the 1/2 HP blower motor?

    The worse power outage we had was three days during the winter.

  8. That is very informative.
    We have a Genset rated at 300Kva as backup for our church power which also use to run 2 unit of 50Tonnes (100Tonnes) Centralize AC.
    WE recent change our AC to 4 unit Inverter Type rated 25HP each (100HP)
    My concern is will running an AC on a Genset damage an Inverter Type AC?
    Thank you.

  9. we are now sourcing air conditioner with generation to be used for military tent , tent area 75 sq.m that need air conditioner with generator around 10 -20 ton to cover all inside area.

    1. You know most 20 ton AC’s will more then likely need a three phase generator and you will more then likely need a 480 volt unit, you can get that size AC in 3 phase 208 but the cords you will need are huge, an AC that size will suck down about 20,000 + watts running and you will need at least double that when it starts up, and depending on the fans you might add a few thousand more watts to the whole load Maybe a military surplus generator with a large CAT diesel engine, skid mounted in a sea can, or a tow behind unit, and consider a fuel delivery service, or lots of jerry cans, and a Deuce and a Half to bring it along for the trip you can get those military surplus as well.

  10. Matt, I have two panels in my garage and on one I have all the A/C units, let’s call it panel #1, (three A/C units for three zones) on one panel and heat for only the main unit, heat for the other two zones on the other, panel #2. Panels are supplied by two separate main cables into the house. My generator is connected to Panel 1. I cannot get any of my A/C units to work off the generator because the thermostat shows no A/C. It appears that the A/C will not work unless the heat side of the panel is also turned on. I can’t run the main A/C as it has to much power demand but I cannot get the small zone on either because the heat circuit is on the opposite panel. I have a Champion 7500 running watt generator. Heat always works fine on the main unit as there’s no compressor to run. Why can’t the thermostat get it’s power from the A/C side?

  11. Hey 🙂 great article and thank you so much that totally explains everything for me. I got all the answers that I needed In respect to knowing my wattage is and what amount of power only need vi

    And respect to knowing my wattage is in what amount of power going to need I respect my AC unit and a generator. for

    However I need to find a generator that’s with the solar powered or run by battery because I have a 350 square-foot dumb it’s 24 feet in diameter and it’s 14 feet tall turn on 300 and something square feet in there I think…

    However I need to find a generator that’s either solar powered or run by battery because I have 24 foot in diameter and 14 feet high the Dome …at a music festival next weekend… don’t allow gas or propane powered generators.

    I think it’s about350 square-foot we need to cool down and keep at a reasonable comfortable temperature For about 6-hrs to 8-hrs a day from 5pm – 11pm/mid-night each night fri sat and Sunday August 2-4….

    I need to source a solar powered generator or a battery powered on to use a portable air conditioning unit One of those 10,000 BTUs or 14,000 BTUs from Home Depot you can get that are inside and they blow out the air outside to event… when I was looking at draws 1500 starting in the pump is off at 1345…

    Maybe I could find a unit that draws less but I think my challenge is finding a portable generator that doesn’t require propane or gasoline I would power and AC unit that would keep a room at 350 ft.² feet cool 6-8 hrs a day

    Oh yeah by the way the dome that we have it sealed up entirely from all light which also means there’s literally no airflow and we can’t use swamp cooler’s or anything that needs a vent to be open in order for the cooling system to work.

    So that’s a challenge thanks for help if you can

    1. Do they allow diesel powered unit’s, you can get very quite diesel units and diesel is not any where near as flamable or explosive as gas or propane ? because to power two AC’s like those you listed you need like 3 kw / hour x 8 hours, and realistically more when you look at Peukert’s law with batteries because your not drawing them down over 20 hour, so unless your ready to move the unit with a forklift every time you need to charge it, there is not much option, if this is only used for short duration consider getting a rental diesel unit, most movie / film production suppy companies have very nice silent units, that are under 60dBA

  12. This article misses a huge consideration for powering a central AC unit with a portable generator. Voltage. Most Central AC requires 220-240 volts. Smaller generators (<6000 watts) are generally only 120.

    1. You can get small portable units with 240, the Generac GP3250 has 240 and it’s a sub $400 brand new generator, it might not be honda inverter quite but it does have 240 power.

    1. No, normally they are much lower, but they might not like the power quality of a generator, a good inverter won’t care but it seems the new units are missing good inverters so they might not even turn on.

  13. I have a Champion RP5500 portable generator Power Running 5500 W, Power Starting 6875 W I cannot read the nomenclature information on the Lennox Condensing unit can I use the Evaporator information to compute the Power Running W and the Power Starting W to see if my portable unit is enough to run the AC unit.

    1. How many tons is the unit a 5 ton for example will need about 5000 watts and 15,000 watts to start it, for smaller AC’s like those found in a home it’s approxamately 1000 watts per ton and 3 times the running load to start them up and when you start going over 10 tons the starting watts starts to go down to about double the running watts and even larger units like 50 ton AC’s will have more then one compressor so they can be turned on at diffrent times to reduce the starting watts.

      So with your generator you’ll be able to run about a 2 ton unit, 3 might push it over the limit.

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