Generator Size for 50 amp RV with 2 AC Units
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It would be perfectly fine to run your 2 A/C units on a 4,000-watt generator if power surges (during startup and when condenser kicks in) were not an issue! Common RV air conditioners are rated at about 1,300-1,500 watts and now let’s multiply it by 2, you are probably looking at a 3,000-watt generator if you utilize a soft-starter or a 6,000-watt generator if you do not.
Air conditioners are quite power-hungry devices, so let’s take a look at what we are dealing with here. We will be looking at popular Dometic and Coleman models:
Dometic
| Model | BTU Rating | Running Amps | Surge Amps |
| 64310C | High Efficiency | 10.5 | 63.0 |
| 64315C | 13,500 BTU | 12.5 | 61.0 |
| 64310C | High Capacity | 12.5 | 61.0 |
| 640310 (paid link) | High Efficiency | 8.8 | 56.0 |
| 6550015C | 13,500 BTU | 12.5 | 61.0 |
| 6550016C | High Capacity | 12.5 | 61.0 |
| 651815 (paid link) | 13,500 BTU | 12.5 | 61.0 |
| H540315 | 13,500 BTU | 12.7 | 68.0 |
| H540316 | 13,500 BTU | 13.2 | 79.0 |
| B59530 | High Efficiency | 8.6 | 50.0 |
| B57915 (paid link) | 13,500 BTU | 12.4 | 63.0 |
| B59516 (paid link) | 15,000 BTU | 13.3 | 66.0 |
| B59196 (paid link) | 15,000 BTU | 13.3 | 66.0 |
| 479516 | 15,000 BTU | 13.3 | 66.0 |
| 15027-W | 15,000 BTU | 11.0 | n/a |
| 15032-B | 15,000 BTU | 11.0 | n/a |
| 15025-W | 15,000 BTU | 11.0 | n/a |
| 15030-B | 15,000 BTU | 11.0 | n/a |
| 15028-W | 15,000 BTU | 13.3 | 66.0 |
| 15033-B | 15,000 BTU | 13.3 | 66.0 |
| 15026-W | 15,000 BTU | 13.3 | 66.0 |
| 15031-B | 15,000 BTU | 13.3 | 66.0 |
| 441003 | 10,150 BTU | 8.9 | n/a |
Coleman
| Model | BTU Rating | Running Amps | Surge Amps |
| Mach 15 HP2 | 13,500 BTU | 15.5 | 63.0 |
| Mach Power Saver | 15,000 BTU | 10.8 | 58.4 |
| Roughneck | 13,500 BTU | 15.3 | 63.0 |
| Mach 15+ RV (paid link) | 15,000 BTU | 15.3 | 63.0 |
| Mach 3+ RV (paid link) | 13,500 BTU | 15.3 | 63.0 |
| Mach I Power Saver | 11,000 BTU | 9.9 | 45.6 |
| Mach III Power Saver | 13,500 BTU | 11.2 | 58.4 |
| Polar Mach 13.5K Units | 13,500 BTU | 15.5 | 63.0 |
| Polar Mach 15K Units | 15,000 BTU | 15.9 | 63.0 |
| Polar Mach Polar Cub | 9,200 BTU | 11.5 | 58.4 |
| Polar Mach 15K Heat Pump | 15,000 BTU | 15.9 | 63.0 |
| Polar Mach 13.5K Heat Pump | 13,500 BTU | 15.6 | 63.0 |
| Mach 8 13.5K A/C | 13,500 BTU | 12.1 | 63.0 |
| Mach 8 15K A/C | 15,000 BTU | 12.7 | 63.0 |
| Mach 8 13.5K Heat Pump | 13,500 BTU | 12.5 | 63.0 |
| Mach 8 15K Heat Pump | 15,000 BTU | 12.7 | 63.0 |
** Important! Specifications and product info are subject to change without notice.
** Disclaimer. Information in ElectricProblems.com specification tables is approximate and could contain an error. They also don’t include all available brands and products. Please consult the manufacturer for the latest and most accurate information.
Inverter-generators
So, how big of a generator do you need to run your RV air conditioner? Two 2,000-watt inverter-generators wired in parallel can make an excellent setup up while giving you the full benefit of 4000 watts when you need it.
Most people recommend Yamaha or Honda brand due to their outstanding reputation (great, quiet, and last a long time), but brands like Champion and DuroMax, could save you some money for basically very similar equipment.
Another reason for using two inverter generators is the weight issue. Bigger size generators are much heavier and bulkier. Storage space is also an issue with larger generators. How do you even lift it???
A parallel kit allows you to connect two generators and receive the same power as a bigger unit. Only lifting them individually is much easier.
If you are worried that these small generators don’t have 50-amp or 30-amp plugs, this is where the parallel cable comes in and supplies you with a plug! It will be either a standard RV outlet or a twist-lock, like this one from Wen (paid link):
If you plan on using both A/C while boondocking, a couple of hundred watts of solar on your roof is probably a good idea. You can use an inverter charger (with power-assist or load-assist mode) to make up for A/C compressor surges and solar to refill your batteries.
The noise level of inverter generators is quite low and it is generally recommended if you would like to keep a friendly environment around your campground and or maintain your own sanity. At full (or rated) load, it means a noise level of 58-60 dB, and not higher.
Here is a noise rating of Honda inverter-generators:
| Model # | Noise Level @ Rated Load | Noise Level @ 1/4 Load |
|---|---|---|
| Super Quiet EU1000i (Gasoline, 900/1000-watts) | 50 dB | 42 dB |
| Super Quiet EU2200i (Gasoline, 1800/2200-watts) | 57 dB | 48 dB |
| Super Quiet EU2200i Camo (Gasoline, 1800/2200-watts) | 57 dB | 48 dB |
| Super Quiet EU2200i Companion (Gasoline, 1800/2200-watts) – 30A (L5-30R) | 57 dB | 48 dB |
| Super Quiet EB2200i (Gasoline, 1800/2200-watts) | 57 dB | 48 dB |
| Super Quiet EG2800i (Gasoline, 2500/2800-watts) | 67 dB | 62 dB |
| Super Quiet EB2800i (Gasoline, 2500/2800-watts) | 67 dB | 62 dB |
| Super Quiet EU3000iS (Gasoline, 2800/3300-watts) 30A (L5-30R) | 65 dB | 57 dB |
| Super Quiet EU7000iS (Gasoline, 5500/7000-watts), 30A (L5-30R) & 30A (L14-30R) | 58 dB | 52 dB |
And Yamaha inverter-generators:
| Model # | Noise Level @ Rated Load | Noise Level @ 1/4 Load |
|---|---|---|
| Yamaha EF2000iSv2 (Gasoline, 1600/2000-watts) | 61 dBA | 52 dBA |
| Yamaha EF2200iS (Gasoline, 1500/2200-watts) – RV ready (TT-30R) | 65 dBA | 57 dBA |
| Yamaha EF3000iSEB (Gasoline, 2800/3000-watts) – 30A (L5-30R) | 60 dBA | 53 dBA |
| Yamaha EF4500iSE (Gasoline, 4000/4500-watts) – 30A (L5-30R) | 60 dBA | 58 dBA |
| Yamaha EF6300iSDE (Gasoline, 5500/6300-watts) – 30A (L5-30R) | 64 dBA | 58 dBA |
Champion Inverter-Generators are getting very popular as well and for a good reason:
| Model # | Noise (Operational) |
| 100402 (Dual Fuel, Rated Gas 1600W/ LPG 1440W) | 53 dBA |
| 100306 (Gasoline, 1600/2000-watts) | 53 dBA |
| 200962 (Dual Fuel, Rated Gas 1850W/ LPG 1665W) | 53 dBA |
| 100889 (Gasoline, 1850/2500-watts) | 53 dBA |
| 100261 (RV Ready TT-30R, Wireless, Gasoline, 3100/3400-watts) | 59 dBA |
| 100371 (30A 120V L5-30R, Gasoline, 3300/4000-watts) | 64 dBA |
| 200991 (Dual Fuel – RV Ready, Rated Gas 3500W/ LPG 3150W) | 61 dBA |
| 100519 (30A 120V/240V L14-30R, Gasoline, 5000/6250-watts) | 61 dBA |
** Important! Specifications and product info are subject to change without notice.
** Disclaimer. Information in ElectricProblems.com specification tables is approximate and could contain an error. They also don’t include all available brands and products. Please consult the manufacturer for the latest and most accurate information.
Factory-installed generators
Generators, that are installed directly from the manufacturer are not inverter-based, but excellent soundproofing makes this type of investment also worthwhile. It is a permanent structure that gets connected to your gas tank for fuel.
These generators are made specifically for RV and should NOT be compared to regular, similar size contractor open-frame generators. Onan generators are also reasonably quiet and campground-friendly:
| Model # | Noise @ Half Load |
| Onan QG 2800 RM (Gasoline, 2800/2500-watts) | 71 dB |
| Onan QG 2500 RM LP (Propane, 2800/2500-watts) | 71 dB |
| Onan QG 2800(Gasoline, 2800/2500-watts) | 70 dB |
| Onan QG 2500 LP (Propane, 2800/2500-watts) | 70 dB |
| Onan QG 4000 (Gasoline, 4000/3600-watts) | 66 dB |
| Onan QG 3600 LP (Propane, 4000/3600-watts) | 66 dB |
| Onan QG 5500 (Gasoline, 5500-watts) | 67 dB |
| Onan QG 5500 LP (Propane, 5500-watts) | 67 dB |
| Onan QG 5500 EFI (Gasoline, 5500-watts) | 64 dB |
| Onan QG 7000 (Gasoline, 7000/6500-watts) | 67 dB |
| Onan QG 6500 LP (Propane, 7000/6500-watts) | 67 dB |
| Onan QG 7000 EFI (Gasoline, 7000-watts) | 64 dB |
| Onan QD 3200 (Diesel, 3200-watts) | 68 dB |
| Onan QD 5000 (Diesel, 5000-watts) | 68 dB |
| Onan QD 6000 (Diesel, 6000-watts) | 68 dB |
| Onan QD 8000 (Diesel, 8000-watts) | 68 dB |
| Onan QD 10000 (Diesel, 10000-watts) | 68 dB |
| Onan QD 12000 (Diesel, 12000-watts) | 68 dB |
** Important! Specifications and product info are subject to change without notice.
** Disclaimer. Information in ElectricProblems.com specification tables is approximate and could contain an error. They also don’t include all available brands and products. Please consult the manufacturer for the latest and most accurate information.
If A/C is your primary concern, a 50-amp coach with a 6,000-watt generator should be able to run both air conditioners and some other low-wattage appliances. It will be tight, this is why you need to watch your power consumption while using a generator.
Need to use a microwave, coffee maker, hair drier, or other high-wattage equipment? Turn one A/C off a few minutes. Good power management is what will allow you to actually enjoy basic (but important) life’s necessities and the beauty of nature at the same time:
Running A/C on a smaller generator
Start Capacitor
There have been some discussions about getting A/C to function on even somewhat smaller generators and if it is even possible. Some people say that installing a capacitor for a hard start should do the trick and give you a boost for starting your air conditioner on a smaller-size generator.
If your air conditioner only comes with a run capacitor, you can install a start capacitor parallel to that:
** Warning! Installing a capacitor is not a DYI project if you have no clue about what you are doing! Please consult a professional.
Load shedding
It works like this. Let’s say your 2 air conditioners consume about 12 amps each, but you also have an electric water heater that needs 10 amps and you need to charge your batteries (about 4 amps in float mode). If you combine all of these, you are easily going over 30 amps.
Your power management system will be shedding loads according to your priorities when you go over the available amperage amount. If you turn on your microwave and your electrical line is maxed out, the next available item on the list will be shredded.
After you are done with the microwave (for example), everything will be restored back to normal. This is a good way to prevent tripping breakers of either generator or shore power.
Here is one by Intellitec:
EMS needs to be installed by a professional since it is integrated with a breaker box and rewiring is required for all circuits that you want to control. Each desired item must be on its own circuit and removed from the breaker box before getting rerouted through EMS.
Check your RV documentation if you have a Power Management System (PMS) installed. It is commonly not intended for retail customers but is usually installed by the RV manufacturer.
This device sure beats flipping breakers all the time and will prevent both A/C units from starting at the same time. The only similar device that I found is EMS from Xantrex (paid link) and it can help you with power management in your RV:
Along with Xantrex Freedom PSW Inverter-Charger (paid link) and Xantrex Xanbus System Control Panel (SCP) (paid link), you get ultimate control over how your power is handled. For this setup to work with a generator, you will also need Automatic Generator Start (AGS).
Thermostat settings
It is very likely that your Dometic air conditioners come with a dual-zone thermostat! If you are just buying one, it is something to consider for excellent A/C management.
A Dometic thermostat consists of three parts that you have to purchase separately (some people don’t know that):
- Thermostat control panel (paid link).
- The thermostat itself (paid link).
- Thermostat cable (paid link).
What does this mean for your generator size? If two condensers will not be kicking in at the same time, the exclusively large generator is not required at all (you can simply add up a surge rating of 1 A/C to running watts of the other).
Take advantage of this tool and you will have no problem running two A/Cs at the same time. Here are some instructions on how to program it, starting on page 16.
Soft starters
The last, but not the least important tool in keeping your RV cool during the hot summer days is RV Soft Starter. This neat little gadget wires directly to your A/C and its whole function is to absorb startup surges and also high current demand when the condenser kicks in.
Here are some soft starters for you (sorry, that’s all I found and if I find more, I will add):
| Model | Wiring Diagrams | UL-listed | Current Reduction |
| Soft Start RV (paid link) | YES | NO | 70% |
| EasyStart 364 (paid link) | YES | YES | 75% |
** Important! Specifications and product info are subject to change without notice.
** Disclaimer. Information in ElectricProblems.com specification tables is approximate and could contain an error. They also don’t include all available brands and products. Please consult the manufacturer for the latest and most accurate information.
Adding a Hybrid inverter-charger with power support (or assist) mode that can support your load when needed is another option that I will discuss below. It’s extremely powerful and many RVers are turning more to this type of setup:
Inverter-charger with Power Assist
The function of an automatic transfer switch is to provide a safe and reliable way to move loads between power sources. When a normal power supply fails to deliver (just like in our case with A/C startup surge), the next available power backup source (like batteries), will be used to provide the circuit with power.
This means that circuit will NOT be overloaded and breakers will NOT trip. Inverter-chargers come in many shapes and sizes, but they have one important thing in common:
Built-in transfer switch!
When the inverter charger detects A/C (like shore power or generator), it will act as a pass-through, and when no or low A/C power is detected, it will switch to DC mode and start converting it for your 120-volt devices. Few of those models offer power assist mode.
Victron (Power Assist)
Here are some models from Victron:
| Model # | Load Sharing |
|---|---|
| Power Assist | |
| MultiPlus Compact, 2000/4000-watts (24V) | Power Assist |
| Multi-Plus, 3000/6000-watts (12V) | Power Assist |
| Multi-Plus, 3000/6000-watts (12V, UL-Certified**) | Power Assist |
| Multi-Plus, 3000/6000-watts (24V) | Power Assist |
| Multi-Plus, 3000/6000-watts (24V, UL-Certified**) | Power Assist |
| Multi-Plus II, 3000/5500-watts (2 x 120V *, 12V) | L1 only * |
| Multi-Plus II, 3000/5500-watts (120V ONLY, 48V) | Power Assist |
| Quattro, 3000/6000-watts (48V) | Power Assist |
| Quattro, 5000/10000-watts (12V) | Power Assist |
| Quattro, 5000/10000-watts (24V) | Power Assist |
| Quattro, 5000/10000-watts (48V) | Power Assist |
| Quattro, 10000/20000-watts (48V) | Power Assist |
* Note. Power assist feature on one leg only (L1).
** Important! Specifications and product info are subject to change without notice.
** Disclaimer. Information in ElectricProblems.com specification tables is approximate and could contain an error. They also don’t include all available brands and products. Please consult the manufacturer for the latest and most accurate information.
Magnum (Load Support)
Magnum Energy offers hybrid models that will use batteries to give you more power when needed:
| Model # | Load Sharing |
|---|---|
| MSH-M Hybrid, 3000/3900-watts (12V) | Load Support |
| MSH-M Hybrid, 4000/5800-watts (24V) | Load Support |
| MSH-M Hybrid, 4000/5800-watts (24V, w/Dual AC Inputs) | Load Support |
| Hybrid MSH-M Hybrid, 3000/3500-watts (12V) | Load Support |
** Important! Specifications and product info are subject to change without notice.
** Disclaimer. Information in ElectricProblems.com specification tables is approximate and could contain an error. They also don’t include all available brands and products. Please consult the manufacturer for the latest and most accurate information.
Go Power! (Power Sharing)
Another inverter-charger with the power-assist mode is Go Power, but it is getting a lot of complaints lately:
| Model # | Load Sharing |
|---|---|
| GP-IC-2000-12, 2000/4000-watts (12V) | Power Sharing |
| GP-IC-3000-12, 3000/4800-watts (12V) | Power Sharing |
** Important! Specifications and product info are subject to change without notice.
** Disclaimer. Information in ElectricProblems.com specification tables is approximate and could contain an error. They also don’t include all available brands and products. Please consult the manufacturer for the latest and most accurate information.
Hope this article clarifies what options you have for running A/C on your generator.
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