Why won't Yamaha EF6300iSDE generator start A/C on 240 volt?

If you look at the wiring diagram in the Owner's Manual you will see that there are two inverters (part of Control Unit) that are in fact connected in series or parallel via the Voltage Select Switch. In 120 volt mode you have double the current available than when in 240 volt mode. In 240 volt mode, you have the equivalent of two separate 3150 peak, 2750 running VA generators that happen to have a synchronized output. Only one of these two generators can be applied to an individual air conditioner. However, IMO, you should be able to run two of your air conditioners in 240 volt mode, but you have to do the same things that those of us with smaller generators have to do: Water heater on propane, fridge on propane, possibly switch power converter off, and possibly add start capacitor to the air conditioners. You're also susceptible to performance loss at higher elevations.

belfert wrote:
I have a Yamaha EF6300iSDE inverter generator. I have 50 amp service in my RV. When I plug into the 120/240 outlet none of my three rooftop A/C units will start. The generator will show 50% on the power graph and the overload light comes on.

Now, if I plug into the 30 amp 120 volt outlet with a 30 amp to 50 amp converter I can start any of the A/C units. In fact, I can run three rooftops on the 30 amp plug with the compressor running on all three.

Why would the rooftops not work when in 240 volt mode with a 50 amp connection? Is 26 amps on one leg just not enough to start a rooftop even when it is 75 degrees outside?

26A is the SURGE current not the RUN current which is 22.9A per specs when running 240V.

SPECS HERE

"45.8 amps /52.5 amps @120V; 22.9 amps/26.3 amps @ 240V"

By the way, the 22.9A is 2748W and surge 26.3A is 3156W at 120V which IS what you are getting to EACH 120V "leg".

I suspect that there is TWO 120V inverters in the unit not one, the inverters are "synced" and connected in "series" in order to produce 240V. Not sure if there is a 120V only mode but if there is then the TWO 120V inverters would be "paralleled" providing more power on the 30A 120V outlet..

If you have ANYTHING else running I doubt that your gen will be able to handle THREE A/C units.

A 13K A/C unit will have run current of 13A, surge current can easily top 25A. A 15K A/C can have a run current of 15A and surge will easily top 29A.

Make sure your fridge is on gas, water heater is set to gas only (if equipped with electric heating element), CONVERTER is turned of and no other item is plugged in or running.

Do you have 120 volts ANYWHERE in the RV when connected to that 50 amps? The AC units(compressor) has NO WAY to know what the supply is. Do the AC fans run? Do the compressors try to start? Doug

Artum Snowbird wrote:
I see your point exactly. It almost seems that either leg is limited to 26 Amps in the 50A setup, but you can get 30 amps out of one leg only without overloading the generator.

This.

Artum Snowbird wrote:
I see your point exactly. It almost seems that either leg is limited to 26 Amps in the 50A setup, but you can get 30 amps out of one leg only without overloading the generator.

There is a switch to make the generator 120 volt only or 120/240 volt. I set it to 120 volt only when I am using just the 30 amp 120 volt receptacle. The only thing in the vehicle drawing power besides the A/C is the inverter battery charger, but it wasn't charging at the time anyhow.

This generator is an inverter generator so presumably it is the inverter that switches between 120/204 and 120 only. It isn't like a traditional generator that has two legs on the the generator head to do 240 volt.

I see your point exactly. It almost seems that either leg is limited to 26 Amps in the 50A setup, but you can get 30 amps out of one leg only without overloading the generator.

I don't know whether if will make any difference or not, but you could try running the A/C units to give them a little prestart on the 30A plug then do a quick switch on your cable and a quick start on your A/C units and plug into the 50A setup.

You could also try shutting down the feed to everything else except your a/c's so you are not using any power for your converter, fridge (on auto) or other load grabbers and see if that makes a difference.

Sweet Old Bill wrote:
Someone will be along shortly with a better comment, but the short version is - - - your camper does not run on 240v. The 50amp connection for the camper is two 120v legs. Everything on AC circuits is 120v.

Hope all is well and no damage done.

A properly designed 50 amp RV connection should be 240 volts across the two hots! Technically, you could supply each side of the outlet from the same 120 volt feed as most RVs don't have 240 volt appliances, but what happens when someone has a 240 volt appliance and expects 240 volt? I believe it would be a code violation to wire a 50 amp receptacle and not have it be 240 volt with a ground and a neutral.

Now, a 30 amp RV connection should NEVER be 240 volt. Plenty of electricians have wired them at 240 volt and fried the electrical stuff in the RV.

As already stated, I was NOT running 240 volt into 110 volt appliances.

Yes, I understand that a 50 amp connection is two 120 volt legs. The generator has a L14-30 receptacle so it has two hots, a neutral, and a ground. I am using a proper adapter to go from a L14-30 receptacle to a 50 amp RV receptacle. I was NOT running 240 volts into appliances designed for 120 volt. The issue appears to be that when a compressor starts it pulls too much juice.

My real question I guess is how do I get all 5,500 watts out of the generator considering it won't start air conditioners using the 120/240 volt receptacle? There is a 120 volt 30 amp receptacle, but that is only rated for 3,600 watts. I have used the 30 amp receptacle and everything works fine.

Hopefully you didn't damage anything. Does your owner's manual discuss the usage of its 240v outlet?

Someone will be along shortly with a better comment, but the short version is - - - your camper does not run on 240v. The 50amp connection for the camper is two 120v legs. Everything on AC circuits is 120v.

Hope all is well and no damage done.