Marathon Electrical

I think I finally got the electrical sources all sorted out, but let me know if I'm off base.

The two 4K trace inverters only operate certain electrical devices. They include microwave, refrigerator, TV's, VCR, Sat Dish and electrical outlets. Everything else requires shore power or generator. I was under the impression that an A/C could be run off the inverters, but no can do. At least now I know if I lose the inverters, I still have the cruise airs and heat pumps, kick heaters, hot water heater, all the other appliances and of course the house heat and hot water off the webasco.

Seems like each converter does something different. One thing is for certain in these all electric buses, managing the power is a must. 50 amp shore power really doesn't get you much, especially if your using 2 A/C's. The article on the other board about reducing the bulk charge time was great and I set mine up to only go 20 minutes on shore power. When dry camping I will go back to the full 2 hrs.

Another good tip was the changing of the inverters shore power to 15 amps each when on 30 amp. I guess some do this automatically, but mine is an older one.

Taking a shakedown cruise this weekend to Nashville just to make sure all the bugs are worked out prior to POG.;)

Tom,

You are correct about each converter doing things their way. I am still trying to make sure I have a total understanding of how my inverters are set up, but I think there are some things all of our coaches have in common.

I suspect your inverter run appliances and devices will either be located together in your panel or they will have some way to identify those that can and cannot be operated from an inverter. On my Liberty inverter powered devices have a red band around the breaker.

I'm surprised about your comment that you can't use 50 amp without power management. Your AC units should only draw 13 running amps so with all three running you are probably pulling 26 amps on one leg and 13 on another, leaving conservatively 14 remaining on one leg and 27 on the other (I used 80% of the circuit breaker rating). Fifty amp is NOT like 30 amp. It is two 120V 50 amp legs as opposed to one 30 amp 120V leg. Huge difference.

I think I am right in saying this and if I am wrong I hope someone corrects me. My coach, and possible all other inverter coaches have one weak spot. If you have a failure of the current sensing circuit or the relay that allows shore or generator power to go straight to the devices or appliances you will not be able to operate those appliances or devices even though you have power available to the coach. In an emergency you will have to manually connect the electric supply wires (at the inverter) to the output wires.

I am surprised with two 4000 watt inverters the AC units cannot be powered. I yield to a Marathon owner to address that. That is a lot of inverter power to run a refrigerator and microwave. That suggests Marathon expected you to run the generator while driving down the road and that doesn't make sense.

Jon,

Thanks for the input.. I haven't put it to the test yet on 50 amp, I was kind of basing my assumptions on the books, so hopefully it will be as you suggest. One really good thing is the system will automatically disconnect the second leg in the event of an overload and allow me to reduce the power requirements and then hit the panel reset button.

I had the same thought as you, two 4K inverters is a lot of juice for just the items I mentioned. There may be a switch of some kind while the engine is running to allow the A/C's to run off the inverter. I tried an A/C while not being plugged in and none of the panels would turn on (no power). I'll have a better understanding after using it this weekend.

You bring up another good point, if an inverter goes south, will I really still have power to the A/C's, etc. Maybe another Marathon owner knows the answer.

This is a call to all attending the POG rally. What we need at one of our BS sessions is someone or perhaps more than one person to explain the logic behind the electrical circuits in our coaches. I am somewhat familiar with my inverter coach, and very knowledgable about my 87 Liberty.

I have to believe that even though the converters have their own way of doing things, there is a certain consistency to the logic behind the system designs.

None of this is important until one of us experiences a system failure, and then having a basic understanding will go a long way towards working around the failure, or having a miserable trip.

Tom & Jon,
I posted on the other site, my 99 will run 2 of the 3 Cruise airs on the inverter. The only thing that you must start the gen or be plugged into 50 amps is the cook top. I am very behind on the inverter thing and just keep mine on the preset factory settings with the auto start turned off. Not the best way to use what I have but due to lack of knowledge will keep me safe for now.
Kevin
99 Marathon XL

Kevin,
You are correct, the inverters will run the A/C's. What I didn't realize was you set up the 3 A/C control panels to to your desired temperature and then while driving you can select 1 or 2 A/C's as needed from the buttons on the dash control panel. Without those buttons in the on position, the A/C's don't have any power. Great feature while driving if you need to supplement the dash A/C.;)