running rooftop a/c while underway

[LarryD]

the coach can get quite warm while underway. Im wondering if anyone has moved the a/c circuit over to the inverter to power it while driving. The alternators should be able to keep up with at least one a/c. any thoughts?

[halfprice]

Just run the generator

Jerry

[Raeburn2000]

We always run the generator if we need AC on the road. The inverter doesn’t have enough instantaneous supply to handle the compressor power surge when the AC first starts. You would risk wrecking the inverter.

[Bob Denman]

Originally Posted by halfprice

Just run the generator
Jerry

Yup!
The inverter probably doesn't have the capacity to run the A/C...

[LarryD]

without a/c I have a load 208w. Surge when I start A/C jumps to 1785watts and then settles down to 1648watts. Means the a/c surge is 1578w and running load is 1440w. Both of these are well within the capability of the inverter to support. Our dual alternators are either 175/157amp or 240/157 amp units. Thats 2100/1884 watts or 2880/1884 watts. More than enough to run an a/c and sustain the batteries. Technically this is all possible. If no one else has done it I'll give it a shot and report back.

[halfprice]

Originally Posted by LarryD

without a/c I have a load 208w. Surge when I start A/C jumps to 1785watts and then settles down to 1648watts. Means the a/c surge is 1578w and running load is 1440w. Both of these are well within the capability of the inverter to support. Our dual alternators are either 175/157amp or 240/157 amp units. Thats 2100/1884 watts or 2880/1884 watts. More than enough to run an a/c and sustain the batteries. Technically this is all possible. If no one else has done it I'll give it a shot and report back.

But why???? That's what's the gen is for. Are you trying to save the .5 gal of gas to run gen for an hour

Jerry

[Bob Denman]

If your A/C unit's running "pull" is a steady 1440, and you're (at best!) putting back in 397: you will drain those batteries...
Run the generator.

[LarryD]

how'd you get 397?

[LarryD]

has nothing to do with saving fuel. Motor is already running, gennie is not. Why put hors on it when its not needed. Also, for more context, I want to be able to run an a/c while boondocked on the beach. Getting the a/c to run off of the inverter is another step in that direction (along with adding more batteries and solar)

[ducksface]

I could run my ac from my inverter. I set it up that way. I was going to do away with the generator, sell the generator, and have enough from the sale to put on dual Goodall 2,000w alternators. I'd add a large amount of storage where the generator had been.
My airconditioning power came through the batteries no matter engine or shore or generator.

It was a ridiculous exercise in reinventing the wheel.
I have since had it changed so everything in the coach runs on the inverter except the airconditoning. I changed it back because one of my batteries went bad. This entirely, 100% kept me from having airconditioning until I replaced the bad battery.

My generator ran almost every mile of my recent 5,900 mile trip.
At 60mph(I'm really more of a 75mph driver)
My generator gets 120mpg.
The faster you drive the better the mpg.

I was wrong about the battery pass through.
I was doing this because the plan was to add twelve 6v batteries I had sitting here.
That was also wrong.

My setup would have allowed me to run the ac while going down the road and not need the generator.
But
My inverter was already a 3,000w unit with a 4,500w surge ability and a built in 350a charger. It has the ability to piggyback to 6,000.
You'll need one. They're $1,800...each.


And
Solar has ZERO value if your generator or engine or shore power is supplying power.

[Axis25.2]

Originally Posted by LarryD

has nothing to do with saving fuel. Motor is already running, gennie is not. Why put hors on it when its not needed. Also, for more context, I want to be able to run an a/c while boondocked on the beach. Getting the a/c to run off of the inverter is another step in that direction (along with adding more batteries and solar)

One of my favorite latest add-ons... Now, the AC is much quieter (can hardly hear the compressor kick on) and runs off 1 honda 2000 generator. 20 min easy install and it may run on your inverter. I have no idea what inverter you have. But, if it can handle the new 12amp initial AC compressor pull from the soft-start, you're golden... JMHO

https://www.amazon.com/Hutch-Mountai...s%2C200&sr=8-9

[halfprice]

Originally Posted by LarryD

has nothing to do with saving fuel. Motor is already running, gennie is not. Why put hors on it when its not needed. Also, for more context, I want to be able to run an a/c while boondocked on the beach. Getting the a/c to run off of the inverter is another step in that direction (along with adding more batteries and solar)

Generators want to be run. Inactivity is the worst thing for them. But I see what you're trying to do. Good luck with it

Jerry

[Pete'sMH]

Originally Posted by halfprice

But why???? That's what's the gen is for. Are you trying to save the .5 gal of gas to run gen for an hour

Jerry

My thought as well. Why?! The added load on the alternators will use gas as well. Maybe not quite as much but again, why?

[16ACE27]

Originally Posted by Bob Denman

If your A/C unit's running "pull" is a steady 1440 Watts, and you're (at best!) putting back in 397 Amps : you will NOT drain those batteries...
Run the generator.

Units, Bob.

FTFY

[Bob Denman]

Originally Posted by LarryD

how'd you get 397?

I was trying to take the dual alternator out puts from this post...

Originally Posted by LarryD

without a/c I have a load 208w. Surge when I start A/C jumps to 1785watts and then settles down to 1648watts. Means the a/c surge is 1578w and running load is 1440w. Both of these are well within the capability of the inverter to support. Our dual alternators are either 175/157amp or 240/157 amp units. Thats 2100/1884 watts or 2880/1884 watts. More than enough to run an a/c and sustain the batteries. Technically this is all possible. If no one else has done it I'll give it a shot and report back.

I took the higher total in order to give you the benefit of doubt...

But if there's something wonky about my logic: please tell me!

[LarryD]

Those are the amps. to compare apples to apples use watts. 2880 watts at max would more than cover the load and charge batteries. Really the question becomes at what speed (rpm) are the alternators providing that and is it still efficient for the main engine to carry that extra load. Folks keep asking why but are missing the whole point. It's all there, should work well and even be a more efficient use, saving wear and tear on the gennie. So, WHY NOT?

[Bob Denman]

That was a brain-fart from me...
I didn't catch "amps" in there...

[TurnerFam]

you're overthinking the thought of using the inverter(s)/batteries to power a HUGE 120v draw from a large appliance, just as much as you're overthinking the 'concern' of putting 'more' hours on your generator, which is designed to already to EXACTLY what you are wanting: power the air conditioner. It's already there, so why spend MORE money, time, and effort, on 'Solar', 'Batteries', and other needs that AREN'T already there.

You are going to spend a LOT LOT LOT more than just a little fuel in the generator. They are actually VERY efficient in what they do.

[LarryD]

I think I've confused folks. Running the a/c off the inverter while running main engine wont cost anything. Just have to move the a/c circuit onto the inverter.

the solar/batteries I mentioned is my desire to be able to boondock without shore power. Sorry about that.

[Pete'sMH]

Well if you want to do it you should just do it. It doesn’t have to make sense to any of the rest of us.