Running 1 Roof Air on Inverter While Driving

Topic: Running 1 Roof Air on Inverter While Driving (Read 2158 times) previous topic - next topic

Running 1 Roof Air on Inverter While Driving

September 05, 2015, 10:06:22 pm

Here is a new thread to document my testing and proof of concept.

I tried my Xantrex PROWattSW 2000 inverter, and while a great inverter, it just can't handle high surge loads, so no go.

So after a lot of research I ordered this AIMS Pure Sine 4000 watt unit from Amazon and installed it today:

AIMS Pure Sine 4000 Watt Inverter

This inverter/charger has 7 battery type charge settings, has a 100 amp charger and you can adjust the charge rate from 0% to 100%. I liked the customization available.

It has a rating of 4000 watts continuous and 12000 watts peak. This is not a lightweight inverter, it weighs 72 pounds.

Since it does not have built in branch breakers, I installed a 2 circuit branch breaker box, with 2 - 20 amp breakers, one for the front roof air, one for the new duplex outlet I installed in the kitchen. I fed the inverter with a 30 amp breaker in the coach main panel. This required running a new 10 gauge supply wire to the inverter from the main breaker box, and 2 - 12 gauge wires from the inverter sub-box back to the coach main breaker box, one for the front roof air, one for the new duplex kitchen outlet.

After wiring was complete, I fired it up and everything functioned as it should.

Now the big test, could this inverter start and run the roof air. Yes, it started and ran no problem. The running amps was approx 170. I did some testing with my son holding the engine RPM at approx 1700 to simulate cruising speed and the with the headlights on the alternator was supplying approx 200 amps.

I'll post additional info after I do some actual road testing

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Re: Running 1 Roof Air on Inverter While Driving

Reply #1 – September 05, 2015, 10:55:02 pm

Yes, good catch, fixed it - 12 gauge wires - for 20 amp circuits.

The 200 amps were measured on the alternator wire to the isolator while the engine was held at 1700 RPM.

Re: Running 1 Roof Air on Inverter While Driving

Reply #2 – September 05, 2015, 11:54:33 pm

Nice work Peter. Looking forward to how this works out. Please keep us informed.

see ya
ken

Re: Running 1 Roof Air on Inverter While Driving

Reply #3 – September 06, 2015, 06:00:19 am

Great write up on this project. Did you upgrade the alternator too?

Re: Running 1 Roof Air on Inverter While Driving

Reply #4 – September 06, 2015, 07:04:40 am

Wow!

Peter I know a lot of folks would love to use one AC and no generator when driving down the road; however, seems like a lot of draw from the batteries when you stop for breaks and meals. Great idea and you appear to be very knowledgeable. Will be really interested on your follow up as to how all this works. DAN

Re: Running 1 Roof Air on Inverter While Driving

Reply #5 – September 06, 2015, 07:55:06 am

5 or 6 years ago Foretravel offered this as an option on a new coach.
Dont remember if it was just the Phenix.

Re: Running 1 Roof Air on Inverter While Driving

Reply #6 – September 06, 2015, 09:18:03 am

200 Amps requires 3/0 copper wire. Does the alternator have that size of wire. You can get by with smaller but with a continuous load it will get warm.

Re: Running 1 Roof Air on Inverter While Driving

Reply #7 – September 06, 2015, 09:29:33 am

turbojack:

Yes, first I wanted to see if I could find an inverter with enough surge capacity to overcome the locked rotor amps of the A/C compressor.

My plans now are to beef up the 12V charging system with a 40SI alternator, larger isolator, and as you mentioned, heavier cabling to the isolator and to the batteries.

Re: Running 1 Roof Air on Inverter While Driving

Reply #8 – September 06, 2015, 09:32:18 am

I have a 2800W outback inverter, and was planning on running the front AC off it once I upgrade to an atwood air command. I can easily run the dometic penguin off my honda eu2000i while parked, so I'm sure the outback will manage. bigger brushless alternator in my future! glad to see it worked for you, pretty much how I expected it would.

Re: Running 1 Roof Air on Inverter While Driving

Reply #9 – September 06, 2015, 09:57:23 am

Quote from: prfleming – September 06, 2015, 09:29:33 am

My plans now are to beef up the 12V charging system with a 40SI alternator, larger isolator, and as you mentioned, heavier cabling to the isolator and to the batteries.

With that kind of current, it make make sense to ditch the isolator install a manual switch or some type of solid connection like a solenoid (combiner). The diode isolators sucks up power as current passes through it, and you are using lots of juice now.

Re: Running 1 Roof Air on Inverter While Driving

Reply #10 – September 06, 2015, 10:10:52 am

Yes, the isolator gets pretty hot - wasted power. I am also considering wiring the alternator directly to the house batteries as this is where the large current is required, and use a smart combiner to connect to the chassis battery. Here is one my son used in his Lincoln to add a 2nd battery for the sub-woofer amp. It has worked well now for almost a year.

Cole Hersee 48530 Smart Battery Isolator 200A

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Re: Running 1 Roof Air on Inverter While Driving

Reply #11 – September 06, 2015, 10:20:36 am

I installed a yandina in place of the isolator. Combiner 160 Sheet

If you direct wire to house batteries, I'd have wire in a switch or make up a mechanical jumper just in case the combiners fail. You can just wiring it together manually in 1 minute if needed.

Re: Running 1 Roof Air on Inverter While Driving

Reply #12 – September 06, 2015, 11:11:54 am

How about a second alternator where the stock AC compressor is now? Might keep alternator temps down and a failure would not be disabling. Wire directly to house batteries? An alternator running close to capacity will have a shorter life. Inverter should have 10-20x AC startup load for long life.

Might try an old AC for RVs but using butane/propane instead for an experiment. Has been done on a lot of cars. Should drop the current requirement way down, especially for startup.

A to Z propane/butane conversion at Possum Living: Possum Living: Propane Refrigerant for Automotive Air Conditioning

May not be legal in all states.

Pierce

Re: Running 1 Roof Air on Inverter While Driving

Reply #13 – September 18, 2015, 06:03:26 pm

I dunno, it almost seems like less effort to install/repair the over the road chassis a/c. Ours works *very* well and will cool us up front until about 87-90F outside. It is a very clever option though. You could also install a later model a/c unit that pulls less amps.

Re: Running 1 Roof Air on Inverter While Driving

Reply #14 – September 18, 2015, 06:13:23 pm

I don't mean to be a smartass.....but all this labor and expenditure to save 1/2 gal of diesel an hr while your motorhome is getting 7mpg? I need a beer.

Re: Running 1 Roof Air on Inverter While Driving

Reply #15 – September 18, 2015, 08:04:29 pm

Ah, you can't help it Twig

For us, it isn't about saving the half gallon an hour of Diesel, but being able to run the A/C for short periods off of the inverter. Say while stopping for lunch... or while plugged into a buddies 15amp circuit while driveway camping and the starting current pops his breaker. Having the soft start set up and an inverter circuit that can be switched to supply one A/C would be helpful. Still, we already have the 3000 watt inverter and the large battery bank (4 8D's), so a soft start set up would be a minimal extra expense and helpful in other ways. Just my thoughts...
Don

Quote from: Twig – September 18, 2015, 06:13:23 pm

I don't mean to be a smartass.....but all this labor and expenditure to save 1/2 gal of diesel an hr while your motorhome is getting 7mpg? I need a beer.

Re: Running 1 Roof Air on Inverter While Driving

Reply #16 – September 18, 2015, 08:11:03 pm

I like prfleming's thinking, why run and put hours on your generator, when you can use a fraction of the power of your main engine to run your ac. I doubt that the ac would decrease the mpg that much, and if you had solar to augment the alternator, maybe no decrease. Even at $2.00 a gallon, your gen will cost you a 6 pack or two, a day to run.

Jim

Re: Running 1 Roof Air on Inverter While Driving

Reply #17 – September 19, 2015, 06:34:02 am

The new coaches are set up for it so I am sure ours can too. I think there is enough room on my coach to put a bigger alternator. The issue would be lining up the belts and increasingt He wire and a new isolator. I do not think it would be a hard upgrade and I have been thinking of doing it too.

Re: Running 1 Roof Air on Inverter While Driving

Reply #18 – September 19, 2015, 06:57:31 am

Something like this might support the energy consumption
http://delcoremy.com/Documents/Brochures/Delco-Remy-55SI-Brochure-5-12.aspx

Re: Running 1 Roof Air on Inverter While Driving

Reply #19 – September 19, 2015, 08:21:37 am

Fixing the Dash A/C, which I think the original reason for this idea, is probably cheaper and more effective.

Re: Running 1 Roof Air on Inverter While Driving

Reply #20 – September 19, 2015, 11:04:44 am

On my coach the dash ac will cool driver and co-pilot only. If you are carrying anyone behind the front area in hot weather, you pretty well must have overhead ac.

Jim

Re: Running 1 Roof Air on Inverter While Driving

Reply #21 – September 19, 2015, 11:29:47 am

Too bad it only comes in pad mount (though I am sure that could be worked around), and especially too bad it is $2173! (lists for over $3K). Still, 430 Amps... wow!
8600529 by DELCO REMY - ALTERNATOR 55SI 12V
Way more than necessary, but I like overkill! I will keep my eye open for a super ebay deal on a 250 to 320 amp or thereabouts. If I can get it cheap enough... I will start with the soft start set up and figure out the need vs our puny 160 amp Leece Neville.
Don

Quote from: stump – September 19, 2015, 06:57:31 am

Something like this might support the energy consumption
http://delcoremy.com/Documents/Brochures/Delco-Remy-55SI-Brochure-5-12.aspx

Re: Running 1 Roof Air on Inverter While Driving

Reply #22 – September 20, 2015, 10:08:44 am

I just run my generator- keeps all 3 airs and the entire coach comfortable.

Re: Running 1 Roof Air on Inverter While Driving

Reply #23 – September 20, 2015, 10:22:34 am

Quote from: Don & Tys (AKA acousticart) – September 19, 2015, 11:29:47 am

Too bad it only comes in pad mount (though I am sure that could be worked around), and especially too bad it is $2173! (lists for over $3K). Still, 430 Amps... wow!
8600529 by DELCO REMY - ALTERNATOR 55SI 12V
Way more than necessary, but I like overkill! I will keep my eye open for a super ebay deal on a 250 to 320 amp or thereabouts. If I can get it cheap enough... I will start with the soft start set up and figure out the need vs our puny 160 amp Leece Neville.
Don

Don this one would give you 320 amps and is available in 3 mounting styles
http://delcoremy.com/Alternator-Models/40SI-High-Output-Brushless-Heavy-Duty-Alternator.aspx

Re: Running 1 Roof Air on Inverter While Driving

Reply #24 – September 20, 2015, 10:25:23 am

Quote from: erniee – September 20, 2015, 10:08:44 am

I just run my generator- keeps all 3 airs and the entire coach comfortable.

Ernie, I do the same thing and am almost at 5000 hours on my generator. I think for the odd times that you do not need all three but just one unit, a engine driven way of running it would be very nice.

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