AC off battery

[CSD11]

I'm sure this has been discussed before, but I am new to the forum and was having trouble with the search function.

We recently purchased a Coachmen Entourage. The only thing we didn't like about it was that it had a propane generator. I would like to find a way to run one of the AC units while traveling down the road w/o running the generator.

Currently it is equipped with 2000w inverter, 2 house batteries (160-200ah total) and a 220amp alternator specific for house (another 150amp alt for chassis).

I assume this is possible with some alterations/upgrades.

What would I need?

3000w inverter
soft start for AC
more ah for batteries (lithium batteries probably best way to accomplish)

What am I missing?

Thanks,
Chris

[Tony Ramirez]

Most likely at a minimum: 3000W inverter, Soft Start for AC unit wishing to run, Rewiring AC unit to run off Inverter. Then, Lithium Batts w MORE AHs, a DC2DC Charger so you don't fry your alternator, & a decent solar setup to supplement you alternator.

It's possible, but there's a lot involved to do it right. Then you have to figure if the upfront cost will offset the savings in your propane.

I'm going thru that thought process now. Haven't pulled the trigger yet.

[d23haynes57]

With the separate alternator you should be good t carry one AC unit while driving. You can have the AC wired to the inverter but then that circuit would be limited from running other appliances with the AC. A transfer switch could be installed for the AC or a separate dedicated inverter. You could also upgrade the inverter to a 3,000 watt. You should also consider more battery and a larger battery charger to maximize use of the generator. I would go for a 3000 watt inverter with a 150 amp charge section and 600 to 900 A/H of battery. This will allow you to even run one of the AC through the night without generator. If you wish, I could do the engineering for you to make this work.
P-Mail dennis-vw-service@outlook.com

[CSD11]

Forgot to mention that we currently have a 200w solar panel and I believe its expandable upto 600w.

We generally don't boondock, so this would mainly be for when driving down the road during the summer months.

[followingsea]

Originally Posted by CSD11

..... The only thing we didn't like about it was that it had a propane generator. I would like to find a way to run one of the AC units while traveling down the road w/o running the generator.

....

...

Thanks,
Chris

Welcome to the forum.

My MH is designed to run the roof A/C off the propane generator when not connected to the grid.

My dash air did not work when I bought the MH so I use the generator to run the roof A/C when going down the road.

Running A/C off batteries or alternators is a terrible idea. Why would you do it?

[Tony Ramirez]

Originally Posted by CSD11

Forgot to mention that we currently have a 200w solar panel and I believe its expandable upto 600w.

We generally don't boondock, so this would mainly be for when driving down the road during the summer months.

I missed the 2nd alternator fact, sorry. So the cost of the 3000W inverter & more batts, plus the rewire(which I could do myself). That's what I'm trying to decide, how much would I really save for those times vs just run the gen. Plus, I have to "exercise" the gen at least monthly anyway.

[CSD11]

Not sure running AC off batteries/alternator is a bad idea, maybe you can elaborate on why it is.

I think putting a propane generator on a diesel motorhome is a bad idea. Its my understanding that the generator can run approx 16-18hrs on a tank of propane. It not uncommon for us to do 14-15hr day driving. This would mean I would have to stop for propane before our final destination which is not a big deal if you are near truck stops like your pilots, flying Js, etc but if your not it makes it a bit more difficult.

If I can have a battery system, my fuel stops are a lot easier.

[Tony Ramirez]

CDS11, you're right about the propane gen in a diesel motorhome being a bad idea. That said, you probably aren't going to need the roof AC the WHOLE 14-15hr day of driving. I usually just need mine towards the later afternoon in the summer. MAYBE, early afternoon on the Really hot days. Plus, when it is HOT, I like to get to a hook up campground by 6-7pm latest, so maybe 4hrs gen time. You can probably get away with 4-5 days between propane fill ups.

[d23haynes57]

What size is your genny? I'm thinking it will need ~.5 gallon/hour. Probably the issue is not the cost of the propane but availability and frequency to fill. If you have a propane genny you probably also have a water heater and furnace that can inhale it also.
I'm toying with this idea for my Nimbus. From being at campgrounds with limited power I know that once the rig is cooled, one AC will keep it cool overnight. It would be nice to have overnight AC without anyone having to hear or smell the generator.

[twinboat]

I disagree.

[Tony Ramirez]

Originally Posted by d23haynes57

What size is your genny? I'm thinking it will need ~.5 gallon/hour. Probably the issue is not the cost of the propane but availability and frequency to fill. If you have a propane genny you probably also have a water heater and furnace that can inhale it also.
I'm toying with this idea for my Nimbus. From being at campgrounds with limited power I know that once the rig is cooled, one AC will keep it cool overnight. It would be nice to have overnight AC without anyone having to hear or smell the generator.

If you do it, you want to look at the Victron MultiPlus II. From their Data Sheet description, "PowerAssist takes the principle of PowerControl to a further dimension. Where peak power is so often required only for a limited period, the MultiPlus-II will compensate insufficient generator, shore or grid power with power from the battery. When the load reduces, the spare power is used to recharge the battery (available on L1 input only).
Or the MultiPlus II 2x120 for 50Amp rigs

The only downside is they are rated @ 120Max charging, you mentioned 150A charge.

[d23haynes57]

Originally Posted by Tony Ramirez

If you do it, you want to look at the Victron MultiPlus II. From their Data Sheet description, "PowerAssist takes the principle of PowerControl to a further dimension. Where peak power is so often required only for a limited period, the MultiPlus-II will compensate insufficient generator, shore or grid power with power from the battery. When the load reduces, the spare power is used to recharge the battery (available on L1 input only).
Or the MultiPlus II 2x120 for 50Amp rigs

The only downside is they are rated @ 120Max charging, you mentioned 150A charge.

My Xantrex does the same thing with much less complication.
FREEDOM XC PRO Marine 3000
3000W, 150A
PN: 818-3015
I went the Marine version as it is installed in a basement compartment. Probably overkill.
I also have the remote display. It replaced to original Outback 2,000-watt 70 Amp charger. Direct replacement as battery cable was already 3/0 and 110 in/out was 30-amp 10-gauge circuit. The power share makes that work.

[Paul_D]

The RV comes with an auxiliary alternator rated at 220 Amps for the house.

If the cabling to the inverter/battery bank is properly sized and protected, the aux alternator could handle the AC unit while driving. Depends on the other 12 V DC loads (battery charger, refrigerator, electronics)

Using the estimated worse case power draw of 1800 watts the dc current will be max 165A with a 10% loss in the inverter. This is a worse case, many 15000 BTU units only draw 1300 Watts.

I'm guessing your running the refrigerator as well. The largest 12V DC fridge draws 20 amps DC. If its a residential fridge then you'll need a bigger inverter, and who knows what additional wattage.

So the aux alternator worse case will be supplying 185 amps. but only for short periods of time. A more probable max draw will be in the 130 Amp range.

Depending on the model and make of the alternator, this could be in the acceptable continuous amp range at 1250 motor RPMs. It's difficult to find performance charts for the lower end alternators.

It all depends on the make and model of the alternator, battery charging, and the wiring gauge.

[CSD11]

Gen is 5500Kw. Outside of generator it has on demand hot water heater and 2 furnaces that are propane. Propane tank holds 16 gallons.