AC while driving with inverter.

[Wygantmb]

Let me start off with I know this will NOT work with the factory setup. For me everything I do is custom. I'm just looking for some insight and someone to double check my thoughts. Starting from the front of the Coach (2012 Greyhawk 31FS) I want to upgrade the factory alternator (120 amp) to a 225 amp. Then run a cable to the house battery most likely with 2/0 cable. I would use 500amp battery isolator so that the inverter would not draw off of the truck battery while the engine isn't running. Next would be to upgrade the wire running from the house battery to under the rear bed to handle a bigger draw. Then replace the 1000 watt inverter with a 3000 watt (5000 momentary peek). From my calculations the 15k ac unit runs at about 1990 watt and starts at about 3500 so the 3000 watts inverter should be plenty. This system would not last long with the truck off. We don't boondock so I'm not worried about that. I'm really just looking for a way to run the house AC and fridge with out needing the generator running or burning up valuable propane. If I stopped for any length of time I'd run the generator. Any and all comment are welcome.

[Grumpy]

Did you switch the geny to propane? JAYCO always used gas genys in their motorhomes.

[RayPayne]

Different RV than yours, but I did similar. With dual 280 Amp alternators it worked, but I also had the hard start capacitor installed too. The AC isn't the only load on the alternator so I'd seriously consider dual to do this if you can. With the chassis AC running as well it will cycle the house AC on and off a fair bit as you drive.

[pconroy]

I just run the generator while driving

[RayPayne]

Originally Posted by pconroy

I just run the generator while driving

I found the generator running while driving was requiring more maintenance, using more fuel than the inverter setup, and added to the concern of stretching fuel stops when I was looking for cheaper fuel. Fuel in Canada can be pricey is certain areas. The generator would cut out at just over a quarter tank. That left me with a good range left in the tank and no AC for the house. The inverter isn't the simple solution for the AC but there is some benefit to it under the right conditions.

[Mustang65]

I believe adding the higher output alternator and the cost of running the RV's aux generator will be a wash. When that alternator is putting out all that power it is going to have a major impact on your RV's gas mileage. Not to mention that the automotive version of the alternator may not stand up to the non-stop usage and get pretty hot, which may affect its operational life. Aux generators also run at a set RPM, unlike the RV motors.

I personally would use the RV's aux generator. I would rather pay for maintenance on the Aux gen than on the RV motor because of the extra load on it.

Just my thoughts,

Don

My Registry

RVing with SOLAR

[RyRoRyan]

I would not recommend using an automotive grade alternator to run your AC units on a continual basis. All of them have their rectifiers built into the unit and will get damn hot trying to continuously supply that much power. But have no fear...people have thought of this already. There are companies who make underhood generator units with their controllers out of the engine bay to run cooler.
http://www.fabcopower.com/generat/bgen.htm
These guys make them, but I dont know their quality.

Aura Systems Inc - AUSI
Aura is better, but more expensive. They have military grade units as well. However this will for sure do what you need it to do.

The only thing that may be a concern here is running when you are at a stop light idling. I dont know if they can supply that much power at idle. The Aura maybe, I seriously doubt the other one could.

[memphis02]

Several have commented about the tax on your vehicle's engine, but I thought I would go ahead and weigh in:

I would recommend looking into Iraggi Alternators. These folks build custom stereo alternators that are designed for the type of abuse you're planning on throwing at this system. -I would actually recommend you look at something around 320-350 amps so as to deal with the peaks your inverter will throw at it, as well as service any other accessories you may be running / ECM etc.

As others have said, you're going to be placing immense load on your vehicle's charging system doing it this way. -I recall a gentleman using 2 of the above alternators on a Ford 5.0 V-8 stalling the engine when current was being drawn. I don't recall the exact formula, however, I believe you need to subtract around 8hp for every 100 amps you're pulling from an alternator. -Keep in mind, this is HP from the CRANK, not your RWHP so losses at the engine may end up being multiplied once it makes it through your driveline.

You might also look into different pulleys as you will want your alternators turning at specific RPMs to achieve ideal power generating / cooling performance.

[Dustdevil]

There are two ways of rating generator windings and designs. First is the output a winding CAN achieve, and the output a winding SHOULD achieve. The limitations are the laws of physics, and the price to be paid when operating outside of those laws is reliability, which often translates to cost and headaches associated with a system which fails often.

I am afraid that If you are looking to do this as a means to reduce cost, you're fooling yourself. What you save in fuel you are spending in replacement of parts, labor, and loss of use. Sure, there are ways to deal with the desire to operate small and purpose-built generators at output capacities well beyond anything they are designed to handle. You can build them to live for a period of time in the extreme heat you're going to encounter. You can build them to output a larger amount of power at a lower speed. And you can sometimes engineer the stators and rotors to deliver a higher current than the typical copper wires and insulation systems were originally designed to output. But you don't get something for nothing. There is a price to pay. That price, as I mentioned, comes in the form of more cost and less reliability.

If you just want a project, and don't care about the cost, you could end up with a very trick looking setup, as long as you're prepared to live with its shortcomings. I would simply run the generator and put up with fewer tantrums.

[RayPayne]

Originally Posted by Dustdevil

If you just want a project, and don't care about the cost, you could end up with a very trick looking setup, as long as you're prepared to live with its shortcomings. I would simply run the generator and put up with fewer tantrums.

While I have done similar to what the OP is after, I have to admit I love the projects to prove they can be done and work. Anything not canned and done right is expensive.