NEED MY A/C

I'm not sure how you are rigged up but the easiest and best solution would be a 3000 watt generator on a hitch cargo carrier.

For running a 13,500 BTU A/C and if you really don't want to install an Onan 2800 generator or carry a portable generator then look into under the hood mounted generators. One of these might be what is used in the E-trek

Mobile Electric Power Solution, Inc. (MEPS) - http://www.meps.com/products.html

Aura Systems Inc - http://www.aurasystems.com/pages/prod_intro.html

Raven Technology - http://raventechpower.com/

Fabco Power - http://www.fabcopower.com/generat/bgen.htm

It might be best to have an Onan 2800 generator installed under your Roadtrek though.

I think whomever told you your AC unit pulls 30 amps is totally wrong.. It probably pulls in the area of 15 to 20 amps. Just a guess but I am sure its in the ball park.

For an inverter you need to do the math but the formula is P/VxI . "I" being current, V being voltage and P being power.
I am thinking in the area of 1800 watts power or a little more just to power the AC unit. Now you need a inverter to produce a minimum of that amount of power. Thats a lot of power coming from your alternator and battery. Probably max it will produce.

A small onboard generator would probably be best.

BTW if the unit truely has a 30A draw you need to double the math above. I only figured on 15 amps.

Hi,

A 13500 btu air conditioner may draw about 1300 watts. Start up surge would be double that, so a 2500 watt pure sine wave inverter may work. 3000 watts would be better. Go Power and Samlex make units that size.

Beef up the charging path from the engine alternator to the house battery bank with thicker wire. The isolation solenoid may also fail.

Expect to shorten the life of the alternator and when it fails replace it with a larger capacity unit.

Look into after market add on "engine" air conditioners. It may be less expensive than doing the above.

Not a practical solution for you. A 30 amp draw would require at least a 3000 watt inverter. And it would take a very big battery bank to sustain it for more than a very short time. It takes a lot of 12v amps to convert to 110v amps. A much better solution for you would be the Honda generator. But I also question the 30 amp draw. A 30 amp load is typical for an entire RV with a single roof air. The roof air should only be about a 20amp draw by itself. The other 10amps are for lighting, Micro, etc. I'm guessing a Honda 2000 or 3000 would do it for you.