Towing With Aux Generator & AC On

[Brad Burgess]

Hello All

Still in the process of downsizing from Class A pusher to TT. We usually stop at lunch time in our class A and eat in the coach, which is cool as the AC (or heat) has been on during travel. Is it possible to run an aux generator (Honda 3000is) in the truck bed and have it connected to the trailer while underway so that the TT AC can be operating while underway? In the west during the summer the interior of the TT would seem to get quite warm while towing if no AC is on.

Thanks,

Brad Burgess
Looking

[xrvr]

As long as you can keep the power cord connected, it should work. Actually sounds like a great idea. Jim

[daveswenson]

Make sure that the generator is large enough for the AC, A 3000 should power a 13500 btu AC but probably not a 15,000.

[DKB_SATX]

Originally Posted by daveswenson

Make sure that the generator is large enough for the AC, A 3000 should power a 13500 btu AC but probably not a 15,000.

Dometic Penguin II "high capacity" (what they used to call 15000 btu) at the rated load for both fan and compressor is 16A, at 120v that's 1920 watts.

My Yamaha 3k generator is rated at 23.3 amps/2800 watts continuous output.

Yes there may be other short-term loads like the converter (which should still be well within the continuous capacity of the 3k generator) but if your AC is actually using its rated amperage most or all of the time, it's defective. The usual running amperage should be lower than the rated.

[CDONA]

There will be 12v charging the batteries from the 7 way TV plug, along with the 120 ac powering the converter, charging the batteries.
I don't know if there will be a conflict?
I've wondered about leaving the 7 way plugged in while I'm on shore power. But I think alternator diodes will prevent back flow to the TV batteries on 12v

[Skater]

Originally Posted by CDONA

There will be 12v charging the batteries from the 7 way TV plug, along with the 120 ac powering the converter, charging the batteries.
I don't know if there will be a conflict?

No conflict. Motorhomes do this all the time.

I've wondered about leaving the 7 way plugged in while I'm on shore power. But I think alternator diodes will prevent back flow to the TV batteries on 12v

Depends on your tow vehicle. Mine disconnects the 12 volt constant power when the ignition is off, so it's completely safe to leave it plugged in. If the tow vehicle doesn't, though, the camper could draw down your engine battery or cause other issues.

[daveswenson]

Originally Posted by DKB_SATX

Dometic Penguin II "high capacity" (what they used to call 15000 btu) at the rated load for both fan and compressor is 16A, at 120v that's 1920 watts.

My Yamaha 3k generator is rated at 23.3 amps/2800 watts continuous output.

Yes there may be other short-term loads like the converter (which should still be well within the continuous capacity of the 3k generator) but if your AC is actually using its rated amperage most or all of the time, it's defective. The usual running amperage should be lower than the rated.

Rated load is one thing, but startup torque can easily double that (for a very short period) but if you don't have enough peak load capacity you can damage your compressor motor. Just sayin' "Make sure you have enough."

[JFScheck]

My Yamaha EF3000iSEB is a 3000 watt generator with 500 watts on reserve (utilizes its onboard battery) for up to 10 seconds thus providing the A/C unit when connected with enough capacity for when its kicks on its compressor.

[DKB_SATX]

Originally Posted by daveswenson

Rated load is one thing, but startup torque can easily double that (for a very short period) but if you don't have enough peak load capacity you can damage your compressor motor. Just sayin' "Make sure you have enough."

The generator puts out just over 29A briefly in "boost" and 25A for longer peak duration. Find cases where properly-working 15k BTU ACs and quality 3k generators (let's say Honda and Yamaha inverter-based units for the sake of discussion) are incompatible and I might worry more.

Dometic, for their part, says you need a 3.5kw generator minimum for both the 13,500 and "high capacity" AC units. CYA requirements, I suppose. I only personally know 1 person with a larger-than-3k generator, yet several with 3k generators and 15k BTU ac units who have no complaints.

The paired Honda 2ks only add up to about 26A rated capacity and a bit over 30A peak (and are noisier paired than a 3k Yamaha or the bigger 3K Honda, though I think the 3k Handi may be nearly as noisy as the paired 2ks.)

[TavnAsh]

The AC in our 30 bunkhouse is never off, except for the 5 min between unhooking from the house to the truck generator. I have two honda 2000s, uncovered (exposed to weather) in the truck bed (around 5000 hours on them now) connected to a 12 gallon marine gas tank. I installed a 30 amp line that is wired near the 7 way at the hitch, connected into the electrical system with a marine style 30 amp rotary switch to select shore power or generator power. After I connect the rig and warm the generators, everything gets switched over and the camper is always cool for our stops. I have been doing this now since 2005 with the same Hondas. Getting ready to install a permanent diesel generator in the bed next .