Max watts for inverter at idle on 150 amp alternator?

Assuming you are on the road, at present, the quickest way to accomplish microwave use without a generator and without a 120V source, is to use two more 12V batteries and gang all of them together with the largest wire you can acquire. AWG 1 would be a minimum with the batteries situated closely together. The inverter should be located close to the battery gang. Connectivity to the microwave would be either the inverter hard-wired into the trailer or use of a heavy duty extension cord. If an inverter is hard-wired into the load center or to the microwave circuit, a transfer switch is used.

For me, lugging out two extra batteries and an extension cord to use a microwave for lunch is just to much work when I have a propane stove that can accomplish the same process, albeit at a slightly slower speed. Currently, I have an inverter hard-wired into my rig that is used 24/7 but dedicated only to run a small 120V refrigerator and 120V entertainment gear. I have 300AH of batteries and charging is handled by 235W of solar.

If you and the family are heavy microwave users, you may wish to look at the Panasonic inverter microwave ovens. They use less power than conventional microwave ovens.

Microwave generally will need 2000 watt inverter and will pull close to 160 amps from the battery.
Really need four batteries to drive it properly.
Alternator can recharge as you continue down the road.
Final recharge when you arrive and plug in or run the generator.

Fastfwd75 wrote:
I do not have an inverter in the trailer. 12v only or 120v when on shore power.

Is it better/simpler/cheaper to get an alternator for the truck and run a 120v extension to the microwave
or
Install an inverter in the trailer. Seems like this would be simpler for quick lunchtime microwaving. Had no idea my single group 24 battery would be able to do that.

No, a single gp 24 or even two of them will not run a microwave.

Yes and you have heavy one aught wire going to those batteries, just like our 95 Safari 5.9b

The OP is not going to get 55 amps from the front of his truck, through the tt (tow) wiring harness to his batteries

On my MH I have a 145 amp Delco alternator on the 5.9B Cummins motor and I get 55 amps at idle to charge the batteries after evening use of TV and Lights.
HTH

Your truck has an alternator, they only produce 14v,
Your choices are a generator, or inverter
If you use inverter you still have too recharge the RV batteries, either with engine, or shore power
I have no idea how much power your Ford alternator produced at engine idle speed
It won't make much difference anyway, unless you install the inverter in the truck
The charge wires from truck to tt, are too small, so is the fuse in the charge circuit, the inverter in the tt will draw most of its power from the tt battery, it might even blow the trucks charge circuit fuse, going to the tt,

Hi,

Full output may be available but the alternator duty cycle won't allow you to do that for long.

I can safely run my fridge which is 325 watts. If I run the 1200 watt water heater in about 10 minutes the voltage starts to sag from the chassis. I've done this at highway speeds.

I have observed over 70 amps going to the "house" when doing the above. I have doubled up on the charging path and use automatic circuit breakers rather than fuses.

If the inverter is large enough it will draw from the house battery.

Unless you "beef up" the charging path you probably won't see more than about 10 amps coming from the alternator. That may be enough to keep the inverter from failing due to low voltage.

I do not have an inverter in the trailer. 12v only or 120v when on shore power.

Is it better/simpler/cheaper to get an alternator for the truck and run a 120v extension to the microwave
or
Install an inverter in the trailer. Seems like this would be simpler for quick lunchtime microwaving. Had no idea my single group 24 battery would be able to do that.

Your battery will carry the load for microwave use and the long run from the engine to the trailer battery would not carry the load. Meaning the light wire and length would not supply the full output of the alternator even running full tilt. Leaving it idle should be ok but there is a chance you may pop the charge line fuse.

Just run your microwave for lunch, then drive away while the battery refills. Or if you have a mind to you could mount an inverter under the hood (lots of room ha ha), and then the full alternator output would be available.