Hi,

I am putting a 5000 BTU window AC unit in my camper van to be run off a 2200 watt inverter generator. I do understand that is surge wattage and from what I have googled may or may not be enough to handle the compressor start up. In either case I have 2 deep cycle 12v batteries I would somehow like to link with the AC and generator. I want the batteries available for any surge above the generator's top end and ideally have the same batteries charged by the generator when the wattage is there AND a charge is needed.
So basically I'm trying to do what a car system does but uses an alternator instead of generator. Any wiring ideas appreciated.
Thanks

 

Wire it up as a normal 12 volt system. Other than having larger than typical cabling to connect everything on the 12 volt side it should be a simple circuit.

As for the alternator I would recommend getting a larger frame size commercial grade unit rather than a common automotive one. Around here at Napa a good 140+ amp continuous duty rated commercial application alternator is around $150.

https://www.napaonline.com/en/p/WIL90014297

They are also more efficient than most common automotive alternators and can easily run at their full out output off of a 5 HP engine as well.

 

Wire it up as a normal 12 volt system. Other than having larger than typical cabling to connect everything on the 12 volt side it should be a simple circuit.

As for the alternator I would recommend getting a larger frame size commercial grade unit rather than a common automotive one. Around here at Napa a good 140+ amp continuous duty rated commercial application alternator is around $150.

https://www.napaonline.com/en/p/WIL90014297

They are also more efficient than most common automotive alternators and can easily run at their full out output off of a 5 HP engine as well.

I realize I made it ambiguous but I don't want to power the 120v AC 5000 BTU window AC unit off the alternator at all. Forgetting charging the 2 deep cycle batteries which I can figure out myself it boils down to how to hook up the batteries (along with what electric "gizmos" in the circuit) so that if the AC compressor start up surge goes a little beyond the inverter generator's capacity the batteries "kick in" to assist with the surge but otherwise remain outside the circuit so they don't drain by running the AC along with the generator.

 

I am putting a 5000 BTU window AC unit in my camper van to be run off a 2200 watt inverter generator..........
In either case I have 2 deep cycle 12v batteries I would somehow like to link with the AC and generator. I want the batteries available for any surge above the generator's top end and ideally have the same batteries charged by the generator when the wattage is there AND a charge is needed.

Sorry but there's not an easy way to boost the AC from a generator using DC from the batteries.
You would have to use a DC-AC inverter and then sync its AC output phase and voltage with the generator output, which is not a trivial task.

So you either need a larger generator or a smaller air conditioner if that generator won't start the AC unit.

Edit: The 5000BTU AC unit I looked up only takes 3.8A@115V which is only 437W.
Sounds like your generator may be able to start that.
What is the generators momentary peak output?

One thing that would help a little is to delay the start of the AC fan for a few seconds until the AC compressor motor starts.
You would need to add a time-delay relay in series with the Fan wiring.

 

I haven't purchased either the AC or inverter generator yet. I do know these generators are boxed with surge rating shown with 2000 watts being a common size but supplying about 1800 running watts. I understand what your saying and think a larger generator will be the way to go. In fact Craigslist shows two Honda 2800 watt new in the box inverter generators for $500 each and that price is so low ($999 the lowest anywhere else) I'm skeptical.

Thanks though- with no easy plug in I know which direction to take.

 

I haven't purchased either the AC or inverter generator yet.

I would suggest trying to get the highest efficiency, lowest current AC unit you can find.

Craigslist shows two Honda 2800 watt new in the box inverter generators for $500 each and that price is so low ($999 the lowest anywhere else) I'm skeptical.

He may have acquired them from his midnight appliance supplier.