Belt Driven Generator

[FamilyBusTX]

Has anyone played with or made work, a 12, 24, or 48-volt generator that's belt-driven off of the engine? I want to run my rooftop AC while I'm underway but don't want to have to run a separate fuel-powered generator. I have done some basic google searches but this doesn't seem to be an area I have found a lot of details on. I would assume the generator would be supplying power through a charge controller to a large battery bank which feeds a DC to AC inverter to provide the 120AC for the Air Conditioner.

I apologize if there is a forum post already addressing this issue. Please link it and I will go there and remove this one. Thank you so much for your input

[CHEESE_WAGON]

I wouldn't spend $100 to save $10. Not worth the effort.

[sproutroot]

if you're looking for a way to charge your house batteries while the engine is running, you merely need to hook up the house batteries to the starter batteries with a battery isolator and a fuse in between.

your alternator is capable of charging two sets of batteries assuming your wiring is adequate. you should be able to figure out the output of your alternator. you can swap in a bigger one if it's not up to the task of running the A/C.

most generators output AC current (although you can also get DC generators), whereas alternators and stators output DC.

[FamilyBusTX]

Cheese_Wagon. I'm not sure what you're trying to say? I would only be running the engine when I'm underway. It wouldn't be running once I've reached my destination so I wouldn't have any other reason for a fuel-powered generator. We don't dry camp so any place we park for the night would have shore power.

[FamilyBusTX]

Sprout I'm not trying to just charge batteries. I'm trying to provide the amperage/wattage to run the 120V AC air conditioner off of the engine.

[sproutroot]

Originally Posted by FamilyBusTX

I would assume the generator would be supplying power through a charge controller to a large battery bank which feeds a DC to AC inverter to provide the 120AC for the Air Conditioner.

This is the system I described above. It's simpler than you think.

[CHEESE_WAGON]

Originally Posted by FamilyBusTX

Cheese_Wagon. I'm not sure what you're trying to say? I would only be running the engine when I'm underway. It wouldn't be running once I've reached my destination so I wouldn't have any other reason for a fuel-powered generator. We don't dry camp so any place we park for the night would have shore power.

My browser is a POS and likes to jump down the page before I can read the whole post. Misunderstood what you were saying. Revised. Apart from the isolator idea from sprout (my first choice), you might consider using a couple alternators driven by squirrel cage blower wheels mounted on the roof... Air scooped in, turns the blower wheels, which turn the alternators. Do you have a separate house battery bank?

[Truthseeker4449]

Could try looking into one off a fire truck, which are designed for such heavy duty usage. They aren't going to come cheap and they will be huge.

[FamilyBusTX]

I am currently in a fresh build. I can have whatever I need at this point. Just trying to brainstorm practical installs for the future

[sproutroot]

mine isn't wired exactly like this, but it should give you the right impression. follow the A/C circuit all the way back to the engine bay. those are the components you'll need.

[dzl_]

Originally Posted by FamilyBusTX

Has anyone played with or made work, a 12, 24, or 48-volt generator that's belt-driven off of the engine?

Essentially, I think you just described your vehicle's alternator

I would assume the generator would be supplying power through a charge controller to a large battery bank which feeds a DC to AC inverter to provide the 120AC for the Air Conditioner.

So basically I think this is the system you already have (or could have with a few modifications), right?

1. A generator: your alternator (or a second alternator if you need more power)
2. A 'charge controller': this might be something like this if you use lithium batteries, if you have a lead acid, I think something much more basic like this would be all you would need
3. A Battery Bank: your "house" battery bank (how you connect it to the alternator would depend on the specifics of your setup)
4. An Inverter: Another standard component of your 'house' electrical system

[Native]

We have done this.


We have a 350A secondary alternator driven by the engine. It is hooked up to the house batteries. The house system is hooked up to our converter/inverter which powers our alternating current house loads, which includes our roof-top air conditioner.


So yes, it can (and has) been done. It is NOT cheap. You have to add a bracket to the engine (and change the belting system), mount the alternator, run battery cables to the house batteries, install the converter/inverter, install the house circuits, and install the air conditioner.

[TheArgobus]

I almost bought one of these bonus alternators to charge while driving: https://www.electriccarpartscompany....rom-Alternator


But then I realized the one I already had was like 150 or 180 or something like that amps. So then I was going to buy that DC to DC charger on that page, but then I decided my house bank was going to be 24V instead of 12.


BroccoliBus (also on this forum) installed an inverter on their alternator, and then plugged that inverter into a regular 120V to 48V lithium charger. It may not be the most efficient but it works. See his recent tour here he talks about it:

https://www.youtube.com/watch?v=AoxV...ture=emb_title

[sproutroot]

Originally Posted by sproutroot

mine isn't wired exactly like this, but it should give you the right impression. follow the A/C circuit all the way back to the engine bay. those are the components you'll need.

somehow the image I attached here was forbidden by google, so I sketched this up.

[PNW_Steve]

Your wiring is all upside down. All of the electrons are going to run out.

[sproutroot]

fixed it.

I also break my cookies in half to dump the calories out before I eat 'em.

[cadillackid]

the other piece of this is expecting to actually stay cool with a single rooftop A/C on the road?

[FamilyBusTX]

Yup. Will work just fine. Just had a generator question.

[Native]

Originally Posted by cadillackid

the other piece of this is expecting to actually stay cool with a single rooftop A/C on the road?

You make a valid point. There are a lot of variables involved. In our uninsulated 38' bus with three coats of elastometic paint at 90 degrees F ambient, our 13.5K BTU Coleman Roughneck keeps the inside bearable. At about 85 degrees it starts to get a touch too cool for me and at 80 degrees it is way to cold. On the other hand, at 95 degrees it is *almost* like being in 90 degrees with only the windows open. At 100 degrees, it is hot inside ... like 90 degrees.


More insulationandshutting off the back would help a lot.


Of course, we'll not be keeping out soda cool by the output vent either.

[PNW_Steve]

It does really depend on where and when you use the bus.

I spent some summers in a 40' bus with 2" of spray foam insulation and two 12k roof airs.

I was very comfortable in Seattle in July. Bullhead City, AZ and Lubbock TX were a different story.

In Bullhead, running both airs, I had weeks at a time that I struggled to keep it in the 80's inside in the afternoon.

I have amended my bus rules: Summers must be spent North of 43 degrees North. Or above 4000' in elevation.