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Discussion Starter #1
I am looking for a little advice here, maybe from someone who has done this before...
Here it is in short form.... I am wanting to hook up a belt-driven generator head to my 82 VW Rabbit, something I can bolt on and take off as needed. I was looking at the pulley set-up on the car, and was thinking bolting another pulley to the alternator might be the best way to go. I am concerned about messing with the balance on the alternator, so I was wondering if anyone has done this sort of thing before.
Thanks! greg
 

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Don't leave out the possibility of a using a PTO shaft type set up, this might be easier to fabricate, what purpose do you have in mind, auxiliary power?
 

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Discussion Starter #3
moopups said:
Don't leave out the possibility of a using a PTO shaft type set up, this might be easier to fabricate, what purpose do you have in mind, auxiliary power?
I definitely considered the PTO option, but at present I dont have a tractor. I envision using this generator as auxillary power, recharging batteries on my PV battery setup in winter, and occasionally running a high-powered air conditioner for short spells to cool down the house.
I have pretty good access to WVO for making biodiesel to power the diesel Rabbit, so the fuel is relatively cheap and relatively low-impact, enviormentally speaking. Both of those factors are figuring in to my pursuing this method of power generation.
A more appealing option would be a stand-alone diesel generator, but after having priced them, and considering the fact that I already have a diesel engine in the Rabbit, the belt-driven generator SEEMS like a workable idea. IF I can figure out how to fabricate a suitable mount for it, and connect it to the engine without comprimising the fine German engineering of the VW...

My present idea involves drilling a few holes somewhere suitable in the engine compartment, and mounting a plate that would stay permanently attached to the car, then fabricating some sort of mount on the generator that would allow it to be tensioned down, much like an alternator. Hopefully something that could be set-up and dismantled without too much trouble.

OR.... what about taking off one of the drive wheels, and fabricating something there?? hmmm, that might be even simpler and less trouble...
:)
 

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Do a search on converting the GM alternator from 12 volts to 110AC. It is feasible.
 

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hmmm, you want to be able to drive the car? or is it to be a stationary engine?

the wheel thing could be done....built like a drive on dynometer. but you are going to loose about 25% efficiency by friction losses in the drive system.

i always wondered if the vw or other diesel could be used by using the cruise control to maintain rpms on the generator. i have a chance to purchase a small issuzu(yeah i know spelling) diesel engine for $100 ....kick myself for not getting it.

wonder if vw has a high amperage generator on their books...if so maybe it could be bolted in place of the stock unit.

interesting project, keep us posted?
 

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If you plan on making AC, for use in appliances your nearly out of luck, as the car has no governor to keep the engine running at a steady rate, the wheel traction idea would work if your car has cruse control, as it would work as governor, (Aces post),

If all your wanting is DC for battery charging it will work as the speed is not need to be kept constant,
on AC the speed is what controls the frequency, and motors and even some electronics need the constant 60 cycles to make them work on speed and not over heat,

Tractors motors use governors to keep them running at a steady rate, cars don't
 

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I was not thinking of a tractor PTO, but rather a prepared place where you could place the VW into, lift the hood, attach a PTO shaft to a mounted generator, and operate from there. At what RPM does the generator most effectively operate? How do you maintain that engine speed?
 

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Discussion Starter #9
I've not made the generator head purchase yet, the closest example I have seen of 'belt driven generator' is in the NorthernTools catalog, retailing for about $650.
Yes, I have been thinking how to maintain a constant speed on the thing with varying loads being applied, the 82 VW rabbit has no cruise control... I was thinking of some sort of mechanical governeror, but my research into this has only begun... And then there is the issue of pulley sizes, gear ratios, and all of that. Definitely got some math to do here.
And yes, the car would still be driveable. I would like to be able to pull the car up close to the house, bolt on the genny, and get some battery charging done.
Since I already have an inverter, maybe I shold look into a straight DC generator, and just feed the power right into the battery bank? That would eliminate the need for a governing system. My first thoughts were to just fix the throttle position about halfway open, and let it ride there...
Hmm.... how do those PTO driven generators govern the speed, since they are a seperate unit and operate at the RPM of the pto shaft? Back to the governor system?
 

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Rockin In The Free World
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Neat project. Some thoughts :

- ideally, and if the engine has enough power for the load, you'd like the diesel engine to run at idle
- if the engine idled at 900 rpm and your gen head needed to turn at 1800 rpm, you'd need a 1:2 gearbox
- you may not need a governer - as many modern engines are computer controlled - and have idle compensation circuits built in - i.e. if you turn on the headlights, the heater and the wipers, the computer will maintain idle rpm regardless of the load (I've no idea if a 82 VW has a computer)
- personally, I'd opt for building the gearbox/genhead on a mountable plate/frame, with matching mounts under the hood
- simply open the hood, mount the generator rig and attach the belt

- also, you may be able to "fool" the engines computer (again, if yours has a computer): for example, you want an engine to idle at 1800 rpm instead of the normal 900 rpm (say for example you did not want to run a geabox and just wanted the engine to turn 1800 rpm constantly)
- fool the computer by intercepting the signal which inputs the rpm to the computer and modify that signal accordingly
- give this project to any electronics geek and for $20 they could build you the circuit in a neat little box with on/off switch, dip switches to modify idle, maybe a tach, etc. etc.
 

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i have a whole earth type book around here somewhere where the guy puts extra batteries in his car trunk and charges them during his regular drive. then used the charged batteries to power his house at night. by power i mean run a few modest items..an isolator and breakers or fuses for safety will be needed. advanced auto, auto zone, jc whitney or your rv dealer will have the parts needed.

there is a safety problem with remote batteries and runs of cable in an auto accident. and it will not be cheaper than grid power,,,but i'm sure it will work. your car alternater will usually charge the standard battery in a few minutes from the drain of a chank up.

have you seen the lawn mower engine powered 12 volt generator offered by epicenter or something like that? do a search for the description above and it should show up


anyway, there used to be cruise control kits that used a magnet on the driveshaft to pick up rpm to set the aftermarket unit....not sure i've seen them lately. but the magnet couldbe attatched to just about any rotating shaft to trigger the cruise control (even most of the oem units pick up a signal from a hall effect plate in the output shaft of the transmissions). i could see an aux. pto made to fit maybe the crankshaft pulley nut on the front of the engine...but that would also entail making a passage through the body/radiator....maybe not such a good idea after all.
 
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