6V to 12 V generator conversion (36hp Bug, 356 Porsche)

[danyarger]

Obviously people are doing it and converting the 6Volt 36hp Bug/356 Porsche Generators. Why isn't anybody giving away the secrets on where they get the parts and how to do the conversion. Come on, this is the internet, we are supposed to find all of this stuff for free. I don't want to pay somebody $200-$300 for a generator for a motor I got for $175. I know the rebuilders are rebuilding them for like $30 or less. Why cant we? If I find out myself, I will make a video and make this info available.

[badsix]

i'm converting my 356 to 12 volt with a small dia. porsche 12v gen. i believe they come on the early 912s. these are getting very hard to find so the price go's up. i hope you find some good info here there must be parts avalible to do this.

[danyarger]

What I have found so far aside from everybody saying ("Oh I used to know someone 15 years ago who converted these but they are out of business now") is this. From reading on other websites where people have the same problem with Vintage 6 volt tractors is that they replace something called the "fields" and put on a 12 Voltage Regulator. Well finding a 12 volt voltage regulator is easy. I don't know anything about fields. Other people have said on different sites that all you have to do is replace the voltage regulator to a 12V and the 6V generator will automatically compensate. Those people also said they have done it several times with no problems and that they have actually generated in testing 17 volts briefly with a 6V generator. If what they say is true then paying $100-$300 for a Porsche 356 generator is a huge rip off if all you got to do is replace the regulator. Unless we know for sure and actually taking ours apart, I might be able to assume that the reason the 12 volt VW generators are bigger diameter is because the Voltage regulator is internal not external like the 36 hp versions requiring more space. I may actually try to take mine apart tonight and find out and will post a reply. I'm guessing it's just the guts you'd find in an electric motor (ie shaft, windings, 2 bearings and a case.) If I do get it apart, I'll take some pics for show.

[EverettB]

Call your local electrical repair shop and ask them about rewinding it to 12v.

I don't know of anyone that will rebuild a generator for $30. If you mean their cost, yes, that is possible.

Yes, 6v generators put out more than 6-volts, that's why they need to be regulated. They are not designed to put out more for an extended period of time.

[danyarger]

Ok I have cracked open the shell of my 1957 36 hp generator. My assumptions were correct. There's nothing special inside. Just 2 brushes, a dirty armature on the shaft and 2 coils rapped on the inside. The brushes ground out on the outer case plate. Also that last poster was correct. The 6 Volt generator will put out more than 6 Volts just like the other websites said. All we need is a 12 volt regulator. I'm not saying this will last a long time but it may be enough time to work until I can raise the $300 for an alternator conversion. Apparently they do make a 6 volt generator to 12 volt Alternator conversion kit. What they don't list though is the diameter of the alternator and whether it will fit the generator stand of a 36 hp. I know it fits a 1200 40 hp. But I don't know about the 36 hp. The 40 horse has the removable generator stand which leads to believe that the case is the larger diameter. Most modern alternators have internal voltage regulators. If the alternator conversion actually fits a 36 hp then that would be more beneficial than the Porsche 12 V generators because with the conversion alternators, you can get an output of up to 75 amps which is great for accessories or for the Hydrogen generator crowd.

[EverettB]

The 6v 40hp generator stand is the same diameter AFAIK.

I did some Google searching and it sounds like you will burn up the 6v generator fields by using a 12v regulator only. This is why you read that people replace the field components. The burn-up time depends on your usage. The recommendation I found was to not run any accessories - lights, radio, etc. if you want it to last any period of time.

Think about running a 6v light bulb on 12v and how long that might last...

Don't forget that generators and regulators typically match up in amperage so make sure you use a regulator that has the same or close to the same amperage as your 6v generator.

If you are going to do an alternator conversion anyway, why not just wait?

Hopefully some other will chime in with the electrical specifics and why this is a bad idea...
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[danyarger]

I was going to do an alternator conversion only after I burn up the 6 volt generator first. Some people who have done it on vintage tractors claim to have done it with success. They said without the regulator the 6 volt unit ran at 17 volts for a short time. A alternator kit is over $300 for one made in China but it puts out 75 amps. So your saying the Alternator conversion kit is the same diameter as the one on a 36 hp? I know they list the 40 hp which is a 1200. A 36 hp is smaller than a 1200 though. Its 1100 something.

[Shadd]

The "field coils" are basically wire wound around magnets called pole shoes. They are attached to the outside case of the generator. The spinning armature passes through the field coils to generate electricity. If you doubled the number of windings in the generator you would double its voltage(using thinner windings) This comes at a cost though, you can only get a fixed amount of amperage from a generator. Amperage is a product of the size of the generator(diameter) and the speed at which the coils pass through it.
The relationship between Voltage and amperage can be shown mathematically:
Amperage=Wattage/Voltage
A 6v (36hp)bug generator is 160 watts at 2500rpm
160W/6volts =26.6amps
160W/12volts=13.3amps
The 6V bug generator is severely limited in output already but to trade half of that isn't going to leave you with much.
Using a 12V regulator on a 6V generator isn't much better. See a generator isn't charging all of the time. Its only working when the regulator tells it to. The generator has a duty cycle based on its cooling efficiency. If it is working at full output all of the time it will overheat the fields and eventually burn up. Any added load will only hasten this. Since the whole reason to switch to 12V is to add brighter lights and more accessories this seems like a waste of time.
The question I have is why do you need 12V?
Here are the three main points that I have heard:
1) a 12V lighting system is brighter for increased saftey
2) 12V system is more reliable.
3) 12V components are easier to buy at your local parts store.
These are good points but consider this:
1) Bulb brightness is determined by Wattage NOT voltage. A 6v bulb that is 55W is the same lumens as a 12v bulb at 55W
2) Although 6V has less ability to overcome resistance in an electrical system VW built their system to be 6V. A stock beetle has very little resistance due to Wire quality, short lengths and minimum number of connections. As long as you keep the system stock and CLEAN it will be perfectly reliable. In fact 6V bulbs use a larger filament meaning they are more rugged and last longer than 12V.
3) With the advent of the internet you can have almost anything at your doorstep in just a few days, including halogen 6v bulbs comparable to modern 12v (http://www.snydersantiqueauto.com/search.php?q=A-13007-E&x=0&y=0)
Check out this post for further details
http://www.thesamba.com/vw/forum/viewtopic.php?t=378530&highlight=

[Shadd]

The alternators are the same diameter as later 12V generators, not the same as the 6V generators.

[danyarger]

The reason I need a a 12 V generator is because the whole rest of the car is 12 V. I'm putting a 57 engine in a 69 car. The trans is a 72 with a 12 V starter. I keep getting the same recycled copy and paste answer. "Why do you think you need 12V?" Because the rest of the car is 12 V!

1957 36 HP into 1969 Beetle IRS chassis with 72 Transmission/starter means I need a 12 V coil and eventually a 12 V generator or alternator.

[EverettB]

[EverettB]

[Shadd]

[danyarger]

I'm using the 6V flywheel in the 72 trans. The trans is not original to the car. This kitcar didn't come with a motor and trans, so I had to kind of piece it together with whatever money and parts I could find. I know I'm gonna have to swap out the later throw out bearing and arm for the earlier one. I am curious if I can at least I'll be able to start the motor using a 12 volt battery and the original 6 Volt coil, just to fire for the first time for like 5 mins. I kind of doubt it but it's worth a try.

[my65vert]

thanks for the entertainment.



Step back, think about all that you are trying to accomplish by half assing it together "just for a bit".

Then realize it is much easier and worth while to do it right the first time.


By the way, you can get a 12v generator the size of a six volt one from any brasilian split bus. Contact one of the brasilian members on the site and get one from them.
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Kombisutra;
I'm starting to get little wafts of bus stink coming from the north. Something about the unique scent of drivers seat padding when it's glued together with mouse piss and shit that really gets me going... and I'm smelling it! Oh yeah! Time to start loading up the equipment.

[EverettB]

[paulw49]

Can I ask where it’s possible to get the black Regulator that sits on top of the 90 mm Dynamo. Can’t seem to find one anywhere. I have 1962 beetle 40hp all original 6v components. So I’m trying to keep it stock but want to run 12vs . I found a place to change out the internet’s on the 90mm dynamo so I just need to sort out the regulator.
The only other thing that’s worrying me is I have the big cap bosh
Distributor Bosch . The condenser sits in side. This is also 6v . Where could I buy a 12v one as I don’t think it’s possible to run 6v through it with out burning it out .
Thanks any info be great

[EverettB]

The distributor will work fine without issue

The regulator, are you looking for a black 12v one?
You'll probably have to buy a silvery one and paint it.
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[Jon Schmid]