Converting a 90mm generator to 12v

Hey there, just wondering if anybody knows where or if I can get my 90mm 6v generator converted to 12v in Aus, and what I might expect to pay to get it done?


Cheers!

I am guessing that a 90mm is the standard 6v generator?

A friend of mine did this may years ago. He had to strip the windings from the armature and rewind it with two cables that had to equal half of the cross sectional area and twice the number of windings. Many hours of labour. It can be done but would be very expensive.

Some of the industrial engines had the small diameter 12v generator like the porsche.

Try an industrial motor rewinders or maybe an auto sparky would do it.

The field windings are quite simple and just wound into a round cornered rectangle that the iron core then clamps to the genny body.
The rotor winding is a little more complicated due to how the rotor is wound with multiple windings that are then soldered to the commutator contact points 180 degrees out from each end of the winding. It's do-able but requires much patience. 🙂

I have this if you are interested, no armature as it was so rusted I had to push it out in a press. As far as I know the coils/pole are longer in the 12 volt version.

Free as it's of no use to me. Just pay postage. Should have the end plates somewhere.

it used to be done quite easy but now days no auto elec would want to do it

better of finding and early Porsche genny

Thanks for the replies!

I read that the 6v generators put out more than 12v, so you can succcessfully run a 6v generator used in conjunction with a 12v regulator, although it won't charge the battery at idle very well, if at all, and may only last a few years before it burns out with too much use....has anyone else heard about this? Maybe ok for a car that isn't driven a whole lot......

My second 36hp has a milled generator stand to fit a 105mm Porsche generator on it, which works great, but I want something a bit more original looking for my old speed project motor and don't want to hack up a good original 57 block, so will have to fork out for something expensive I guess haha!....

I guess I will look for a Porsche generator then, since thats the easiest method, shame about the lack of holes for a regulator for an original VW look though, but I guess I can drill and tap some holes for one.... It's a shame that there aren't easier/cheaper solutions for a 36hp 🙁

This might help:-

http://www.allzim.com/store/zims-premium-remanufactured-generator-356-converted-to-12v.html?category_id=452

356 are 25 amp vs industrial generator at 38 amp, depends on your needs.

matara wrote:This might help:-

http://www.allzim.com/store/zims-premium-remanufactured-generator-356-converted-to-12v.html?category_id=452

Thanks for the link! I can't believe how pricey though! thats nearly $900 for a generator if I incur the core charge, otherwise, I still have to send a core over to the states, which will still be nearer $700 🤪

mackaymanx wrote:356 are 25 amp vs industrial generator at 38 amp, depends on your needs.

Yeah, that occoured to me before! the 25amp would be enough for lights? I don't use a whole lot else really, but may eventually build a small self contained stereo off an iPhone with a second battery in parallel with the cars battery....I'm guessing that's where the issues come in with the lower amperage right? 😂

If I had the time I'd say I'd give it a go for you as being an electrical engineer I've re-wound a few things in my time. Heck I've even got a spare 6V genny in my stash somewhere.

Anyhoo, the idea of running a 6v with a 12v reg is a bad idea as it's running outside isn't constant delivery zone and will get pretty warm and hence fail at some point that can be determined.

This place can do it

Rapid Rewinding Pty Ltd
50 Dollis St, Rocklea QLD 4106

psimitar wrote:If I had the time I'd say I'd give it a go for you as being an electrical engineer I've re-wound a few things in my time. Heck I've even got a spare 6V genny in my stash somewhere.

Anyhoo, the idea of running a 6v with a 12v reg is a bad idea as it's running outside isn't constant delivery zone and will get pretty warm and hence fail at some point that can be determined.

Ahh, I wish you would haha! Theoretically, how much would you charge? 😂

Old Dubber wrote:This place can do it

Rapid Rewinding Pty Ltd
50 Dollis St, Rocklea QLD 4106

cool, have you used these guys before? they look expensive😂

Probably $35 an hour but I'm not sure how long the rotor would take. The field windings would be about an hours work but the rotor could be 3 hrs plus. Having not re-wound a genny I can't be more specific than that.

I doubt if you could rewind an armature in one day.

I used to do them as an apprentice many years ago.

The friend of mine that did took a few days as it was tight to get double the windings in the same space. He ended up using two conductors. I can't remember whether he had to modify the feld coils or not.

AA003 wrote:I doubt if you could rewind an armature in one day.

I used to do them as an apprentice many years ago.

The friend of mine that did took a few days as it was tight to get double the windings in the same space. He ended up using two conductors. I can't remember whether he had to modify the feld coils or not.

As I've never done a genny before the rotor rewind time was a total guesstimate. I do know they aren't easy though.

I would hazzard that the field would need rewinding too just due to basic ohms law or you will greatly increase current and hence heat in the field winding.

psimitar wrote:As I've never done a genny before the rotor rewind time was a total guesstimate. I do know they aren't easy though.

Very hard trying to get twice the number of windings into the same space.

I would hazzard that the field would need rewinding too just due to basic ohms law or you will greatly increase current and hence heat in the field winding.

I'm just wondering if the regulator would take care of it?

AA003 wrote:Very hard trying to get twice the number of windings into the same space.

True but normally with windings you either double the length or reduce the wire gauge to increase the resistance but the latter method means that current capacity could be less.

AA003 wrote:I'm just wondering if the regulator would take care of it?

Possibly but using dissimilar wire gauge will make the regulator work harder as the field and rotor windings magnetic field interaction would possibly be quite different than in similar winding gauge.

Has got me thinking that I'd really like to check out how Porsche did there small body 12v genny, altho does kind of explain why the Porsche version has a lower current output. 🙂

psimitar wrote:

AA003 wrote:Very hard trying to get twice the number of windings into the same space.

True but normally with windings you either double the length or reduce the wire gauge to increase the resistance but the latter method means that current capacity could be less.

Yes the wire gauge will be half of the cross sectional area which will halve the current output. The wattage will be the same.

Did this, well paid for a 12 volt rewind for a type 3 generator, $700

6621104 wrote:Did this, well paid for a 12 volt rewind for a type 3 generator, $700

OUCH 🤪 🤪 🤪