Alternators for Mag engines

[bobthompson]

Does anybody have any knowledge of alternator conversions for Mag engines? Is there anything that can pick up from the existing drive?

[Charles P]

Does anybody have any knowledge of alternator conversions for Mag engines? Is there anything that can pick up from the existing drive?

I asked the question of the UK supplier.
His answer was that he believed their alternator fitted all models of Austin 7. I gently pointed out the differences, supplied a couple of pictures and asked if he had any plans. The answer was no.


c

[Stuart Giles]

Don't know of anything that would just bolt on, But I have one of these in the workshop to fit onto an A7 project where there's not enough room for a dynamo or a dynamator. Wouldn't be too difficult to adapt to a Mag engine.
https://www.ebay.co.uk/itm/Alternator-Fo...SwM1hbUuz7
It's a really small permanent magnet alternator; pushes out 14A @ 12V maximum. Needs an external regulator, there is a version of these that will drive an ignition warning lamp -but not so useful if you have the SM3 switch panel. I bought my alternator and regulator from a US supplier, even after paying the shipping etc. it was still cheaper than the ebay item I linked to.

[Robert Foreman]

Very interesting Stuart. 
  Could you please furnish me with some dimensions? 
Regards, Robert.

[Stuart Giles]

Certainly Robert, might take me a day or two to locate the box it lives in. Obviously looks nothing like a mag dynamo, but would be nothing like as obtrusive under the bonnet as the Citroen 2CV or Nippon Denso altys I've seen used.

BTW, I found out about this alternator and regulator setup from some old bike people, has better reliability more poke than most 60s/70s bike altys, the regulator is also a lot more sophisticated than the "boil your battery dry" Zener diode setup fitted to lot of machines back then.

[Colin Reed]

HI All.
Dimensions

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HI ALL,
Just an update the alternator does not require input voltage to work only the regulator as you will see from the size of the heat sink they need to be fitted in a open space to allow for cooling

Colin 
NZ

[Stuart Giles]

Colin,
Well done for that; your drawing has saved me some rummage time!

And yes, being a permanent magnet alternator it doesn't need voltage to excite the alternator's field; but also, this means that there is no control over the permanent magnets' field strength, so the regulator needs to sink some energy when full charge isn't required by the battery.

The only factory installation I've seen of one of these had the regulator mounted to the garden tractor's metal frame, allowing it to act as a heat sink. Otherwise, it didn't appear to be in an especially well ventilated area.

[Robert Foreman]

Thank you Colin and Stuart. 
What kind of revs does it need to produce a good charge?

[Charles P]

Some interesting tales from the motorcycle people here (and exploded pictures)
https://impbarn.blogspot.com/2011/12/sun...agnet.html
and
http://www.britbike.com/forums/ubbthread...ype/thread

Edited to add 
https://www.autoelectricsupplies.co.uk/p...tegory/250
Shows output vs rpm

Charles

[Colin Reed]

HI Stuart,
I was just lucky mine was still on my bench from last week other wise it would have been put in a safe place never to be seen again
(Old Age )
Colin 
NZ