12volt electrics

Mikeant

Forum User
VOC Member
I was just leafing through some of the articles posted and wondered why people were attempting to rewire dynamos. 40 years ago I solved the problem of the lack of a generator on my Velocette by installing a Fiat 500 car generator. I then approached Dave Lindsley who put me in touch with John Gardner who made me a regulator/cutout to suit. This was very successful. I had an additional clip-on with a 55watt spot hanging wired into a relay switched dip beam circuit. The main headlamp had an E type Jaguar sealed beam unit. I could see at night!
When I tackled the Vincent engine I already had the standard Miller generator. Mr Gardener supplied his standard offering this time, in this one he limits the field coil voltage to 6 volts. Now I have no experience to report since shortly after completing the Norvin rebuild the winter was upon us and then I was sent to Saudi Arabia for work. (Insert usual long story of family, working abroad, paying for the kids)
The point being is that the Achilles heel of the old 6 volt systems was the vibrating contact points of the regulator. Mount such on a piece of vibrating machinery and it does not perform too well. In the diesel engined air compressors on site in those days the regulator box was rubber mounted to help it survive.
Whereas in fact electronically it is relatively trivial to design a circuit to regulate the voltage to 14.2v. The trick is making it bike and weather proof. This is where the JG unit scores being firstly designed by an electronics engineer and secondly it is potted inside a die cast box so it is vibration and water proofed.
I do not know whether JG units are still around. They were a straight forward substitution for the old box. Change the battery and the bulbs for 12 volt items and let there be light! No mods were required to the dynamo itself.
 

Robert Watson

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VOC Member
I have found the trouble with pulling 12V from a 6v Generator is that (at least in this part of the world) running fairly consistent and long highway speeds with a headlight on requirement and other electrical bits the generator overheats and instead of a nice commutator you have a copper mouse nest..... I have done that twice....
 

Bill Thomas

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VOC Member
I was just leafing through some of the articles posted and wondered why people were attempting to rewire dynamos. 40 years ago I solved the problem of the lack of a generator on my Velocette by installing a Fiat 500 car generator. I then approached Dave Lindsley who put me in touch with John Gardner who made me a regulator/cutout to suit. This was very successful. I had an additional clip-on with a 55watt spot hanging wired into a relay switched dip beam circuit. The main headlamp had an E type Jaguar sealed beam unit. I could see at night!
When I tackled the Vincent engine I already had the standard Miller generator. Mr Gardener supplied his standard offering this time, in this one he limits the field coil voltage to 6 volts. Now I have no experience to report since shortly after completing the Norvin rebuild the winter was upon us and then I was sent to Saudi Arabia for work. (Insert usual long story of family, working abroad, paying for the kids)
The point being is that the Achilles heel of the old 6 volt systems was the vibrating contact points of the regulator. Mount such on a piece of vibrating machinery and it does not perform too well. In the diesel engined air compressors on site in those days the regulator box was rubber mounted to help it survive.
Whereas in fact electronically it is relatively trivial to design a circuit to regulate the voltage to 14.2v. The trick is making it bike and weather proof. This is where the JG unit scores being firstly designed by an electronics engineer and secondly it is potted inside a die cast box so it is vibration and water proofed.
I do not know whether JG units are still around. They were a straight forward substitution for the old box. Change the battery and the bulbs for 12 volt items and let there be light! No mods were required to the dynamo itself.
Some of us had trouble with the JG unit, Mine lasted about 100 miles.
Cheers Bill.
 

timetraveller

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VOC Member
The thing is Mike that things have moved on in the last 40 years and what you found acceptable 40 years ago has, with years of hindsight, proved not to be as reliable as one would wish. Over that 40 years there have been a lot of developments, Chinese dynamos, Altons, Walkernators and many more. With the modern need to ride with lights on all the time, to power flashing indicators and possibly heated clothing more power than can be extracted from the original dynamos is required. We all have our favourites and, as you will have read, there are people currently experimenting with alternative systems. Time and experience will eventually decide which of these ideas will prove to be reliable on the road.
 

Mikeant

Forum User
VOC Member
OK point taken, as you say life has moved on since I laid the Norvin up in 1977. I was fed up with 6volt electrics in my student days so I built a simple regulator that was featured in Fishtail at the time. It worked well on the bench but it was not mechanically robust enough to survive the bike mounting. I then heard about the JG unit which for me worked well on the Venom regulating the Fiat generator. When I get the Norvin running again we shall see if the other unit and dynamo are reliable. I would have thought though that these days possibly a 3 phase alternator with a diode pack and regulator as a modern car would be the way to go. I shall have to do some research!
 

Monkeypants

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Non-VOC Member
I have a Chinamo running through a JG on a Rapide
It's quite a good setup, although I've not used it much, only 2500 miles to date.
It puts out a bit more power than the Miller did on a JG 12 volt reg. Same thing happened to the Miller with 12 voltJG as Robert experienced with his 12 volt Lucas. Lots of copper wool!
The Chinamo looks more robust in construction than either the Lucas E3L or the Miller. I would estimate that it produces 110 watts.
Not on par with the version 4 Alton for power output or appearance, but still a compact looking unit that makes decent power. Back to brushes though, so that's another negative.

Glen
 
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stu spalding

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VOC Member
Some years ago a chap attended the Severn Rally with a Lucas E3L dynamo that had been rewound for 12v using the commutator from a Goblin vacuum cleaner. He reckoned that it balanced the headlight at 30mph. Does anyone know any more about this mod? Cheers, Stu.
 

vibrac

Well Known and Active Forum User
VOC Member
Some years ago a chap attended the Severn Rally with a Lucas E3L dynamo that had been rewound for 12v using the commutator from a Goblin vacuum cleaner. He reckoned that it balanced the headlight at 30mph. Does anyone know any more about this mod? Cheers, Stu.
I love that one stu! so many puns come to mind (or is that a sweeping statement ?)
 
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