Wiring from scratch

[Martin Prior]

6 volt is fine and in good condition the original equipment does the job perfectly well. Don't complicate things unnecessarily.

[Bob Culver]

Often a staple topic, the straight adoption of 12v has been little canvassed recently. Provided care is taken to moderate the gross output and particularly the field current, many seem to have had success.With a Summer resistor can adopt a very low charge and rely on a smart bench charger fro optimum maintenance. Many seem to limit field current mainly by setting the 3rd brush. Few seem to have adopted old mechanical reguators; it has been suggested that these rattle the timing gears. I cannot see why the 3rd brusjh cannot be reatined so a huge field current would not be switched.

[mopetta]

i'm using one of those...

https://www.ebay.de/itm/Laderegler-6V-el...xydUJTOux-

[mk1-mark]

I have just completed this on our Special.

Having read all the problems that people have suffered with Dynamators, we decided to go with a 12V Neg earth system, but to use a reconditioned dynamo converted to 2 brush operation & a more modern regulator box, the work on the dynamo was carried out by Vince Leek, who did a superb job, as always.  The wiring for this combination was very easy & uses commonly available parts.

As has already been said a 6V starter will work very will with a 12V system, but the brushes will suffer over the longer term.  You will need to buy a suitable 12V coil.  I have found the British made Remax Coils to be far more reliable than a lot of others currently supplied.  The current crop of foreign made "Lucas" ones are absolutely terrible.

https://www.gsparkplug.com/remax-es5-ign...lb101.html

If you are wiring the complete car from scratch, it may also be worth thinking about LED lamps.  These are at least as bright as the originals, but consume about 1/10 of the electricity.

Good luck,

M

[RupertW]

Thanks all for the assorted information, quite a variation of views but gives me a good idea of the pluses and minuses of various systems and lots to think about. I have to say that the idea of converting the existing dynamo to 12v with a modern voltage regulator hadn't really occurred to me and could be the way forward.

[Malcolm Parker]

My saloon has a Austin 7 dynamo that was rewound for 12 volts, together with diode in the cut-out box.  It has been used regularly over 20 years and I have never had a flat battery.  The reading on the ameter never seems to move much but to be fair I don't do much night driving.  The first 12 volt battery lasted about 12 years and the second is doing well after 8.  As for the 6 volt starter, I changed it for another about 10 years ago but the brushes seem to last okay.  When I start it the starter motor rarely turns for more than two seconds, so the brushed aren't being over-worked.

[andrew34ruby]

As my seven came closer to being on the road over the past few years I had a choice of what to do with charging. The car was built with a dynamo to power up few lights, and low wattage headlights, in a world without traffic jams and stop/start everywhere. I considered the Dynamator, but it seemed a lot of money for something of unknown reliability.

I chose to put higher resistance field coils in the dynamo, do away with the third brush, and use diodes out of an old alternator in place of the cut out. Fitted a 12 volt battery and everything works. I intend to fit an electronic regulator, but at the moment I regulate manually feeding the field coils through a couple of switched bulbs. It works.

[mk1-mark]

This is the regulator I used.  Very helpful seller & much less expensive than a lot of the alternatives.

http://www.aoservices.co.uk/car.htm

[Nick Turley]

Hey Rupert
I am keen on sticking to the original system.
My box saloon 6 volt battery has lasted in good working order for 8 years (just changed it).
Cost now £65.
It is 80 amp hours - so you can run at a big discharge for a long time at night.
The secret is to look after batteries, I always leave mine connected to an Optimate when in the garage - great piece of kit.
The other thing is to set the charge rate low, then your dynamo will work reliably for many many miles.

[Zetomagneto]

I converted my Dynamo to 2 brush, no fancy new windings, just converted to 2 brush, and used this regulator http://www.aoservices.co.uk/car.htm

I have 12 volt electrics and all is well. I would say the engine revs have to be a bit higher than usual before seeing a charge but it was a cheap exercise that works.