I like to keep it all very simple and stick with the original 6 volt system.
Saving a lot of issues using standard parts and setup.
The batteries that we have now are super performance.
Dynamos that are rewound with the newer wire are much better as the wire coatings are superior.
The trick for me with the dynamos is to keep the charge rate down to a sensible level, this seems to give a very reliable piece of kit.
I do not worry about a discharge with all lights on, as I am using like most of you a 80 amp hour battery.
How long do you need to drive in the dark ?
I drove three hours fully light the other night - enough for me.
And are your reflectors beautifully re silvered with the headlamp bulbs focused ?

Location: The Centre of the Universe

Thank you all for all help with my problem
With regulator is best to use
But i am a lot "more" confused than before
As i have had armature rewound / field coil and from 6 volt to 12 volt
Can i just buy a new regulator electronic or not And it will be up and
running, And were to buy one !
Help "Just going up the tower (i live in Blackpool)getting ready to
jump off

Location: United Kingdom

John is your dynamo still three brush or rebuilt as a two brush? If two brush the electronic regulator can,as mine is be fitted out of sight under the dash.The existing wiring can be cut within the harness to give the appearance of being original.

Location: Piddle valley, Dorchester.

Hi Paul Thanks for your comment's My dynamo is 3 brush
I live in Blackpool
Regards John.

Location: United Kingdom

Hi All,
Update on my dynamo sager,
I have had it wired to a 2 brush now
to my regulator that was there
"Good News" Its all working with a good charge
Very happy I am in love with my car again.

Location: United Kingdom

Now that my Forum access is recovered or restored, the following is a repeat of the essence of a reply emailed to Malcolm, for the possible interest of others.

No matter how carefully I prepare comments, seem to be misinterpreted, or offend someone! I have never said any arrangement wont work, just that some simple conversions often claimed either defy physics, or some key factor is not mentioned, or some feature unknown to me and not explained by others operates to avoid trouble.

I note Vince operates 12v with no field limit resistor, but winds back the third brush. If the field limited to say 6v the situation is much as original and the field should be OK. The added virtue that there is no power wasted, but without some exploration with a meter it is difficult to know just how much power is being fed to the field, whereas a resistor guards against excesss.

Vital essential provisos are often not mentioned which is why conversions are often so confusing. Some claim to connect the original 6v field directly to the 12v output and live! Power approaching the full original dynamo output would then be sunk into the field winding!

I think several readers confused reference to the field winding and the watts absorbed by it, with dynamo output. With the field, all watts supplied to it go as heat of the winding and any resistor, if any.
The armature situation is different from the field, the watts input come from the mechanical drive and the watts output is dissipated externally. It is just the armature current squared x armature resistance which produces damaging armature heating watts. Thus whether 6v or 12v heating is much the same for the same current, whereas the output watts is doubled, the whole basis of power output increases with 12v.

The total power generated is near output volts x gross armature current, the latter 2 amps more than the no load ammeter reading (coilo cars) plus field current, say 13 amps, about 90 watts at 7v. Probably needs twice this in mechanical watts to drive. If all stepped up to 13v with the same amps the power to drive also more or less doubles, which the gears will certainly notice.

I know this repeats points others have already made but it is all together.

Malcom’s simple Cornwall scheme and as advocated by Steven Hainsworth works reliably because field current is substantially as original, and the dynamo output amps are kept modest.

Bob Culver

Location: Auckland

not about regulators . but have just seen your youtube clip of silver 7 special .i think i now own that car AOK --- could you email me and perhaps answer a few querries for me
many thanks
clive

Location: United Kingdom

not about regulators . but have just seen your youtube clip of silver 7 special .i think i now own that car AOK --- could you email me and perhaps answer a few querries for me
many thanks
clive

Location: United Kingdom

Very well said Nick, I am completely agree with everything you say, and with the addition of LED the reasons for converting to 12v simply no longer stack up, I never really felt they did in the vast majority of cases either. I have always had complete reliability with 6 volt systems, but then I have only been driving Austin sevens for 30 years or so and still may have not have discovered all their failings!

Location: NZ

All very true. The problem is owners used to adjust to more than meet the original lamp load and now try to match larger lamps, cooking the dynamo. With original wattage lamps and precautions at lengthy traffic stops the 1930s cars could be driven any distance at night.
A characteristic of the unregulated system is that as voltage falls, so does dynamo output, so can drive on to trouble. If caught far from home with an inadequate system, can disconnect one lamp! May get better lamps with lower wattage bulbs!

I dunno about pre 1933 cars, which Vince will hopefully answer. But If you look at John Cornforths Dorset Club circuit diagram, if the wiper and petrol gauge are directed to earth somewhere else, then the lead from the cutout E serves only to earth the shunt voltage winding. So the extra resistance can be placed externally between the E terminal and earth. The resistance is given as 30 ohms and the added should be the same (or 33, more available).

If no resistor is added to the field circuit, esp care necessary to keep the third brush as retarded as possible for required (modest) output.

Note that the 10 amp or whatever net output rating of the dynamo does not refer to 12v operation, when a lot of hidden current may be disappearing into the field !

Location: Auckland, NZ

Frightening fact I have been driving mine for 50 years!!!!!!

Location: The Centre of the Universe

As I said Nick I am a relative newcomer so still learning

Location: NZ