12 volt

[Tone]

Can someone please tell me what you have to do to change to 12 volt? Do you get rid of the regulator? do you do anything to the dynamo etc? A list of new bit's you need would be a great help,Cheers Tone.

[groily]

Tone
The easiest/cheapest way to do it is: Buy a 12v battery and 12 v bulbs and put them in. Get rid of the mechanical regulator if you have it and get . . . a DVR2, which can be ordered in Positive Earth (probably yours is?) or Negative. (Other makes also work fine - I'm just biased through happy experience.) DVRs come with the option of running in 6v or 12 v mode - all you do is NOT use one wire in 12v mode and the instructions are such that you couldn't screw up. But they are sensitive to the earth, as stated. A so-called 6 volt dynamo will easily chuck out enough to run a 12v system, especially if you have a belt drive conversion which gears the dynamo up about 10 per cent. But it will need a few more revs then before to get to the point where the electrical load is balanced by the dynamo's output.

Or you could have the dynamo rewound with finer wire for the armature and field - plenty of options there from all the usual electrical specialists - armatures about 65 quid, field coils about 25-28 or so. Plus the new regulator - 40-ish.
Some modern regulators require(d) the internal wiring of the field coil and brushes to be changed, is the only footnote to add. Not sure if any of them still do, but JG did for a long time.
Good luck. Best advantages of the change are lower current for the power (watts) so fewer stray amps running around, less sensitivity to bad connections in the harness owing to the oomph of the 12v compared with the 6, plus it's so much easier to buy 12v bulbs. Having said that, my A10 is the only dynamo bike I have still running at 6v . . . and it's fine too.

[Tone]

Thanks Groily, very helpful, the DVRZ you mentioned where would I get one, is there a trade name for it?also would I have to change the light fittings?

[Brian]

These things are brilliant. Here's a link to Mikes website.

http://www.manortec.co.uk/dvr.htm

[fido]

For some years my A7 has had a car type mechanical reg. box, the sort used on early Minis, Moggie Minors etc before they introduced alternators. I fitted this when the electronic unit went wrong and its worked fine, no adjustments needed.

[groily]

No need to change light fittings Tone if you get the right bulbs. For them, no-one is better than Paul Goff (links all over the place in electrical threads here). All types of fitting and bulbs, including halogens with old twin pole connections, etc etc. You'll have no trouble unless you've got something really weird up front..

Re the old-style car regulator Fido, Yes, I've heard they work fine too. But isn't the box rather large, as doesn't it also contain the current regulating stack, redundant on our toys? Not that it matters if it'll go in the toolbox/under the seat! Bit hard to get these days though, what with the shortage of scrap-yards of the old sort where these things could be got for a pound. Funny thing, which supports your point, is that I never ever had a car CVC fail in umpteen gazillion miles in old Minis and Moggies . . . can't say the same for their 2-wheeled cousins!

[beezalex]

The only potential issue with the car regulator is that its current limit is much higher than the original or the electronic regulators.  This would only be an issue with a very low battery while also running lights at high revs...not something you would usually encounter.

[fido]

It's a voltage regulator, not a current regulator. The charge voltage for a small motorcycle battery is much the same as that for a large car battery.

[Triton Thrasher]

The only potential issue with the car regulator is that its current limit is much higher than the original or the electronic regulators.  This would only be an issue with a very low battery while also running lights at high revs...not something you would usually encounter.

Does the original regulator have any current limit at all though?

[beezalex]

Most automotive mechanical two and three-coil regulators include current regulation as well as a current limit.  This prevents a) overcharging the battery and b) drawing too much current from the generator when demand and speeds are high.  I can't say for sure the original MCR2 regulators had this as I've never seen a schematic or functional description of one, but all of the Bosch and other Lucas regulators I've seen have current and voltage coils in the regulating coil to limit the amount of current coming from the generator as well as the voltage.  Usually, the current regulation is matched to the current capacity of the generator.

[fido]

Yes, the car type regulator is capable of controlling current but in this case it will never act to restrict the current because the dynamo will never reach the output level where it would come into force. Effectively, the current is not controlled, as is the case with the original 6 volt regulator.

[groily]

As Far As I Know, no m'cycle mechanical CVC unit from Lucas has current regulation built-in. Car ones do, and as Fido says, the E3L will probably never get near the output in Amps that would make it regulate (even with a flattish battery). So that bit of it is redundant. The old dynamos on Moggies and so on were rated 20 Amps; ours are 10.
But they all, whether for cars or bikes, allow a discharge into the field from the battery at low revs. DVR2s don't - which is one of their very best features . . .
For my money, call Mike and get something foolproof that works, fits anywhere and was designed with our machinery in mind!

[Tone]

Groily, I've had a good look round and I cant find anything about Paul Goff, has he got a web shop or some way of contacting him? Cheers Tony.

[trevinoz]

Fellows I think you will find the Lucas motorcycle regulators do have current regulation via the heavy winding around the "regulator" coil. Heavy current in this coil will attract the regulator armature and open the supply to the field coil.
In fact, there are 2 different MCR2 types with differing number of turns on the regulator, one type for the E3L and the other for the E3H, E3N etc.
 Trev.

[fido]

My apologies, you are correct, Trev. I just had a look at Service Sheet 804 and it does mention the series winding which restricts the voltage in the case of high current. I think my 1948 bike would originally have had the BR107 regulator, covered in service sheet 804A. The text of that section does not mention current compensation but the circuit diagram shows the same series winding going to the A (output) terminal.