Battery or earthing problem?

[trevinoz]

Dave,
            I have the feeling that you and electrics don't mix well.
Is your regulator set for 6 or 12 volts?
If your 6v light is fine and 12v not, it seems as though you are regulating to 6v.
What does your multi-meter show?
        Trev.

[chaterlea25]

Hubie,
what wattage 12volt headlamp bulb are you using? are you using the sealed beam unit mentioned??
A 60/55 watt bulb is too much for the poor dynamo and it will fail again given time (not long in my experience)
The symptoms you describe are fairly typical of a 6-12 conversion using an undersize battery
the bigger battery will hold the voltage up longer when the dynamo is not balancing the load!
If the voltage dropps too much the reg may see this as a fault and shut itself down (not privvy to the internals of the vreg)
Get a decent sized battery 8AH upwards, you can fit up to a 14AH battery by flattening down the tabs on the bottom of the battery case!
You can get 40watt H4 bulbs and a H4 reflector fairly easily or a 12 volt prefocus bulb 35/35w to fit the old reflector unit, or even a halogen bulb to fit the prefocus unit.

Lastly 

A toothed belt  drive setup that increases the dynamo speed 10% is available from SRM, not cheap but a very nice piece of kit!!
I am not a fan of the vee belt kits as the belt needs to be fairly tight and any oil escaping from the inner case will also make it slip

Regards
John O R

[trevinoz]

John,
            With 12v conversion, 80watts output is achievable.
At least with my rewind it is.
                                            Trev.

[chaterlea25]

Hi Trev,
80 watt is peak output and not continuous ,
As far as I am aware the limiting factor with the dynamo is the metal losses and only one field coil!
the "12" volt armatures and field coils have more turns of lighter gauge windings to give an improved output at lower revs
I have repaired several converted dynamo equipped machines that had 60/55 bulbs fitted,
If 80 watt continuous could be extracted from a lucas dynamo there would be no market for Alton alternators!!!

If you have a method of extracting 80w continuous please tell us how? and we will all go out dazzling rabbits!! LOL!!

Cheers
John

[trevinoz]

John,
             I admit that I have not road tested my dyno. I loaded it on the bench for quite a while and had no over heating.
I reckon a safe load would be 60/55w headlight plus other lighting.
I wound the armature with 0.7 mm conductors instead of 0.8mm. Originally it was .032"
I only use my bikes for club runs now and very rarely have the need for lights other than brake lamp.
Maybe one day I will fit the 12v dyno or try and find a guinea pig locally!
Trev.

[Hubie]

G'day all,

To clear the air, what I had done was to change to 12 volt globes (35 watt for the headlamp) and cut the green wire on the vreg II to change it to 12 volt and fitted a 12 volt battery.  No change was made to the dyno.

What I have now done is to put in a new 6v battery (13 amp hour), put all the 6v globes back in (25 watt halogen globe in the headlamp) and reconnect the reg wire to switch back to 6 volt.  If it don't work, then the dyno previously dying must have stuffed the reg and I will replace it.

Will report back with result soon.

Cheers,

Dave.

[Hubie]

New battery in and clobes changed, ammeter showing nearly -8 amps with headlamps on, revving reduces it but not to zero.  New regulator purchased.

[trevinoz]

Dave,
              What is the voltage you are getting across your battery, with and without the lights on?
With the engine running, of course.

   Trev.

[Hubie]

Hi Trev,

Battery sitting static is on about 6.7 volts, motor running once the reg has kicked in is about the same.  Turn on lights and it is on 6.6.

Cheers,

Dave

[trevinoz]

Seems a little low, Dave.
Trev.

[Hubie]

Hi Trev,

It's a new battery, so I will give it some charge tonight, I just chucked it in the bike once I put the acid in it to see how it went, the lights are good and strong but boy does the ammeter needle tip to the negative!!!  I have the 21 tooth sprocket back on the bike and the needle moves fine but the amps are way down with the headlamp on.  As I've mentioned, i have a new mechanical reg on the way (got it at a very good price) and will see how it goes.  I am thinking that the reg is not working properly.

Cheers,

Dave.

[trevinoz]

Dave,
           With the headlight on your ammeter normally would only be just showing a charge as the generator is supplying the headlight.
What wattage headlight are you running? Should be 30/24W on a six volt system.
Trev.

[Hubie]

I have just installed a new MCR2 regulator and there is a massive difference in the charging.  Only a small amount of revs are needed to bring the ammeter to zero or above with all lights on.  Should I be reading in the negative at idle with the lights on?

Either way it is a matter of adjustment as the reg was definately the problem.

Almost there.....

Cheers,

Dave

[muskrat]

Good to see you finally got the better of it
Cheers

[groily]

At idle the cut-out is probably open so the dynamo is not connected to the battery - thus the ammeter will show the full load of the lights as a discharge. That's fine and normal.
If your tickover speed is slightly higher than cut out speed (the battery still being connected to the dynamo across 'D' and 'A' on the MCR2), then there will also be a discharge because at these modest engine rpm the dynamo doesn't produce enough to balance the load.
If your ammeter shows zero or better at lowish revs while riding along with all loads on- say 35mph in top depending on gearing -  you're sorted. Hope so - you deserve it after all the hassle!