Dynamo on way out ?

[ianpallen]

the wire 'colours' potentially mean nothing; the usual convention is not universally applied.

For the third time; you have connected the lights in series when they both light up and your 'earth' wires are not 'earthed'.

Note also that one (or possible both) of your lamps will almost certainly have their own built in ground connection.

cheers

No, they were not in series. I tried this and they did not light up. This is why I noted the colours of the wires. The black wire is positive on both lights and the black / white is earth on both lights.

I have noticed with dynamos that the bulbs are opposite polarities. The body of the bulb is positive and the centre of the bulb is to the earth. To wire up the back light to the battery pack, I have had to put positive to the earth mark on the light casing and the negative to the positive.

My sons dynamo works perfect on all lights. We tried swapping the lights on the bikes as they are the same but with different dynamo bottles. his dynamo lights up my lights perfectly. I even done it where we swapped bulbs over incase it was a fluke, but his still light up both of my bulbs. My synamo would not light up both of my sons lights or bulbs in my lights.
I am working on it this morning still.

[ianpallen]

Ok, Been working on hte bike and I fully removed the wiring for the dynamo lights/ The wire for the front light went through the frame and had rubber grommets at the frame holes. The back light had the wiring going along the mudguard and it was pinched in the edge of the mudguard where it is turned under neath. There are a couple od places on the wire where the wire was warn through and this was connecting through the mudguard, so this was the circuit. The whole bike was acting as the circuit to the lights. This is why the lights worked with the 'earth' wire not connected to anything. The dynamo still will not light up both lights at the same time. Front still dim and back still bright.
I have checked the dynamo on my electric drill as a speed of 1200rpm. The dynamo is 6V, 3W. It goes up to around 10.56V when I put the head of the dynamo on to the chuck of my drill as if the chuck is the tyre of the bike (drill at max speed). It does produce 6V at a lower speed, so the dynamo still produces power. I cant see the wire touching the mudguard cause any drop in voltage as to only make the front light dim.
This dynamo has a plastic cover onthe tip of the 'wheel'. I had a bottle dynamo before which had a nut on the top and I could put a socket on my drill and spin the dunamo to show it working. I could not remove the plastic cover without breaking it off, so I left it on.

[Brucey]

OK that makes more sense. Dynamos do vary; some will drive more current than others and at lower speed, so perhaps that would be the difference.

I wouldn't expect any dynamo to drive a dead short and light bulbs up at the same time though.

BTW you can usually make some kind of drive coupling using a piece of garden hose; put a piece of dowel in the drill chuck (big as possible) slit the ends of the hose to make them wide enough and use a couple of jubilee clips to secure.

cheers

[ianpallen]

Good way of making a drive for a drill. I never thought of that way. I have two drills, one is keyless chuck which is a plastic / rubber chuck and it grips the dynamo wheel, the other is a keyed chuck and the teeth catch the wheel if I hold it just right.

The dynamo is now in the bits box. I am thinking of attaching it to a trailer or I might invest in one of those dynamo usb charger socket to charge mobile phones (if I can find one cheap enough).