Hi
As the Measham is fast approaching my attention has been focused on my charging and lighting systems i.e will i get round on one battery?
These are the readings recorded on the cars ampmeter, incidently I know the charging system has two settings M & D but what do they stand for? I was told 'D' was for winter night driving but why use the initial 'D'
I digress see readings below and I would be grateful for your comments.
6v system with LED lighting with recently fitted battery.
'M' setting no lights 1 amp at idle
With sidelights 0amps
With headlamps -3amps
No alteration to out put figures when revs increased.
'D' setting no lights 2 amps at idle
14 amps when revs increased.
With headlamps on -2 amps at idle
11 amps when rev'd.
Does this indicate adequate charging rate for this event.
Originally with dynamo correctly adjusted for safe max 8-10 net amps no load on ammeter thelater cars just balanced the original headlamps and prolonged night driving required care. see post about 3rd brush. Many cars had larger bulbs and net discharge so night use restricted. But with LEDs you have lots to spare.
Normally at idle always a discharge. Is the system part electronic, modified to 2 brush, or dynamo/alternator substituted?
01-01-2020, 09:51 PM (This post was last modified: 01-01-2020, 09:53 PM by Zetomagneto.)
If you have a switch with M and D it is a magneto switch panel.M = magneto, in the off position this earths the contact breaker, in the on position the switch is open circuit. D = dynamo, in this position the dynamo charges, you do not have a high and low setting.
You could have a coil ign switch with a mag switch face on it
Paul, my guess is you have a magneto engine? If so, the M position has the dynamo switched off, with only the mag working. The dynamo only operates when switched to D. On the face of it that charging rate should see you through the night, but I’d worry that the dynamo is working too hard. I’d turn the charge rate down to about 6 amps, and take a spare battery if you have one. You can always not use it, but if you need to.......
Firstly I would say that a steady charge rate must be no more than 8 amps if you wish the dynamo to survive. To reduce the charge rate the third brush must be moved away from the main brush, so that when the engine is at high revs the charge rate does not exceed 8 amps. It may well be that with LEDs all round 6 amps will be enough to balance the full lighting load, so reducing to this figure would be a good idea for long dynamo life. You should be able to identify the third brush, because it is the only one whose position is adjustable in relation to the others. Incidentally where are you in Cambs? I am at Cottenham, just North of Cambridge. If you send a private message with phone no I will give you a call.
Robert Leigh
On the earlier 4 pole dynamos the main brushes are at right angles, an arrangement not expected by most tinkerers familiar with other devices.
I presume the idle speed is fast as the dynams is continuing to charge with the cutout remaining operated.
