Hi guys , my ammeter is reading 18 to 20amps when driving at 2500 rpm which seems high to me , it does drop on tick over to about 8amps , I have looked at Nicks electric info but couldn’t see how to adjust the amount of amp output from my dynamo ? Ignition light is going out as it should so I wondered wether anyone had a similar experience and found a solution.Thanks for any advice.Dave
Yes that does sound high Dave and could result in damage to the dynamo if this is an unmodified three-brush type, since that sort of current can overheat the winding and melt the solder connections to the commutator (assuming the ammeter is reading correctly that is). For a three-brush you need to adjust the brush position to reduce the current to around 8 amps maximum. This fairly recent topic covers how to do the adjustment:
Thanks for your prompt reply Bob , something to sleep on I suppose , hopefully I have not damaged the Dynamo in the process. The thread is very useful so will have a thorough check tomorrrow .cheers. Dave
Before getting too involved with this problem it would be worth checking the ammeter calibration is reasonably accurate. These units are very simple, rugged but not necessarily accurate. I went down the route of looking at the dynamo for a high charge rate only to find it was the ammeter. The easy way to do this is to connect a known accurate meter in series with the "D" connection on the dynamo and then compare the two readings. You are fortunate that the problem is a high reading, potentially more expensive if it is a low reading/output.
Thanks Roger , I repositioned the third brush today which seemed quite simple( which is a worry)! Rotating it 1/2 inch against the direction of the commutator seemed to reduce the output to around 10 amps however yet to try on the road owing to other non related faults with carbs affecting drivability meanwhile I will take your advice Roger and second check the ammeter.Thanks again guys . Dave