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Misc Charging system not working

highbury731

Well Known and Active Forum User
VOC Member
#1
I was most of the way home last night when I noticed that the lights had gone out (the bike's, not mine..). On checking, there was a faint glow. Battery (two Cyclons in parallel, 6V) run down, due to non charging.
The bike is in the shakedown phase, and was off the road for 30 years. I think the Lucas dynamo needs 'flashing' to wake it up.

I think that the method for flashing is to disconnect the dynamo from its drive. Connect battery earth terminal (in this case, + ve) to the body of the dynamo, and the other terminal to the D terminal on the dynamo, and let it motor for a few seconds. Is that correct?

Paul
 
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greg brillus

Well Known and Active Forum User
VOC Member
#2
If the battery is buggered you should fix that first or else the generator will be working too hard to charge it before it can supply anything else in the system. You will need to flash the field terminal on the generator, green wire, may need to clean up the commutator with a bit of emery tape held against while its running and clean off with a dust gun, or clean rag.
 

BigEd

Super Moderator
VOC Forum Moderator
VOC Member
#3
....... I think the Lucas dynamo needs 'flashing' to wake it up.
I think that the method for flashing is to disconnect the dynamo from its drive. Connect battery earth terminal (in this case, + ve) to the body of the dynamo, and the other terminal to the D terminal on the dynamo, and let it motor for a few seconds. Is that correct?

Paul
Examples of how to flash positive or negative earth systems at the link below:
Flashing a dynamo
 

chrislaun

Well Known and Active Forum User
VOC Member
#4
If you haven't had the dynamo to bits there's a good chance the commutator needs cleaning, I have found this is the most common fault, even if they are in use the surface can "glaze"if the dynamo isn't doing much.
A really in depth analysis of lucas dynamo's, how they work, what goes wrong, testing and how to fix them is on a site called "Matchlessclueless"
 

highbury731

Well Known and Active Forum User
VOC Member
#9
If you haven't had the dynamo to bits there's a good chance the commutator needs cleaning, I have found this is the most common fault, even if they are in use the surface can "glaze"if the dynamo isn't doing much.
A really in depth analysis of lucas dynamo's, how they work, what goes wrong, testing and how to fix them is on a site called "Matchlessclueless"
I followed the excellent instructions on this site, and flashed the dynamo. Before running the engine up, I charged up the battery using a local garage's high power charger. It had no 6V output, so I rewired the two Cyclon batteries in series so that it became a 12V item. Both read 6.5V after an overnight trickle charge.
Following the excellent instructions on the 'Matchlessclueless' site, I checked the dynamo output, which read 4V at idle and 14V at a fast idle. Very good figures indeed - so good that it makes me think that the dynamo will cope very well if I fit a 12V regulator.
All I need is a working ammeter, and the system will be AOK.
So that amounts to a long-winded thankyou for pointing me in the right direction
Paul Standeven
 
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