Hi All,
A couple of years ago I bought a Guzzi GTW single, it needed some basic fettling as it had not been on the road for some unknown time, anyway before I got to go through the wiring and charging system I put a new Cyclon battery in the hollowed out battery in order to have a brake light in preparation for a vintage event
Day one went fine, next morning when I stuck the key in the switch and checked the brake light, and no light lit
I checked the 10 amp fuse and it was OK, so with no more time available that morning I rode on for the day a bit nervously if anyone was riding close behind..
That evening I pulled the battery, to find it all swollen and out of shape
, Thats that fkd I said
After the week long event I got time at home to go searching for the "fault"
It turned out that the dynamo must have woken up and after riding about for the day the cutout must have stuck closed
The battery discharged into the dynamo and burned it to a crisp, the wiring was not affected or the 10 amp fuse did not blow!!
Whatever the resistance of the dynamo was it was high enough to not draw enough current to blow the fuse and low enough for the wiring to handle ? but still cooked the dynamo????
As Marelli dynamo's are only 30W and secondhand ones cost a mint, as do modern replacements I fitted a Lucas 60w
as they are the same diameter and have the same shaft taper as the Marelli it was straight forward,
I made a plastic adaptor and a small bracket to fit the Marelli end cover onto the Lucas, added a DVR2 and new battery. All has been good since
John