Blowing the Fuse

robot · Post by **robot** » Fri Apr 25, 2008 4:27 pm

My lightweight has been converted to 12V. The circuit is protected by a 35amp fuse. When riding out, after about 10 miles or so the fuse blows. The 'bike still runs due to the 6 coil arrangement - and the ammeter shows a permanent 4 amp charge with back to zero with the headlight on. I replace the fuse and all is well - until after about 10 miles!! Can't be lighting circuit as lights not on when it happens. Any suggestions, dear folks?
Robot

AJS650 · Post by **AJS650** » Fri Apr 25, 2008 4:32 pm

dear boy only ride in day light that will solve evrything

pto · Post by **pto** » Fri Apr 25, 2008 5:40 pm

Where in the system is the 35amp fuse fitted?, Once the fuse has blown there should no charge thru the ammeter, there is a diagram of a 12v light convertion on the website, it may be a good idea to check it against yours

Don Madden · Post by **Don Madden** » Fri Apr 25, 2008 5:43 pm

I have had mysterious fuse failures caused by poor fuse contacts, which will heat the cap of the fuse enough to melt the link. The indication is the link parts at the cap, out of sight, not in the center, so the fuse still looks good.

A slight overload of a fuse causes the link to melt. A major short usually causes to fuse to vaporize leaving metal & black spattering on the inside glass.

And a 35A fuse is very large, risking overheating of the wire harness with melting of the insulation. Do some checking of the circuits to find the problem.

Most AMC bikes I have had connect the battery to the horn directly & from there to the stop lamp switch, not to the ammeter circuit, so any shorts there will not show on the ammeter. I suggest you check them first, especially where the stop lamp switch wires may be chafed, or under the rear mudguard.

Cheers, Don.

robot · Post by **robot** » Sat Apr 26, 2008 11:18 am

Thanks you all. I'll check everything over - and the fuse failure occurs in daylight as it's not been ridden at night, so there!

AJS650 · Post by **AJS650** » Sat Apr 26, 2008 12:29 pm

[quote]
Thanks you all. I'll check everything over - and the fuse failure occurs in daylight as it's not been ridden at night, so there!

Don Madden · Post by **Don Madden** » Sat Apr 26, 2008 5:48 pm

Laugh now, Anne, but when the days grow shorter but the weather is nice it is hard to give up & head home. Especially when your mates form a blockade at the Pub door.

Cheers, Don.

AJS650 · Post by **AJS650** » Sat Apr 26, 2008 8:04 pm

quote:
Laugh now, Anne, but when the days grow shorter but the weather is nice it is hard to give up & head home. Especially when your mates form a blockade at the Pub door.

Cheers, Don.

one day don.... i will get out there.... i have faith for this summer

Don Madden · Post by **Don Madden** » Sat Apr 26, 2008 8:40 pm

If you manage to come out, I'll get some friends together to form a blockage & keep you from leaving.

Cheers, Don.

model26 · Post by **model26** » Sun Apr 27, 2008 1:59 pm