Calling all electricians

So... The story of my battery not charging continues and I need your expert help. To start off I must warn you all that my electrical prowess stops at positive and negative leads on a battery.

The symptoms, I blow my inline fuse all the time, which I have figured out stops my battery from charging. I believe this happens on either ignition setting while riding. When it's blown the bike will still run on battery but when it gets low, it runs like crap due to my Boyer. It has never left me stranded though. A couple kicks with the ignition off and I build enough charge to start her up!

This morning I went to check on her having left the charger on all night, fuse is blown battery is fully charged but no light will even come on. I thought I had tracked the fuse problem to an oily connection at the Zener diode but it's still blowing.

So my questions are, should my headlight come on with a blown fuse and full battery ( 12.95 reading this morning )
Is a 20amp fuse the correct size
Does anyone have a guess where I should start on the blown fuses
And, I bought a 20amp toggle switch from radio shack, has anyone replaced there fuse tube with one of these? Would it be a good option in case you blow it on the road you could just switch it back like a circuit breaker in your home.

Thank you for any help you might provide

nortoneer850 said:

should my headlight come on with a blown fuse and full battery

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No.

nortoneer850 said:

When it's blown the bike will still run on battery

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That shouldn't happen either. However if the fuse blows, the electrical system will still be powered by the alternator output (and lights should continue to work while the engine is running).

nortoneer850 said:

Is a 20amp fuse the correct size

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If it's a continuous rated fuse, then yes.

The old Lucas fuses were described by "blow" rating, which is twice the continuous rating. If the original Lucas style "35A" glass fuse is replaced with any other type (blade fuse) then it should be one of either 15A or 20A.

from your description you need to look at EVERYTHING on the brown-blue wire with the 2MC blue capacitor being one of them and a bad zener. if you don't know how to use or have a multi meter than disconnect EVERYTHING on that wire to see if the trouble goes away. if so than start hooking up one thing at a time till the fuse blow's and you will find the trouble. if it still blow's with everything unhooked than you need to look for a chafed wire. if you do not turn on the key you could even go to a smaller fuse so it will blow faster.

nortoneer850 said:

This morning I went to check on her having left the charger on all night, fuse is blown battery is fully charged but no light will even come on. I thought I had tracked the fuse problem to an oily connection at the Zener diode but it's still blowing.

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I would not put a switch in place of the fuse. If there is a problem, which it sounds like, you risk a fire. A 20A rated switch is not a fuse. It's rated to carry 20A, but it will let much more pass for quite a while, or until the fire starts. Get yourself some help.

Dave
69S

As Dave said, don't replace your fuse with a switch...bad idea. Connection for brown with blue stripe wire are battery negative pole, Zener diode, blue can capacitor, power take off plug and ignition switch. As mentioned I would start by disconnecting the Zener, blue can and power take off plug. Turn on the ignition switch. If the fuse doesn't blow start reconnecting each one at a time until the fuse does blow. Once you find the offending circuit go down the wire to see where it is shorting to the fame of another wire.

Check and clean the surfaces of all your grounding points. There should be 4 of them, possibly 6.

What you can safely replace the fuse with to track down a short is a 12V bulb (tail light, turn signal, etc), as long as there a short in the system it will glow brightly, when the problem circuit is disconnected it will go out or only glow dimly...replacing the fuse with a switch is a recipe for disaster as was said. A bulb will limit current to only a few amps. No insult intended but you should probably get help from a friend with more electrical experience to help you fix this, sounds like there is a high potential for distressing smoke in this case

If there is a short bad enough to affect the path to the Boyer, you can put a plug on head and listen/watch for it to spark with key on while tugging jerking wires/connections. Also can do after dark for other spark short locations. One weak link I've had do similar to yours was a bad tail bulb earthing strap shorting to power side. Boyer trigger wires will go next if not already upgraded secured. These trigger wires failure don't blow fuses though just your mind on mystery misfires.

My money is on a chaffed wire causing a short. You don't need to be an electrical expert to find a chaffed wire just lots of patience. I had one on the wire that goes to the lamp in the speedo it would make contact with the headlight shell and pop the fuse found it by dumb luck it was the first place I looked. The fuse is doing it's job and is keeping the smoke inside the wires and not letting it leak out.

You need to get a continuity meter . or a bulb on a few feet of wire ea side . Start seeing were the current isnt . SMELL for ozone from escapeing Ergs .

look for flattened / chaffed wires . rectifyers Er arnt entirely um reliable ( Lucas ones ) then theres the hardened insulation cracking at the alternator at the chain case .

The wireing isnt to hard to do from scratch , and replacement looms at $ 100 odd , good value . Pretty much ' join the dots ' to fit one .

Bulb holders can short out , if its something like it blows when the stop light hits , sometimes in conjuction with a differant function , causeing a short .

I dont expect prehitoric electrical componentry to function , unless stripped and cleaned .
However , spaying full of C.R.C. will move the spiders out and a airhose get rid of the webs .

Check ALL the Spade Connectors for a firm slideing fit .And terminals . All pretty basic , if youre thorough .

Thanks for all the replies as always, you sure are a good crew to know. I'll start searching wires and give up the thought of putting that switch in. See ya on the road.