After the battery went flat again (had been more than a month since this happened before), I decided to overhaul the connections in the charging system as a first step. I reviewed the current 'universal vintage bike rectifier' and it's connections and decided they needed a clean up. As the rectifiers were only £5 I thought I would replace that while cleaning the connectors.
I started the bike and revved it - the ammeter stayed as discharging. I reviewed my connections and saw one connector had fallen off. I pushed this on and tried again. The bike ran briefly then stopped and didn't want to run much at all. The inline micro / mini blade fuse I had put in the positive wire from the battery to isolator switch had blown. It was marked '30'. Most of the wires on the bike don't look like they would take 30 amps - am I really generating 30 amps or could I be just shorting the battery ? The bike is on 6 volts. The battery in a meaty 12A one that was meant for a Honda CD200 (electric start).
If a 30 A fuse blew, there…
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I'm thinking a short circuit…
I'm thinking a short circuit is most likely now - I'll take my time a and work through things. Good job I did fit a fuse!
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Fuse-rectifier etc
30A fuse is a bit on the high side 25A at most. To reiterate what is else where on the Forum. The fuse is to save the Electricity in the battery getting into the wiring and the bike and causing a fire. Nothing to do with generating 30A. (you are lucky to generate more than 10A) With above Post there is no indication of what the bike is or more importantly alternator/coil ignition or Mag/dynamo. As we have a 'universal vintage bike rectifier' (what ever that is) we must assume we have alternator/coil ignition. I ask why is the fuse in the Positive? Surely the bike is Positive Earth, hence fuse would be in the live (Negative). But working through fro the Short Circuit is needed. Stop light wiring and switch is a good starting point and any area you have just been 'fiddling' with ie inside headlamp.
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It is alternator / coil…
It is alternator / coil ignition. I looked at it again today in proper light and could see what had happened when I had rearranged the wiring and battery the other night - the negative terminal of the battery had contacted an earthed (positive) area. My fusing arrangement seemed to work in the arrangement I have - it blew when there was a short circuit. I've now rearranged things again and put in rubber insulation around the battery and box area. Used the bike for about 10 miles today and the ammeter stayed steady deflecting one 'notch' to the right when running. I've been doing some 'homework' on alternators and charging systems - I visited the workshop of a local enthusiast who had contacts who re-manufacture alternator rotors and zenier diodes and saw how the things might go together. I haven't looked at what sort of rotor / stator I have yet but understand there may be issues fitting later rotors onto '58 Dominator cranks.
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Good running but...
Nobody re manufactures zener diodes for British bikes. Fitting the later (74mm dia) rotor to Dommies is NOT an issue, all the cranks are 3/4 dia same as all Lucas rotors. The 58 Dommie would have had a 70mm dia rotor originally, So if you need a new rotor you have to have a new stator as well ie both parts need to be 74mm (OD rotor). All the lightweights have 31/32 cranks for the Wipac rotor, but that is another issue.
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Main fuse in a sole return…
Main fuse in a sole return wire at the battery has slight advantage, unless you want some components to run without a fuse. The popular arrangement of putting the main fuse on the live side is good enough though.
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Just to clarify
Just to clarify the fuse situation, the fuse MUST be in line with everything (except any starter motor) on the motorcycle. Time and again I have several wires to either battery terminal this can very easily bypass any fuse so the answer is a disaster. I have always advocated a SINGLE wire to each battery terminal and the fuse in one line. Then a lot of unnecessary faults are obviated.
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Regarding Zener diodes - I…
Regarding Zener diodes - I believe these are diodes that a bought in (e.g. SOLID STATE 1N3313B - not sure if that is exactly what is used) and then fitted to the original radial metal thing that Triumph bikes have between the front forks
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I don't know the exact item…
I don't know the exact item that is being fitted, but I understand that is the approach - take an existing off the shelf component and fit it to the finned heat sink housing..
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Consolidate all your…
Consolidate all your electrical faults into one big one!
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If a 30 A fuse blew, there was a short circuit that shorted the battery.
Can’t say I’m following the other stuff.