Hitchcocks Forum

Dear All,

I'm back again with continued charging problems... I have installed a new Lucas Single phase 12V 120W 2 wire stator and rotor, Lucas Reg1 120w rectifier/regulator, new gel battery and installed a wiring loom to the diagram shared in the link below;

https://drive.google.com/file/d/1GXNfvI ... sp=sharing

After a top-end rebuild the bike runs beautifully, except after 4 miles when the battery runs flat, sputters to a stop, and is difficult to start again! The ammeter dips below 1/2 way with pilot lights switched on, and remains down once they are switched off. I have also noticed the ignition coil gets very hot when the ignition is switched on, but the bike not running. I have switched out the ignition coil to test, with the same result.

I have tried a few basic tests with my multimeter on the battery, and blown the Reg1 by removing certain wires (which I replaced), but still no luck.

If anyone has any thoughts, suggestions or similar issues, I would be glad to hear as I'm at a loss as where to look next!

Many thanks

I'd start by doing a couple of static tests looking for current leakage, shorts and anomalies. So leakage, disconnect the coil, ensure the lights are off and turn the ignition on. If the ammeter moves, you have a problem, disconnect componants one at a time until it zeros and you've found the problem. You may want to use a more sensitive ammeter in series with the battery positive for this test. Most multimeters will have a 10A setting which you may need to put the probes in a different socket for. Nothing on your bike should be exceeding 10A.



Next I'd try to find out what the heck is happening with your lighting. An ammeter moving halfway seems a huge swing, is there a short on your pilot lights? Why is it apparently "latching" when the pilot lights are on? So with the coil still disconnected and engine off, try the pilot lights on (so you have what, 2x 5w?) should be drawing in the vicinity of 1A. When you turn it off again, it should go back to zero amps. If it doesn't, I'd suggest you have a problem with the light switch. There are bulbs in the circuit so it (hopefully) shouldn't pop the meter.



Ok, next thing, to totally flatten a battery in 4 minutes, there is a huge current draw. So, if the above all checks out, that kind of leaves either a short in the coil or a hugely duff reg/rec with some sort of dynamic earth leakage. Here you may need to take a conscious risk, how many amps is that coil drawing? If it's more than 10A you could pop your multimeter fuse when you power it up (gives you an answer all the same). It's definitely a 12V coil?



Maybe worth checking the charging phases for a short to earth too? There should be no continuity between either phase and earth.

OK, stinkwheel's got his reply in first, but I think we have similar concerns.



A 12V rewire with new alternator and reg-rectifier shouldn't end in tears, especially as yours is a simple set-up with no indicators or electronic ignition to worry about. If nothing else, this is a good advert for magneto ignition...



Let's have a think about the wiring first.



From the reg rectifier you connect the -ve to earth on the frame and the -ve battery terminal. The +ve red wire goes to the +ve ammeter terminal with wires back to supply power to the light switch and the ignition switch. From the other ammeter terminal you want a wire to the battery +ve terminal via the fuse and another one to the horn. That's pretty much it for the charging side.



After that, wire up the coil and points from the ignition switch, with the feed to the rear brake light switch off the +ve side of the coil and from there to the brake light.



That leaves the rest of the lights to wire in. Wire up the pilots to the pilot position, the headlight supply to the dipswitch, the rear and speedo lights to their position. Main and dip wires to headlamp bulb, and apart from any extra earth wires needed, connect the horn that's it.



I have several observations/questions:



1. Ref the positive wire to the ignition coil on your diagram, it looks like you have it joining the positive wire from the reg/rectifier instead of coming straight from the ignition switch.



2. What switch gear are you using for lighting and ignition? Not sure how you're managing your pilot/headlamp operation as you diagram has the pilots shown twice;



3. Even new reg/rectifiers can be duff, shorting out internally;



4. Any evidence of short-circuits in the wiring anywhere?



5. Is the ignition coil new as well?



Hope you can get this sorted.



A.

Like the others, I'm suspicious of the reg/rec unit, your symptoms sound like overcharging and then discharging, the reg/rec is the obvious suspect. I did a Google search for the 'Lucas Reg1' unit and it seems to be a quite high capacity unit sold for cars and special builders. While I don't think it would over-charge just through being a high capacity unit I'm not convinced it's suitable for bike use. That's my tuppence worth! And yes, the coil will get warm when ignition is on but not running, if it's too hot to touch there may be a problem.

REgards, Mark

I noticed the comment about the coil overheating, too. It will get warm in normal operation and shouldn't get too hot if the engine is running (when the points are open the LT supply to it is effectively switched off, basic principles). However, it's not good practice to leave the ignition on with the engine stopped and the points closed, so it might just be normal. However, if the coil is badly overheating I'd suspect it might be a 6V coil instead of a 12V one. Or, is there a dead short via the points condenser or elsewhere?

(I take it that you're aware that if the contact breaker clearance is set too tight the dwell angle will be reduced, which means the LT side of the coil is powered for longer than designed for. I doubt that is your problem though).

Your bike might have a faulty lighting switch causing a short to earth. My 350 Bullet Electra has Minda switchery. I have noticed that occasionally of late the pilot lights stay on when the lighting switch is selected OFF. I think this must be sticky contacts; I'll get round to looking at that, but for now cycling the switch a couple of times sorts it out.

Zelda - Your bike has FOUR pilot bulbs ?

" ammeter dips below 1/2 way " is a discharge of how many amps ? Suggest you measure this with a (reasonably accurate, reliable) multimeter.

Battery runs flat after 4 miles (Stinkwheel, that's MILES not MINUTES, and not TOTALLY flat, either) tells us it probably ain't being charged but very little else.

Why have you wired the bike NEGATIVE earth, and what was your reason to replace what seems virtually the entire charging system ?
More info. please, if you want folks on here to help you.......

Apparently there was a move away from positive earth systems to negative to reduce chassis corrosion in cars, I believe all modern vehicles are now negative earth. Converting to 12V allows for a simpler wiring loom. It's possible(!) that some or all of the original electrics were knackered after 60-ish years, hence wholesale replacement.



Once Zelda has had a chance to digest our comments some more information indeed would help.



A.

Adrian - I am fully aware of the changeover to negative earth on vehicle electrics - but as Zelda's bike is neither a car nor a "modern vehicle" in any sense, I ask again for his reason for this change. (My feeling is that a polarity change would make it way easier to mess things up if following a wiring diagram, particularly one as sketchy as that in the o.p.)

If the original electrics are boogered after "60-ish years" it sounds like they may have fared better than the new replacements !

If Zelda has fitted the reg/rec I think (s)he has it looks to be intended for car use and may only be available in neg earth? Unfortunately I can't find the listing now to check!

REgards, Mark

I've had a look at Zeldas wiring diagram.... Zelda please tell us your bike is not actually wired up like that? The regulator/rectifier you have can be wired for positive or negative earth. I just cant get my head around your wiring diagram (that's if you've drawn it correctly?).. The only time I have ever come across a "hot coil" is when one is failing OR a wrong one has been fitted. What kind of ignition are you using? Points? Electronic? What light switch are you using? Pilot lights making the ammeter swing 1/2 way down is not right. Let us know & someone will help.