Electrical issues are sometimes difficult to track down.

cape

cape

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Finland
I thought I would share some of my recent experiences with Laverda charging, regulator rectifier and voltage.

Background: Years ago, I started using Lithium battery. At that point I also modified some wiring. This is ancient history to you all, but to reiterate. What Laverda factory designed, was that the generator 3rd phase went from generator to light switch and from there to regulator. When the headlight is on, the two wires marked as VR and VB are connected, and so is the the3rd phase. When the headlight is off, there is no connection and 3rd phase is not in use. The reason for this kind of wiring is probably to prevent over-charging issues, and as such, it is basically OK. But there are couple of issues. First one is that the wiring is unnecessarily long. The second issue is that if the connectors get worn, there is a risk of 3rd phase shorting to handlebar. That wouldn't be good. Thirdly, if the light switch is turned on and off repeatedly, it will always generate voltage spikes, which are potentially harmful to both regulator and generator. Anyway, Laverda must have calculated that the system will hold, regardless. That may be the case, at least with lead acid battery and traditional shunt regulator. So, I modified the wiring, removing the VR/VB connection and run the wiring through a relay (which was activated by the light switch) directly to the regulator. This fixed the risk of phase shorting to handlebar issue. The wiring was also shorter. Otherwise, wiring is basically the same as original. And it worked with shunt regulator without issues.

Couple of years ago I swapped to a Shindengen FH020AA Mosfet regulator. Mosfet is a great regulator, it keeps the voltage steady at 14,3V or so. But then came the trouble. The voltage started to be unstable, and I thought that Mosfet must have components that are prone to voltage spikes and for that, it failed to operate. I bought a new one and to prevent it from failing, I removed the relay from generator 3rd phase wiring. Same result! Now I was confused, what was going on? I checked every wire, connectors, generator coils, measured everything with multimeter, basically everything I could think of. I swapped back to lead acid battery, no help. I calculated the electricity consumption (I have LED lights), and it turned out that the wattage with stock bulbs is around 96W and with LEDs around 33W. The difference is quite significant. This must be it! I added daytime running lights to the same circuit to get closer to the original consumption. No help! Whaaaaat? And the last thing I checked was the regulator ground connection. I’ve always grounded only to the bike’s frame, but it must have been insufficient. Now I have the regulator ground wire attached to the battery main switch and from there to the battery negative terminal. All good, steady voltage again. So, a simple fault that was a PITA to find...

-Sami
 
Ok, a shorted stator output wire to frame will not cause any duress on the stator winding itself. Standard shunt RR dead short the stator windings for regulation. A shorted turn on the stator itself is a very different matter. The bullet connectors oem stator to RR will be under rated for the shunt current, not the charge current however, ie black overheated insulation colour on the connectors involved with the now superfluous 3rd phase switch out of oem, which by the way puts the stator in an open circuit high voltage punch through on the insulation windings for that stator phase, let alone the effect on Star or Delta configuration, ie the phases are interlinked.

The oem Denso RR ( thats not Nippon Denso BTW ) was undersized and would fail in the shunt reg control function, ie the internal scr's were not rated for full 240W ( VA would have more meaning ) continuous shunt function of a fully charged battery.

Battery negative to starter motor frame direct 100A welding cable, been covered many decades ago, not least by myself. RR return connection to battery negative, usual under battery support bracket underneath "earth" connection corroded away from flooded cell battery days. RR regulation sense wire has to see actual system voltage, not a variable impedence path through old fuses, switches and wiring issues.

Sami, you may have a sense input wire issue remaining, as you distrurb the wiring in your recent actions, this sense wire for correct RR regulation has been noted prior, as you suspect. HTH j
 
Oh man, I'm really struggling to understand what iis_iis wrote. I have always thought that english is a relatively easy language to read and understand, but now I'm lost. Or maybe it's just too technical for me. Never mind, the wiring on my Jota is working properly.
 
Sami, some of your assumptions are not what happens in the case of the Laverda RGS factory wiring scheme, and substitute RR, not my intent to confuse, though it does happen. May well be it is all working properly on your RGS, poor earth connections are well known on this model. In particular the isolated motor mounting, the ill conceived short high current "earth" lead from battery negative terminal the the rear of the cast aluminium crankcase upper. Replace that short lead with a properly crimped welding cable, extended to the actual steel mounting bolt securing the starter motor. Aluminium unless properly prepared and terminated is a poor conductor for the 100's of amps that flow battery to starter motor. Frame is not a conductor or merit, mechanics perception or otherwise.

Intimating to you, that there may well be two or more issues on the stator/RR and the vital sense wire for correct RR regulation to occur. Most notable is sense wire problem equals high battery charge volts, low battery charge volts a stator to RR issue as a broad guide. Not sure that helps. More the matter of while your RGS may be rectified, what are you going to do if the incorrect charging voltage issue returns, likely or no. Philosophy is also a tool for fault identification, not just what is in front of you.

May like to review Robs Motodd charging system issues and multiple failures to rectify, as a posting here some time back, should you have any re-occurance of charging problems. We all learn as we go, first principles can avoid wasting a lot of energy or pushing a bike home, a wry smile here. Your confuscious friend... j. * can stay out of this of course, wont be offended.
 
And to prevent further confusion, here's the original wiring schema.
 

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And some electrical problems are easy to track down.....
Removed from a ‘dead’ 650 Formula.
 

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I fully agree that electric issues are sometimes difficult to track down.

The other day I started my Jota, which started immediately as always. Unfortunately, I stalled it when starting and then the starter didn't do anything.
I measured the voltage between the positive terminal of the battery and the frame and it was 12.5 volts (The voltmeter has a high resistance - practically no current flows). When I pressed the starter button the voltage collapsed completely. That looked like a defective battery - even though the gel battery was only 2 years old and was regularly maintained with charge maintenance in the winter!
So I turned off the machine again and connected it to the charge retention device using the buckle connection cable. And after a short time this showed that the battery was healthy (As shown in the circuit diagram, the positive and negative poles of the battery were directly connected to the connector charger cable) !
Then I connected a charger to the (built-in) battery via the positive pole on the battery and the frame. But the charger didn't show any current flow! Finally I removed the battery and discovered the badly corroded ground strap. And that explains all the observed effects - and with a new ground strap and a charged battery, the Jota runs perfectly again. - I tried to explain the whole thing in a simple circuit diagram - maybe it will help someone.Laverda Jota Starter process.jpg
 
Yes, an illustration showing that electrical components need a circuit, not just a one way delivery. Often overlooked, similar size cable/path return to the battery. Headlights are a classic example, relying on the "earth" return to the battery to go via the headset bearings.
I have seen poor motor earthing causing throttle cable melting (on a car) and tacho cable melting (on an SF) when the starter was tried.
 
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