Fried Rectifier

[raz]

If you took a 12 volt battery and placed that in series between the regulator and ground (with correct polarities of course, ground of the regulator to the +12V battery terminal and the - terminal of that battery to the real ground), you would now have a regulator that would think it's putting out 12 volts but with its case ground at +12 volts, it's output would really be +24V. This is pretty much what a class H audio amplifier does, so there isn't anything magical about the theory.

I appreciate your efforts Carl. You almost convinced me now... but no. I will stay with the battery example since it's easy to picture. Let's replace the alternator and regulator with a huge car battery. What we now have is just two batteries in parallel. The better battery will charge the worse one. Say the smaller battery is very weak and the bigger battery is very powerful. Now put a 10 ohm resistance on the negative wire. Would you say there would be more than 12 volts across the small battery now? I think not.

 

If the alternator was a 20V DC source with a common ground to the regulator and battery, you would be right. Like a bad grounding of a 7805 voltage regulator. But this is not like that, it's more like my example above.

 

Or am I wrong?

 

The rest of your reasoning is of course correct. I think noise and spikes is what kills the ECU. A bad grounding on a Guzzi is anything but a static resistance.

[Guest Gary Cheek]

I think Carl's point is that the regulator case ground is vital to good performance from the regulator. Regardless of regulator scheme. People tend to forget the FULL output from the regulator is a series regulator flows through BOTH the positive and negative , or CASE. Indeed it is importatnat. A better scenario, from a regulation standpoint would place the "regulator" (actually a rectifier/regulator) very close to the battery. Since the cooling is better up front and long AC runs from the alternator could wreak havoc with the PCM the regulator is where it is. Next best scenario would have LOW resistance,HEAVY GAUGE wiring from reg to bat. The factory of course skimps on copper so there is room to improve here as htere was with the lighting system. A 10 or 12 gauge wire from the case ground to the bat negative along with a nice fat 10 or 12 from regulator positive to bat will ensure ggod regulation and efficient transfer of energy to the storage battery.

 

With a SHUNT system a bad ground will cause excessive voltage, With a series regulator, depending on WHERE the ground is high resistance the output USUALLY goes LOW. If the ground is in a part of the circuit that senses system voltage however the system may go high trying to make up what it mistakes for a low voltage condition.

[dlaing]

I appreciate your efforts Carl. You almost convinced me now... but no. I will stay with the battery example since it's easy to picture. Let's replace the alternator and regulator with a huge car battery. What we now have is just two batteries in parallel. The better battery will charge the worse one. Say the smaller battery is very weak and the bigger battery is very powerful. Now put a 10 ohm resistance on the negative wire. Would you say there would be more than 12 volts across the small battery now? I think not.

 

If the alternator was a 20V DC source with a common ground to the regulator and battery, you would be right. Like a bad grounding of a 7805 voltage regulator. But this is not like that, it's more like my example above.

 

Or am I wrong?

 

The rest of your reasoning is of course correct. I think noise and spikes is what kills the ECU. A bad grounding on a Guzzi is anything but a static resistance.

Interesting analogy.

So I guess it boils down to whether the resistance to ground blocks more of the flow than the effect of the control signal.

I don't know the answer for sure, but I suspect the control signal has a greater effect.

We should also keep in mind that the control signal and charge also flow through the positive side, so theoretically a bad connection there can do as much damage as a bad ground...YMMV, as some bikes are prone to bad grounds and some to other bad connections.

I believe the Ducati regulator on our bike gets its positive reference from the problematic lighting wiring, so a problem there can manifest itself in the charging system

When my regulator went, I also lost a path of little resistance between regulator and positive terminal of battery, so the problem could also be that wire and not the ground.

I did not notice any high voltage, just low voltage.

The Electrex regulator rectifier that I replaced it with, gets its reference from between battery and ground as opposed to between lighting wiring and ground. I think that is a more reliable design.

[wambiker]

Hi all, I fitted an electrex world unit yesterday, I think this is similar to the American units mentioned in previous postings, now seems to be charging fine. Has the same five wires 2xyellow,1 black, 1 red and 1 white. Connected up yellows, black to earth, red to red/green,white to blue. I left the red/black original alone. Everything works, charges to 13.9 volts and fitted ok. Still think my oddesy battery is fried but I'll give it a couple of weeks and see if it recovers. Electrex world is a UK company so might be off use to UK and European members, they dont actually list V11s, but list 1100 sports and calis it was an RR451 unit, ordered Thursday, here Friday good service.

Cheers Gary

[Guest Gary Cheek]

Adding headlight relays actually improves regulatior function. A high resistance in the sense circuit will cause an erroneous low voltage signal. The regulator will kick up the output and actually cause a higher voltage than desired at the battery.The headlight drain causes a voltage depression at the point where the regulator reads what it takes as battery voltage. By running the headlights on their own feed the voltage at the sense point is closer to the actual battery voltage. In the Guzzi/Ducati system the positve sense input is critical to proper regulator action. While a high resistance regulator ground is most likely to cause low output, a voltage drop at the positive sense lead will more likely create an over-voltage condition.

[raz]

Adding headlight relays actually improves regulation. A high resistance in the sense circuit will cause an erroneous low voltage signal. The regulator will kick up the output and actually cause a higher voltage than desired at the battery. In the Guzzi/Ducati system the positve sense input is critical to proper regulator action. While a high resistance regulator ground is most likely to cause low output, a voltage drop at the positive sense lead will more likely create an over-voltage condition.

That's good news since I ordered 6 GEI relays instead of the 4 that needed replacement. The six of them cost 1/25:th of a CF hugger (as if I didn't buy that too ). It seems to me one of the Best Things[tm] you could do to treat your pre-Norge Guzzi is relay your headlight. Together with Philips Night Vision bla bla bulbs I expect the light to be an order of magnitude better.

[Guest Corse]

Good thread. My newly acquired but used 2000 V11 just shut down with a flat battery. Not had a chance to check the rectifier but battery seems to be charging up ok on battery charger. What alternatives exist in the US to replace the recitifier?

[Guest Gary Cheek]

http://www.euromotoelectrics.com/EDLMG.html

 

These folks have all you will likely need.

[rossoandy]

Along the lines of this thread...

I noticed tonight that my V11 charge lamp is taking longer than usual to extinguish..ie its on at idle ad dimming by 1300rpm but not out until say 2000rpm,and by out I mean not glowing just a little.

Hmmm....bad earth?..........thinking aloud here Ive also noticed a little pause sometimes when the starter buton is thumbed.....sounds like an earth to me?

yet another job..

[raz]

Along the lines of this thread...

I noticed tonight that my V11 charge lamp is taking longer than usual to extinguish..ie its on at idle ad dimming by 1300rpm but not out until say 2000rpm,and by out I mean not glowing just a little.

Hmmm....bad earth?..........thinking aloud here Ive also noticed a little pause sometimes when the starter buton is thumbed.....sounds like an earth to me?

yet another job..

I've been told the V11 has the rectifier bolted to frame so it should have good grounding. Maybe there's some bad connection at the battery side. I guess you should check the positive junction at the starter too. Also, you may want to check voltage at battery before starting, and during idle when lamp glows as well as when lamps out completely. Maybe it could be sympthoms of a bad (as in end-of-life) battery, I'm not sure.

[rossoandy]

I've been told the V11 has the rectifier bolted to frame so it should have good grounding. Maybe there's some bad connection at the battery side. I guess you should check the positive junction at the starter too. Also, you may want to check voltage at battery before starting, and during idle when lamp glows as well as when lamps out completely. Maybe it could be sympthoms of a bad (as in end-of-life) battery, I'm not sure.

Thanks raz...doubtful ts the batery though as its got a hawker battery thats not two yrs old yet...I will check all conns tmrw.