Guzzi wiring

[Guzzidad]

  I have an 01 EV. Two years ago it left me stranded on I-10 near Pensacola. Battery showed 12.5 volts but it didn't have any power. The Guzzi dealer in Pensacola got me right in, got me a new battery, and discovered the VR was over-charging. Had a new VR over-nighted and installed and they sent me on my way. Well, the new VR was over-charging same as the old one but at least I made it home. I put a lot of thought into this problem even though I continued to ride the bike knowing that over 4000 Rpms the VR was sending over 15 volts to the battery. Finally today I decided to try something. I went to the auto store and bought a $5 relay. I wired it so the headlight circuit energizes the relay and the power for the headlight comes direct from the battery through a fused circuit. I now have 13.8 volts to the battery at 4000Rpms and I'm hoping the headlight will be brighter at night. I'm pretty confident this is a permanent solution but time will tell.

[Chuck in Indiana]

Normally, the overcharging is because the VR is losing ground from that dinky little wire in the harness. A ground wire from the VR to an engine bolt should do it. Say 14 gauge with star washers.

[Guzzidad]

  Tried that. Didn't work. The headlight bulb caused a 2 volt drop in the circuit telling the VR to go into overtime.

[Wayne Orwig]

Sounds like you needed to improve the path to the VR sense line. Removing some load is one way to do it I guess. I would still wonder where the drop is in the line. You may have a bad connection somewhere that will start the issue all over again.

[Kiwi_Roy]

Typically the Voltage drop through the headlight relay is about 0-6 Volts so 13.8 + 0.6 ends up at ~ 14.4 Volts at the battery.
Your bike probably has a bit more Voltage drop in the relay sockets hence it overcharges.
Add a larger headlight bulb and the battery Voltage goes up
Add headlight relays direct from the battery and it goes down

I have been giving this issue a lot of thought, I think the regulator should get it's reference from the ECU relay, that has a constant load of only a few milliamps.
The Voltage regulator only pulls about 15 mA
It's very easy to boost the charging from 13.8 to 14+ Volts. it's just a matter of adding a resistor or diode in the reference circuit, send me a PM if you want details.

Make sure the regulator has a really good ground, the charging current flows back from the chassis to the alternator through the regulator to chassis contact
A short wire between the regulator case and an engine bolt is the best thing you can do

[Guzzidad]

   OMG, I already answered your question. The voltage drop was the headlight bulb. When I unplugged the bulb regulation was correct. The VR sense wire is through the headlight circuit. That's why I chose to use a relay. A relay coil causes nearly zero voltage drop. The headlight bulb caused a drop of 2 volts.

[Chuck in Indiana]

   OMG, I already answered your question. The voltage drop was the headlight bulb. When I unplugged the bulb regulation was correct. The VR sense wire is through the headlight circuit. That's why I chose to use a relay. A relay coil causes nearly zero voltage drop. The headlight bulb caused a drop of 2 volts.

I think OMGs post is asking "why" the headlight bulb is causing a drop of 2 volts.

[charlie b]

When I replaced the alternator, regulator and rectifier in my bike I had to change where the sensor line was connected.  The original location had too much voltage drop and it was causing an over charge condition (just by 1 volt).  I routed the sense line to 'free' lug on the fuse block and the problem went away.

[Kiwi_Roy]

I think OMGs post is asking "why" the headlight bulb is causing a drop of 2 volts.

Bad relay or relay base.

[Wayne Orwig]

   OMG, I already answered your question. The voltage drop was the headlight bulb. When I unplugged the bulb regulation was correct. The VR sense wire is through the headlight circuit. That's why I chose to use a relay. A relay coil causes nearly zero voltage drop. The headlight bulb caused a drop of 2 volts.

You missed my point. Something is weak in the original headlight/VR feed line. That weakness is still there, feeding the VR. Hopefully it isn't a future issue.

[Kiwi_Roy]

You missed my point. Something is weak in the original headlight/VR feed line. That weakness is still there, feeding the VR. Hopefully it isn't a future issue.

As I said, the Voltage get's lost in the headlight relay and socket
Update, it's even worse on some of these bikes because the headlight is fed through that dammed Ignition switch, we all know what happens in there
http://www.thisoldtractor.com/guzzi007/schematics/2000_Jackal.gif
See where the feed for fuse 3 & 4 comes from, the regulator senses Voltage after the headlight relay.
That wiring is just too stupid for words.

Lately I have been advocating hooking the regulator to the ECU relay, that has minimal load on it therefor little Voltage drop. This will result in lower battery Voltage without the benefit of the normal Voltage drop but it's easy to boost it up again, a simple way is just adding a diode to give it 0.6 or a resistor.
I have posted the regulator circuit here before.

When I replaced the alternator, regulator and rectifier in my bike I had to change where the sensor line was connected.  The original location had too much voltage drop and it was causing an over charge condition (just by 1 volt).  I routed the sense line to 'free' lug on the fuse block and the problem went away.

That's a very good fix IMHO

[Guzzidad]

   As Kiwi Roy said, the headlight circuit goes through the ignition switch as well as other switches and also provides power to the dash lights. What I know to be fact, when I unplugged the headlight, regulation was correct. Had 12 volts at the plug. But when I plugged in the headlight bulb the voltage dropped to 10 volts. I believe the wiring size is too small to handle the load as well as the distance it has to carry the load. I'm confident in my remedy. It's cheap and easy and electrically rational.

[Kiwi_Roy]

   As Kiwi Roy said, the headlight circuit goes through the ignition switch as well as other switches and also provides power to the dash lights. What I know to be fact, when I unplugged the headlight, regulation was correct. Had 12 volts at the plug. But when I plugged in the headlight bulb the voltage dropped to 10 volts. I believe the wiring size is too small to handle the load as well as the distance it has to carry the load. I'm confident in my remedy. It's cheap and easy and electrically rational.

Perfectly rational, your red suspenders are in the mail.

[Kiwi_Roy]

I had the opposite, a loss of charging although the lights were still working, as a temporary fix to get me home I ran a wire direct from the battery and wrapped the other end around the Voltage reference pin of the regulator. There's all sorts of things you can do in an emergency like grounding one yellow wire from the alternator that will force it to charge the battery through the rectifier in the regulator half wave style, may not be enough to run the lights though and you might need to keep the revs down.

[Guzzidad]

    There's all sorts of things you can do in an emergency like grounding one yellow wire from the alternator that will force it to charge the battery through the rectifier in the regulator half wave style, may not be enough to run the lights though and you might need to keep the revs down.


    Now THAT really confuses me Roy. You're suggesting running one line from a three phase AC circuit direct to a DC ground? Sounds dangerous to me. But thanks for the red suspenders. Finally, after 35 years of riding Guzzis, I have been awarded the most prodigious symbol recognized the world over as a Guzzi affectionato. 

[Kiwi_Roy]

The Guzzi alternator is single phase, each end of the coil is connected to a diode leading to the red wire output (this is only half of a rectifier bridge)

If you just focus on the wiring top center (diodes and Alternator) and ignore the rest you will see by
grounding one yellow wire it forces the other diode to pump current into the battery every second half cycle.

Note: I haven't actually tried this but I would before I walked home.

I was stuck on the road once with a failed regulator so I purchased a full wave bridge rectifier and limped home with the alternator hooked to rectifier and battery, I had to run at low revs, too many revs overcharged the battery and the ECU would shut down, I reckon 1/2 wave would be about right.

[jmac851]

I have a 96 Cal 1100 and a 98 EV and they both charge 14.9-15.1 at hwy speeds with Odyssey batteries.  If I squeeze in a Walmart tractor battery, it will go down to 14.1.  More battery to charge. 

[Guzzidad]

   
I have a 96 Cal 1100 and a 98 EV and they both charge 14.9-15.1 at hwy speeds with Odyssey batteries.  If I squeeze in a Walmart tractor battery, it will go down to 14.1.  More battery to charge.


      Interesting. Do you think it's really because the battery is just a bit larger or rather it's the difference between lead-acid batteries vs AGM batteries. Never crossed my mind that charging would be affected by what type of battery is in use.