xpa 750 overvoltage

[farfons]

Hi, i'm new in the forum, sorry if it isn't a v11 related problem but i hope you can help me. I'm experiencing a very strange problem, from the regulator of my 1997 guzzi xpa 750 (ducati energia) i've a voltage from 13 to 17v accordingly to rpm increase, two batteries are gone and changing the regulator didn't change the situation. From the stator i've circa 90/100v ac at "max" rpm. i've read about this issue appened to other owners, have you experienced something similar? i've read several interventions about this kind of issues from @Kiwi_Roy user here. ì've attached a video to better explain. Thanks and sorry for my english.

Filippo

https://sendvid.com/z7jdcd3b

[Pressureangle]

The regulator has to sense a voltage differential to know what to do. A possible failure here could be that the regulator is not sensing ground. Use a jumper wire to provide a secure ground to the regulator body, or if it has a ground wire, then between the ground wire and battery negative to see if it makes a difference.

[farfons]

i've used a 2.5sqmm wire to ground the the regulator body and i've tried also to connect directly to battery negative with no result. i'm afraid that the problem is in the "positive side" of the voltage reference but don't now how to change the actual configuration to a new reference point to test. Thanks for your answer!!

[Pressureangle]

28 minutes ago, farfons said:

i've used a 2.5sqmm wire to ground the the regulator body and i've tried also to connect directly to battery negative with no result. i'm afraid that the problem is in the "positive side" of the voltage reference but don't now how to change the actual configuration to a new reference point to test. Thanks for your answer!!

That's the harder part. If the reference channel of the regulator (I think all modern regulators sense through the charge wire) has any poor connections, the voltage sensed will be low, causing the regulator to up the voltage output. So next I'd find the first connection from the regulator sense or charge wire, and jumper that directly to battery + to see if that corrects the output. Beware that if you have weak connections in the charge circuit, you could have significant current in your jumper wire, overheating it. 

[farfons]

if you mean directly from the regulator i've tried to connect the wire (black wire from ducati energia regulator in a 2 pin connector, the other one is for the battery bulb) directly to the battery positive with no success. or you mean an other operation? 

[Pressureangle]

I'm not familiar with the particular layout of this regulator. You have 2 input wires from the alternator, yes? Or 3? Then you have a Battery + going out to charge, and a no-charge lamp wire? You might try grounding the bulb wire to see if that's the ground reference. 

[farfons]

14 hours ago, Pressureangle said:

I'm not familiar with the particular layout of this regulator. You have 2 input wires from the alternator, yes? Or 3? Then you have a Battery + going out to charge, and a no-charge lamp wire? You might try grounding the bulb wire to see if that's the ground reference. 

the layout is 

 

-2 yellow wires from regulator

-1 red wire +12v to battery

-2 wires > 1 black voltage on key 1 white to no charge lamp

 

i've attached the schematic of the regulator provided by @kiwi_roy in this forum and an image of the regulator itself

 

[Pressureangle]

Ok. The answer lies in notes 1 and 5. 

The wht/blk connector mate on the frame harness is suspect. You'll have to do some patient sciencing here. 
Pull the plug very slightly apart so you can measure the actual voltage in from the headlamp circuit. That should measure within .2 volts of battery. If it measures a difference of more than .5 volts, you have a meaningful connection fault. If you measure a high differential, measure at the next accessible point upstream; if the mating connector in the harness is not molded as the regulator side is, probe the wire where it meets the terminal to see if you have a bad crimp. I hate poking holes in wires, but if you have to to measure voltage in the harness before and after the plugs it's necessary. I'd start by chasing the accessible points first. I don't think it will take very long to isolate the problem point.

Another point of order is to use your meter to measure differential between the regulator case and battery negative. Though you've run a bypass, it's still important to know the ground is sufficient not to have a differential. 

[farfons]

42 minutes ago, Pressureangle said:

Ok. The answer lies in notes 1 and 5. 

The wht/blk connector mate on the frame harness is suspect. You'll have to do some patient sciencing here. 
Pull the plug very slightly apart so you can measure the actual voltage in from the headlamp circuit. That should measure within .2 volts of battery. If it measures a difference of more than .5 volts, you have a meaningful connection fault. If you measure a high differential, measure at the next accessible point upstream; if the mating connector in the harness is not molded as the regulator side is, probe the wire where it meets the terminal to see if you have a bad crimp. I hate poking holes in wires, but if you have to to measure voltage in the harness before and after the plugs it's necessary. I'd start by chasing the accessible points first. I don't think it will take very long to isolate the problem point.

Another point of order is to use your meter to measure differential between the regulator case and battery negative. Though you've run a bypass, it's still important to know the ground is sufficient not to have a differential. 

I'll do all the tests you suggested. thanks a lot for your help!!

[Pressureangle]

An interesting point to the thread observer; the regulator in question appears to be identical to the one on my '97 Sport-i. Though my battery has always charged, I had suspicions about my system so installed a LED volt display which showed output to be a little weak. Improving grounds brought me to 13.8 volts, which I thought a bit low but I see in the schematic this is the setpoint intended. At this past Spine Raid, and just before, I noticed that the voltage increased to 14.2 and I was pleased but confused; now I have to inspect my reference circuit to see if it's actually overvolting marginally as is the OP's bike here.

[Weegie]

I was going to add earlier to check the Voltage on the black wire which I believe is the reference but didn't as @farfons stated he ran that wire to the battery and there was no change, the same with the earth but again he did that as well.

In my experience on my Sporti that double "jack" plug comes apart easily, for now they're held together with a cable tie, but I'm going to cut them both off and replace it with something more secure.

The reference itself is measured in a crap place passing through a fuse and 2 relays (starter & headlamp) in the Sport, not to mention the wire running the length of the bike, so corroded or dirty contacts could cause the reference to "see" low volts and lead to overcharging.

That said you've already eliminated these as potential problem by running wiring to the battery to test and found no difference, so you've reached my level of ignorance on the issue.