Charging system warning light

[sp838]

My charging system warning light is not turning off after I start the bike. Went out for a ride yeaterday, it flickered and then turned itself off after I pulled away so I thought, "a little weird but probably ok", but then after I got up to speed it came back on and stayed on solid, so after a few miles of watching it and hoping to see it turn back off, I decided to turn around, hurried home, and put a voltmeter on the battery expecting to see it show that it was being drained. Battery read 14.17V.

 

Bike performed normally otherwise, idled fine, lights worked etc. I checked the wires for the r/r, all looked good. Ground wire is happy, yellow wires to the alternator are good, red wire out to battery seems fine, blue wire which sends the warning to the dash is clearly ok too. Did not look into the alternator yet. Did not check with voltmeter while running at idle yet.

 

Any ideas as to what might be going on / where to look around first?

 

Thanks!

[Guzzi2Go]

Going by the lamp alone, one can only say that the tension on the battery is higher than the tension produced by the charger. Could be a glitch, but could be a sign of a malfunctioning regulator.

 

If you have a voltmeter, I'd measure the battery before starting the engine (should drop to 12.6-13V within few hours after ride), then start the engine and measure again. See if the tension goes up and the lamp goes off.

 

If the lamp goes off, rev the engine high and see if the tension goes above 14.6V (upper limit according to the manual). If yes, check the 30A fuse and possibly start looking for a new regulator.

[bbolesaz]

Be careful about drawing conclusions from battery voltage readings. Particularly if you don't have a load on the battery at the time.  Batteries tend to have a "knee" shaped discharge curve.

 

 

So, a battery will tend to show something close to rated output until it is near death.

 

You probably are not charging.

[sp838]

Thanks guys. I'll take those measurements, and will also do the diode test on the r/r tonight, as well as check voltage at idle. 

[sp838]

So, little update, I first tested parasitic loss at the – terminal, only 1mA which is what I was hoping to see. My speedo draws that to store mileage and GPS location. I then tested to see if the bike was charging, and it appears to be: 14.4V at idle, then as I went up the rev range, it dropped down to around 12V at 2K, then back up to 13V at 3K, and around 14.5V at 5K RPM.

 

So it's charging. All the while, the idiot light on the dash was solidly on. No flickering, no turning off then back on again. I'll do the diode test this evening, thinking I might also do an AC test on the stator. I might also wire up a temporary idiot light to the r/r just to see if it's the idiot light wiring in the harness that is to blame. Hoping that's it.

[swooshdave]

14.4V at idle sounds high, what is your idle speed?

 

I think it sounds like a regulator issue...

[luhbo]

Yes, don't fry your expensive Hawker. Maybe the red light indicates just a faulty regulator. Then it's not necessarily a non charging issue as it was with the older Bosch alternators up to the LMIII or so.

[sp838]

Rectifier passes the diode test. Thinking it's the reg. as well. Unfortunately there's no way to really "test" that.

 

Idle speed is 1k. I've always had around 14.5 at idle, even back when the bike was bone stock...

[Guzzi2Go]

According to the manual, the alternator gives you 15V@1000 RPM and the regulator is capable of giving you 9,5A DC there. So I'd say this is not so unusual. What I find unusual is that the battery is so high after you switch the bike off. However, all the numbers you mentioned are within limits.... 

 

Your battery charges high and this is not apparent to the regulator. The regulator will compare the voltage on the black wire (paired with the white for the lamp) against the output on the red wires. Bad black wire connectivity may contribute to "negative perception" of the battery tension. Perhaps to measure resistance between the battery(+) terminal and the regulator's black wire terminal? The current flows through the ignition switch here, so a loss there may explain tension measured lower than actual.

 

P.S.

 

Actually, according to the schema, the connection runs through the headlight relay, not the ignition switch. Guess the manual is not consistent or precise enough there. That would be red-black wire from the headlight relay.

 

P.P.S.

Thinking a bit more about it, that does not make sense. The lamp should go on if the black wire is higher than the red wires. No voltage drop between the battery and the regulator can contribute to that.

[Kiwi_Roy]

The regulators I have dissected are set at 13.8 Volts, the bike picks up another ~0.5 through drop in the headlight relay, more if it's an earlier one because the headlight relay was fed through the start relay.

Something to try is unplug the male/female connector and turn it so only the black regulator wire is connected, if the warning light still comes On it's a short to chassis in its wiring.

IMHO the light is pretty useless as it will only work if the regulator is ok

 

 

Sent from my shoe phone!