Strange Charging problem.

Well, strange to me. This has been deliberately posted to UKRCM for any auto sparks to muse over.My bike was not charging its battery especially when running with the lights on. So I checked out the excellent flowchart here -

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My bike was failing on the first test basically when checking the voltage between the red RR lead and the positive terminal of the battery. [1] I was getting a reading of between 0.45 and 0.65 volts. So I duly ripped open the tape on the loom and tore out the red wire from my battery to the RR and ignition block connector.

I got new connectors and the wire was slightly thicker than what I had removed. I also replaced the connector at the fuse with an in-line fuse holder. I connected everything up and checked the readings. A charging rate of 13.6 to 13.8v. Not that great but acceptable. Reading between RR red wire and battery positive - 0.4v. Bollocks. I continued to run the bike for about five to ten minutes as I basically farted around and wiggled and poked things and decided to check on the readings.

The reading between the RR red wire and battery positive had gone into minus volts and the charging rate had disappeared up its own arse and was around

11.8v. The RR was also bloody hot after such a short time. Light was fading and I was pissed off, so I covered the bike.

Tonight, fully refreshed, I checked all the wiring I had replaced in the loom. Everything looking OK. Start up bike. Charging rate of 14.2v to

14.5v. Result! I let the bike continue to idle for around five to ten minutes again and checked the charge rate. 12.7v and visibly falling as I held the meter on the battery. Shit! The RR was also rather hot.

So, my question is. What's gone wrong? I have my own theory but I would like to hear suggestions as to what the hell has happened.

[1] A week or two before this it had flattened the battery and it had failed on the next test but as this was simply cleaning up the earth connections it was quickly cured.
Reply to
gazzafield
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"gazzafield" wrote in message news: snipped-for-privacy@pipex.net...

Sounds like the alternator has failed on one phase.

Reply to
mrcheerful

I take it this will come to light if I do the check to check the alternators voltage output?

Reply to
gazzafield

should do, there are usually three alternator output wires (three phase) you should get equal readings across any pair, usually there is one shorted to earth.

Reply to
mrcheerful

I have checked the alternator output and I was getting 67~72v at around

4,500rpm from all three pairs. All well and good thought I until the wife said "put your lights on and try it". Lights on charging rate dropped to 11.8v. This indicates to me that the alternator is indeed at fault when under load as I had a car that had the very same symptoms and only got me home down a dark country with no lights at nearly midnight! That was, erm, interesting. Do I presume correctly as every other indication says that all sytems are fine?
Reply to
gazzafield

On Thu, 13 Jul 2006 22:05:13 +0100, gazzafield wrote in :

Sounds suspiciously like a bad connection somewhere -- disappearing voltages with load almost always indicate unwanted resistance.

How come SWMBO knows more about electrickery than you?

Reply to
Dr Ivan D. Reid

Have you checked for voltage drop on both positive and negative circuits while under full load? (Don't assume because the alternator is firmly bolted to something that it's making a good electrical ground)

Checked the slip rings and brushes? Checked all the diodes?

Reply to
Dave Plowman (News)

gazzafield (rufty_tufty snipped-for-privacy@nospam.saysI.ko) gurgled happily, sounding much like they were saying :

Yep.

Older stuff might have a separate regulator, but the rectifiers are still within the alternator.

Reply to
Adrian

In message , gazzafield writes

Try another RR - this is very similar to the problem with my gpz. I too spent ages on that bloody red wire, and then gave up and tried another RR - which cured it.

Reply to
mike. buckley

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