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 - http://www.electrosport.com/electrosport_fault_finding.html

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.

 

Sounds like the alternator has failed on one phase.

 

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

 

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.

 

With the RR disconnected, the voltage between any two phases might be in
the order of 55V AC with the engine at 5000rpm. Check all 3 phases in
turn, they should all be the same. Another thing to check is the static
resistance readings on each winding and check from the windings to
earth. There should be no short to earth.

I've had one where everything was fine on the meter - no shorts, no open
circuits, but the fucker was fucking fucked. A new one cured it.

You really need a set of figures from the BoL or W/shop manual.

 

I have a BoL. I shall have a look.

 

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?

 

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?

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

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?

 

What does the BoL say the raw output should be? Assuming for the moment
the voltages you found are correct, I would say the RegRec is fucked.

 

agreed

 

Cars have an RR built into the alternator some way don't they?

 

Think so. I remember replacing alternator 'diode packs' in my yoof,
which I'd guess is the reg/rec equivalent.

--
Krusty.

http://www.muddystuff.co.uk
http://www.muddystuff.us
Off-road classifieds

'02 MV Senna '03 Tiger (FOYRNB) '96 Tiger '79 Fantic 250

 

gazzafield (_I.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.

 

This system on bikes came in roughly 1979 or so.
when I was selling this stuff we sold about 4 reg-rectifiers for every one
alternator stator (the bit with lots of windings) They were pathetically
unreliable, but did improve with time.

Some people did build their own, but whether it was worth it or not is
debateable.

mrcheerful

 

My bike - and the model - has a history of blowing RR's. When I got it two
years ago it popped one in a couple of months so I bought a new one. It
popped in a couple of months as well. So I bought a "High Power" one. It's
lasted two years.

 

<snip>

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.