V50 Charging problem

Technical Small Block V Twins (not new V7s)
1

Hi all,
I have a V50 with a charging problem that somebody may be able to help with.When running the charge light doesn’t go out until around 3000rpm.In fact it doesn’t fully go out because it’s still glowing slightly.At this point its showing 14 volts at the battery.I’ve changed the regulator and the rectifier but it makes no difference.I’ve been through the wiring and all seems to be ok there aswell.I’m wondering if it has anything to do with the charge warning light but any suggestions will be gratefully recieved.
Many thanks
Mark

2

Have you done anything before this started as that is usually a good place to start. 14V at the battery sounds pretty good, so maybe the problem is in the warning light circuit rather than the charging system itself.
There are a few helpfull guides on the Gutsibits website
http://www.gutsibits.co.uk/pr/TheShed/techdocs.php
or have a read of this one
http://www.thisoldtractor.com/guzzitech.dk/pdf/charging-around-the-circuit-john-noble.pdf

3

When I bought the bike the charge warning light didn’t go out at all.Also the Battery wouldn’t hold its charge.I replaced the battery,Tried a new regulator then changed the rectifier for one that I had that I knew was OK.This seemed to allow the light to go out but at a higher RPM than it should.I have since tried another rectifier and this has made no further improvement.

4

have you got the correct wattage lamp in the charge warning unit ?
usually a small amount of current is allowed to leak through the filament to excite the alternator ( they wont generate current otherwise)
if you have fitted the wrong wattage or an LED that could be the problem

5

Not to sure about this.After reading the article on the this old tractor link fron Don-Spada I’m starting to think this might well be the problem.I just presumed that because it was in there it was the right one.I think I’m going to change it and see what that does.

6

Try swapping it for one from another of the warning lights, see what happens then.

7

“Dark or twinkling charge warning lamp” usually means alternator brushes need checking / cleaning / replacing

8

That could well be the problem as the charging light relates to the current creating the magnetism in the rotor

9

Thanks,I’ll see if that works.I checked the Brush length before and they were ok but I’ll try cleaning everything.It didnt seem particularly dirty but you never know.

10

I had exactly this happen on my R80, reason was one brush stuck in its holder so not pressing on the slip ring properly, constant sideways pressure of the slip ring rotating had caused the holder to wear a notch in the side of the brush so it was hooked up on it. The actual length was OK so you never know!

11

You need 120ohm resistor in the warning light circuit to energise the alternator. If you do the maths it equals a 1.2W bulb. I had a similar problem with my V50 that I traced to the large connection block under the tank. It wasn’t the connector but the large red wire was loose in the crimp. Hope this helps.
Steve