Electrical troubleshooting help needed
 

All is not well with Northwind's bike... Not charging right, or possibly losing charge to earth. The battery seems healthy enough- it starts very strong after a charge, and it runs fine for as long as I leave it running. What I'm finding is that if I charge it overnight, start it and ride to work with headlights on, then it'll be completely stone cold dead when I come back to it- maybe one wheezy turnover at most, then clicks. Not just a bit flat, but almost completely flat.

If I ride to work without lights, then usually there's enough charge to restart.

Now, sounds like classic reg/rec, doesn't it? But I'm not not sure. 21Quest sent me a spare (which we don't know works, but have no reason to assume it doesn't) With either reg/rec, I get 13.6V or thereabouts across the battery with the engine running and lights on, at idle. But as the revs rise, the volts drop, and by 5000 rpm or thereabouts it's making mid 12s. Is that normal? I'm no electrician (I've had very few electrical problems so I've never learnt how to fix them ;) ) but it just strikes me instinctively as wrong.

Really not sure what's up here :( It's on to charge now, any other sensible things to try?

I thought the charge should go up with revs.If all is well you should see the lights get slighly brighter as you rev it.

As for fixing it, sorry not a clue. Not sure I could even wire a plug. :oops:

I had a similar problem and it turn out that my battery was goosed!!! Have you had your battery tested?

The voltage should definitely rise as the revs do.

I'd say swop the battery, especially if it's the same one since you've had the bike.

Nah, the battery's only a year or so old... But it charges fine from a charger, and holds a decent charge too. I doubt it's the problem really.

Hi Northwind. No electrician here either.

The Haynes manual states that with the lights on main beam you should be getting 13.5- 15 volts. It gives a way of checking, but suspect as it's not overcharging it could well be your alternator, or bad earths.

The battery before the one I have now only lasted 6 months and it was yussa one as well :cry: And you only get a 3 month warranty on batteries!

check your altenator output. Put your meter on the ac volt setting and meter out between the 3 pairs of yellow cables going to your R/R.

3 pairs yes, imagine each yellow wire as A,B,C you need to check A-B, B-C, A-C. expect to get somewhere between 70-90V on each pair when the engine is doing about 5000 rpm.

Right, had a dig in the service manual and found a load more tests that I didn't know about, I'll get cracking on those.