Battery charging only when lights on?
 

Bike 3AJ 1988 XT Tenere

I have a small earth leakage somewhere on the bike that drains the battery if left for a month or so. It's only 0.05Amp or 28.8KOhms, take your pick but annoying as hell. I think I'll just but a breaker switch in line of the ignition terminal. However I have always noticed that when riding by battery seems to go flat(ter) of it's own accord anyway. I ride with the park lights on thinking that the battery will charge quicker. Turns out during these tests that the battery only receives charge when the main lights are on.

Is this normal?

No, the alternator should charge all the time the engine is running.

Well, mine does, anyway :)

My alternator / stator whatever does work though. Lights etc work fine if I disconnect the battery with the motor running.

The loom is a simple affair and you cant really cock it's connectors up. So what gives? Any ideas guys? I also think something must be amiss.

May not be applicable???? but - My TTR600RE has a relay & diode set-up for the lighting system. The lights are (were) always switched on, but only lit up when the bike was actually running. How it works is there is a diode in line with the light relay. The bike must be running - power needs to flow from the alternator to power the diode & work the relay that switches the lights on!
Now this may be nowt to do with your problem, but thought I'd mention it in case there is something similar in your bikes wiring system?

Thanks for your input Pigford but the XT is different. The lighting system is a secondary circuit and in the wiring diagram appears to bypass the voltage regulator.
I am beginning to suspect that the voltage regulator has blown. What bothers me tho and is a torpedo to this hypothesis is the lighting system is getting a clean 12.5V.

Ever just want to sit down and give up? This electric problem is giving me the right heebie jeebies

On some old Brit bikes, one set of alternator coils only were used when running without lights. The other two sets were only switched into the charging circuit when the headlight was turned on. Maybe your bike is not charging through the first set of coils?? maybe faulty switch or broken connection somewhere.

Mate.. are you sure you ain't got a dead regulator/rectifier?!

Fully charged battery..ride some 10-20 miles....goes completely flat and won't turn the engine when trying to re-start it? :confused1:


Vando

Im going to put my money on poor connection between the reg/rec and the battery. In my case the reg would throttle voltage before voltage at the battery was high enough, this was because of resistance causing voltage drop in the charging circuit. Ie the reg detected a higher voltage than eventually reached the battery. To test connect positive of reg to positive battery with dc20 voltmeter while bikes running repeat with negative terminals- should be a tiny voltage- below 0.2v when idle and nt much higher when reved.

Thanks Gawain. You are quite right when it's coming through when the lights are on. I will rewire the reg to battery connections and see. I have to get a better voltmeter. I have sourced what the correct resistance to the coils should be. If they are within tolerance then regulator issues it is.

Thanks guys for your input. Twirling spanners for me is easy enough. Electrics.....that's wizardry and witchcraft and general dabbling of the dark arts.