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Discussion Starter · #1 ·
I'm having an electrical problem on my Majesty, and I want to describe it and bounce around a few ideas on it.

First of all, the bike and locale are not typical:
The bike is a 2000 model year Majesty 250 (YP-250) originally sold in the Japan market. It was gray-market imported to Thailand (where I live) before I bought it. (They don't sell maxi-scooters here, so if you want one you have to get it from another market.) I bought it three years ago, and have put almost 14,000 miles on it myself. Total mileage is now 55,000 miles/90,000 km. I can get parts and full service from the dealer I bought from in Bangkok, but that is about 250 miles from me. And usually he has to order parts from Japan. So visits to him with the scooter are rare. I can get lighter service done locally from a dealer by bringing in my parts and service manuals. Though there is a language barrier, these guys are pretty good on mechanical stuff. Not so sure about electrical though, and they can't order parts for me. I definitely have to be proactive about service issues owning a bike like this here! But it's a good and practical bike for in town, on the road, and carrying a considerable load of goods from the market.

The problem is that my battery started going down when I'm out riding. Lights go dim, and if I shut off the engine, I can't restart cause the battery is too weak. Also had the speedometer and odometer cutting out in a severe circumstance. Not having a kick starter, I'm stranded if it goes down too far. The bike seems to be okay when it is parked however; no drain-down occurring there.

I noticed a few interesting characteristics when the battery goes down while I'm out and about:

  • • When the battery is going down and the engine is still running, the lights do not brighten up at all if I rev the engine;
    • I do have a voltage rise at the battery when I run the engine: ≈14 Volts running, and 12.x volts with engine off (in a normal condition.) After the battery has drained down, before recharging I have 11.x volts on the battery.
    • I have a Garmin GPS with a power plug switched with the ignition. It turns on the Garmin when I turn on the ignition switch (indicating power present), but the battery on the Garmin is not charging up. It is draining down too.

I was uncertain about the condition of the battery, and felt it was close enough to replacement to give that a try first. I popped a new replacement in, but no change.

Having the voltage rise at the battery when the engine is running tells me I have generator action. Whatever the problem is, I'm guessing that the voltage rise amounts to nothing under load, and all the normal systems are just draining down the battery over time.

My next guess is the rectifier/regulator. I guess it could also maybe be the generator, but I think that less likely. Anybody agree or disagree? Or have any other ideas?
 

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Discussion Starter · #2 ·
Let me add also about the rectifier/regulator: It has one plug going into it with five wires; according to the schematic three white wires coming from the generator, one black wire going to a frame ground, and a red wire going to power other systems on the bike, starting with the starter and battery area. I'm wondering about taking some readings on the red and black wires, but not sure:

  • 1) What I should be getting other than ≈14 Vdc;
    2) That I could really effectively check much since it seems I already have that with no load, and I seem to be having a problem with it handling a load;
    3) Having the battery in the system might obscure the readings anyway. And as someone commented on another thread, starting the engine then disconnecting the battery is a good way to blow the rectifier/regulator.

I have a .pdf schematic, but not sure about forum rules on posting/sending?
 
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