28 Amp Problem...

DaveM

DaveM

Joined
Jan 27, 2009
Messages
1,276
Location
Wilton, NH
Bike
2021 BMW 1250GS
Well, this afternoon was done work early and went on a 200 mile trip along some twisties... That was the fun part!!

I noticed last weekend, my voltmeter dropped down to 12.6v while on the highway for about the last half hour of my trip last weekend. Today when I left again it was at 12.6v and on the highway went up to 13.0v for a little bit but then dropped down again after about a half hour. When I put on my driving lights it would drop to 12.1v down to 11.9v. Normal on the highway and also at speed voltmeter would be at 15.0v - 15.1v. On my way home today it just kept slowly dropping, the good thing is that I made it back home and when I pulled into driveway voltmeter dropped to 10.2, shut the bike off and bike would not start. Also headlights were very very dim. I put bike in garage and hook up battery charger, after about two hours. I checked bike and the battery at just about at 12 volts found the rectifier had somewhat melted, connector for rectifier is just about melted, can not even take connector off. The main red 30 amp connector is also a little melted. I started bike and at idle was putting out 11.6v and at 5000rpm was putting out 12.7v. ......

OK the big question is ....Is it time for the 40Amp upgrade??

Do you think it could be something else?

Thanks!!! Again, the good thing is I made it home and am not stuck out on the road!
 
That's what it sounds like. I'm sure someone can chime in with more technical detail of what happens when the alternator fails.

But I am sure a 40a upgrade will cure your ails!
 
how many miles have you done please
I have 200k km or 125kmiles with no problems
Paul
 
It shows all the signs. I would upgrade. I haven't experienced the problem yet, but am planning to install a 40amp altenator. Hopefully before the current one fails.
 
The problem may be localized to the rectifier. The damaged/corroded/melted connectors are a sure sign that something needs attention!

You may be able to replace the rectifier and repair the connectors. Many times owners have removed the connectors and soldered the wires in place.

It really depends on how much money you want to spend......

You may be able to get a rectifier from someone that has done the 40amp upgrade (rect built into alt) so it's worth asking for. I've already "donated" my rectifier to another rider.

But keep in mind that the problem may have progressed to the alternator. I had a winding go open on my 28 amp so it required replacement.

Good Luck, which ever way you go!!
 
Thanks for all your input.....I think it is time to upgrade!! I don't think I am going to mess around with the rectifier or doing all sorts of tests. I take this as a sign to just bite the bullet and do the upgrade, I actually wanted to do it as a this winter project, I am glad I didn't get stuck out on the road and here's my chance to do it now!! Thanks! :)
 
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