Broken Voltage Rectifier.. I think?

[reubs]

Hi all, I'm new here.

To start off, a little about myself: I live in Ireland and I bought a 1995 BMW F650 Funduro about a week ago, love riding it so far!

Today I fitted Oxford heated grips and took the bike out for a test ride in the cold. I noticed the grips weren't getting warm and when I glanced at the controller, I saw the battery saver mode light flashing, indicating the controller had detected battery voltage below 11.5 V. Up until this point I didn't think there was anything wrong with the bike but then I got a bit worried.

I did a good search of the forum and performed the tests advised to check the Voltage Regulator. Here's what I've found: All wires from the VR are fine as far as I can see. Battery voltage with bike off: 11.6 V, voltage at idle with lights and grips off: 12.2 V, voltage at 3000 - 4000 RPM with lights and grips off: 12.4 V, voltage at 3000 - 4000 RPM with lights and grips on: 11.6 V, battery dropped to 8.5 V on startup.

It seems like the VR is gone bad (and battery not great either) based on what I've read on the forums, but is this definitely the problem before I spend about €100 on a replacement part or is there anything else I should do?

[Tutunui]

Hi Reubs, the voltage you measured is definitely too low. You can measure the voltage (AC) between the yellow cables which go into the rectifier, should be about 40 V with engine running. Most rectifiers die with the voltage increasing, but some also die with no charging. If you get voltage on the yellow wires but none between the red and brown on the rectifier it is possibly a dead rectifier.
Do not forget to check all connectors at the rectifier (the green/red and the 3 yellows). Good luck,
Horst

[stevedixey]

Look for my post https://www.f650.co.uk/forums/showth...449#post243449 31-05-2016, 08:47 PM

https://www.youtube.com/watch?v=JqE-Qw0PfF0&feature=youtu.be

http://faq.f650.com/FMainIndex/Electrical.htm

You can get poor connections. If the wires feel "stiff" you might find evidence of overheating due to dodgy connection block pins.

I ordered a unit from the USA, a Shindengen MOSFET unit, and it is a quality unit.

Bought from motoelectrix.com and they sell on E-Bay

[reubs]

Hi Reubs, the voltage you measured is definitely too low. You can measure the voltage (AC) between the yellow cables which go into the rectifier, should be about 40 V with engine running. Most rectifiers die with the voltage increasing, but some also die with no charging. If you get voltage on the yellow wires but none between the red and brown on the rectifier it is possibly a dead rectifier.
Do not forget to check all connectors at the rectifier (the green/red and the 3 yellows). Good luck,
Horst

Ok, measured between the 3 alternator cables and getting 20V on idle in all 3 and about 60 V at maybe 3-4000 rpm in all 3. Resistance between any two was about 0.4 ohms. Haven't checked between the red and brown (mine are red and black, it's not the original) while they were disconnected from the battery but I have checked the battery with bike running and the voltage does increase with revs slightly. Pretty sure its the VRR now.

[reubs]

Look for my post https://www.f650.co.uk/forums/showth...449#post24344931-05-2016, 08:47 PM

https://www.youtube.com/watch?v=JqE-Qw0PfF0&feature=youtu.be

http://faq.f650.com/FMainIndex/Electrical.htm

You can get poor connections. If the wires feel "stiff" you might find evidence of overheating due to dodgy connection block pins.

I ordered a unit from the USA, a Shindengen MOSFET unit, and it is a quality unit.

Bought from motoelectrix.com and they sell on E-Bay

Thank you, useful info. Checked the voltage and resistance on the yellow wires, see above post. None of the wires felt stiff to me although I haven't pulled the loom apart, only checked where they exit the loom by the VRR and where the alternator wires go into the engine casing (if that's the right name). Have ordered a cheap eBay unit cause I'm poor. Hopefully it does the job.

[Tutunui]

Hi, you should consider moving the new rectifier to a better vented place, as it overheats and does not last long under the seat. I soldered longer wires on the unit and screwed it on the right side to the plastic under the rear seat. I can send a photo if you wish.

[reubs]

Yes I was planning on doing that, pictures of your solution would be great. I have seen 2 possible locations from faq.f650.com as well but the more options I have the better I guess! Still waiting on the part, in the mean time the bike's going well just no heated grips

[stevedixey]

See my post about re-siting the VR (photos are in the thread)

https://www.f650.co.uk/forums/showth...-(again)/page2

[Tutunui]

I have attached a phote, I hope