Regulator charging issues. Help Urgent

[Urban_Legend]

Hi all.

I finally got my starter issues fixed, but on my first test ride, I noticed the volt gauge reading at 17.8v at highway speed.

I got home and put the multimeter on the battery.
14.7v at idle and actually went up to 19v at 4000rpm.
It was suggested to me that the Regulator was faulty and to do the Bosch Regulator mod. Did that and initially got the same results as above. Had it suggested that I had it wired up backwards, so switched the wires and got a reading of 11v at idle and 12.4 v at 3000rpm.
I have gone through the entire wiring loom and found no pinched wires or shorting out. I did find the joiner just before the main 30amp fuse was a bit melted, so replaced that and cleaned all connections.

This morning I disconnected the Bosch mod and installed an OEM reg from my old 1100 alternator. And got the same results as listed above.

So help please. Could a dodgy battery cause these issues. My current battery is 2 years old. Has been run flat many, many times and over the last few weeks has had to do a lots of high load cranking to sort the starter clutch issue.

Mark

[Urban_Legend]

Update. Have tried 3 regulators (2 OEM and 1 aftermarket) all are now returning voltage, with motor running at 3000rpm, of 12.6v (lights off)and 12.38v with lights on. These are stable volts with no drop over time. At least its not spiking now.

Mark

[CutterBill]

Maybe this will help...

You have two wires coming from the alternator: a fat red wire and a skinny brown wire.  The red wire is the alternator output; the brown wire is the Sense wire. It senses the voltage in the system. The regulator looks at the voltage coming in on the brown Sense wire, and adjusts the output of the alternator to be around 13.5- 13.8 volts.

If there is high resistance somewhere in the sense wire circuit, there will be a voltage drop at the regulator. In other words, there might be 13.8 volts in the system (and going to the battery) but the regulator might "see" only 10 volts. The regulator doesn't understand that there is a bad connection or a dirty switch somewhere, all it "sees" is low voltage, so it keeps cranking up the output of the alternator until it sees the proper 13.8 volts. So now the alternator is putting 19 volts into the wiring harness (and battery) but the regulator sees only 13.8 volts.  The regulator thinks everything is good, but clearly it is not.

If you have high voltage at the battery (bike running of course), then you have a bad/dirty/corroded connection somewhere in the Sense circuit. Find it, fix it.
Bill

[Urban_Legend]

Thanks Bill
Another member sent me some photos from a service manual on faultfinding the charging system. Seems some of the ohm amd continuity reading are a bit out. So leaning towards some issues with the alternator itself. It also seems to be not charging the battery at all now. XRay (Ray) sent a link to me from a post about 12 months ago that has very similar issues, that also turned out to be the alternator.
A fellow FJer has a spare alternator that he is gong to loan me at check our theory tomorrow.
Mark

[Mike m]

Bill great way of simplifying the fj charging system. Kudos to ya!!

[Mike 86 in San Dimas]

I had trouble with out of spec voltage at Battery. Chased the problem a bit. Finally replaced battery... everything back to normal.
Mike

[TomJK]

Hi
Check the plug and cables, mine were corroded and gave way to much resistance, I will replace plugs and cables, otherwise battery and other parts wil suffer while getting too high voltage.
Cheers, Tom.