82 over charging

[bikrbob1]

My 82 charges at 15 vdc and seems to be cooking my batteries about every 2 years.
Other than that it runs fine, I just had it in Daytona and pulled my Mini Mate down there with it.
Is there an aftermarket rectifier/regulator that would solve this issue?

[DenverWinger]

Three more measurements to make before you condemn the regulator, do all measurements at 3000 RPM:

Measure volts between the green wires at the regulator and battery negative terminal. Should be very nearly zero. Voltage found here suggests a bad ground somewhere

Measure volts between the red wires at the regulator and battery positive terminal. Again should be very nearly zero. Voltage difference here is unlikely to cause overcharge though

Measure volts between the black wire at the regulator and battery positive terminal.

Most common fault is voltage drop at the black wire, you might see a volt or more. The reading on the black wire should reflect how may volts of overcharge - The black wire is the voltage "Sense" for the regulator. If there's a significant voltage reading between the battery pos terminal and this black wire, the regulator will overcharge by that much.

There's a fix for this using a relay.

Take these measurements and report back.

[bikrbob1]

Thank you for the response. I will check it this weekend.

[WingAdmin]

My 82 charges at 15 vdc and seems to be cooking my batteries about every 2 years.
Other than that it runs fine, I just had it in Daytona and pulled my Mini Mate down there with it.
Is there an aftermarket rectifier/regulator that would solve this issue?

This is a pretty common problem. The sense wire that the regulator uses to adjust the voltage runs all the way up to the key switch. After 40 years, the wire, connectors and so on that go from the battery, fuse block, up to the key switch, then back down to the regulator have gotten old and dirty. The result is that some resistance builds up. So while the battery might be at 12 volts, by the time it winds its way through the bike and to the regulator, it's showing maybe 10 volts. The regulator says, "oh, that's too low" and jacks up the voltage to compensate - and that's why instead of 13.8 volts, you see 15 or 16 volts at the battery, which will 100% cook your battery.

How I fixed this on my 82, and how I suggest you fix yours, is to connect a new, fused wire directly to the positive terminal on the battery. Run that through a relay, and from there to the regulator in place of the sense wire coming from the key switch. Then use that sense wire from the key switch to actuate the coil of the relay.

That way, when you turn the key switch on, it closes that relay, which supplies voltage DIRECTLY from the battery to the regulator. The regulator sees the correct voltage, and makes the correct adjustments. This fixed the problem on my 1100.

[bikrbob1]

I have relays, what size wire are you using?

[DenverWinger]

Very little current goes thru the sense circuit, any old wire you have handy is ok, 20 GA or better would be fine. Use a 2 or 5 amp fuse in the wiring description above.

[bikrbob1]

Thank you. I will try to get that done this weekend.

[bikrbob1]

So I ran the test, the first two showed a -.08 and a -.02.
Third test showed .63 positive at 3000 RPMs.
At idle, the bike puts out 15 V.
Not sure if this is related but now when I turn off the key and remove it unlocked I’m showing 3 V on my voltmeter on the bike.

[DenverWinger]

Third test showed .63 positive at 3000 RPMs.
At idle, the bike puts out 15 V.

So that's a .63 volt reduction in charging voltage if you apply the relay fix.

[bikrbob1]

Ran out of time today. It’ll have to wait until next weekend.
Thanks for your help.

[CT1100]

In 2020 I also came to realize that I had an overcharge problem with my 83 gl1100. The stator was within spec so I went ahead and replaced the regulator/rectifier. That turned out to be a waste of money.

Do yourself a favor and if you have had any overcharging/dry battery problems in the past just replace the battery before you go any further. It may show 12 volts on the charger but than fall on its face once any type of load is applied.

The solution was in this thread.
viewtopic.php?f=4&t=42125

The modification was not as difficult as I thought it would be. Just study the thread while looking at the diagrams. Remove your seat and false tank. Find the R&R on the left side and cut the black sense wire half way between the unit and the factory wire connector. I like this solution because this was the only cut to the factory wiring and would be easily repaired if this modification did not work (but it did). Now lengthen both black wires to reach your new relay location. Make a fused wire that will go from your positive terminal of your battery to your new relay.

I was able to mount a waterproof relay to an existing bolt to the left of the battery box and wired it following the diagram in the thread.
Pin 85 to ground. Just make a pigtail and ground it using the relay mounting bolt
Pin 87 to the cut half of the sense wire going into RR
PIN 86 to the cut half of the sense wire coming from the connector
Pin 30 to the + battery terminal

My results were as follows:
Voltage at battery with ignition key off 12.49
Voltage at battery with key on 11.9
Voltage at black sense wire with key on (engine not running) before modifications 11.0 after mod 11.9
Voltage at battery engine running at idle before mod 14.4 after mod 12.7
Voltage at battery engine running at 3,500 rpm before mod 15.45 after 14.22

Hope this helps

Chris