Relay Wiring

[Solina Dave]

I'm considering wiring in a relay to my charging system to achieve a more positive relationship between my Regulator/Rectifier and my battery. Is this how I'd wire it? And do you think it's a good idea?

[SnoBrdr]

I'm considering wiring in a relay to my charging system to achieve a more positive relationship between my Regulator/Rectifier and my battery. Is this how I'd wire it? And do you think it's a good idea?

scan0002.jpg

Why would you do that?

[Solina Dave]

Why would you do that?

I'm just considering the possibility. Right now my bike is in hibernation until the spring with a defective stator. I have been experiencing higher than needed charging voltage (15.0 to 15.3 volts) over the past season and I'm just trying to plan ahead. I seemed to have read that taking the black pilot wire out of the circuit through the ignition switch was a possibility. I'm open to constructive criticism.

[WingAdmin]

This is a common modification - I did it to my own GL1100.

The problem is that the voltage on the "sense" wire that goes to the regulator gets low. This wire is used by the regulator to determine what the battery voltage is. If it is too low, it boosts the regulator output, if it is too high, it lowers the regulator output. That's how it knows how to properly charge the battery.

That sense wire comes from the ignition switch, so that when the bike is turned off, the regulator is turned off, too. The problem is that the regulator wants to monitor the battery voltage, but the voltage it sees on the sense line first goes through a fuse, a bunch of connectors, a bunch of wire, and an ignition switch. Any and all can and do introduce resistance that lowers the apparent voltage, and with the passage of years, dirty and worn switches and connectors create more and more resistance.

This makes the voltage that the regulator sees on the sense line appear much lower than it actually is at the battery. On my GL1100, when the battery was showing 12 volts, the sense wire was seeing somewhere around 10.5. In response, it would boost the output of the regulator - with the end result being that the battery was getting overcharged with 15 or 16 volts. This would boil the electrolyte out of the battery, and shorten its life.

So you cut the sense wire, and instead of feeding it to the regulator, you feed it to the coil of a relay, with the other end of the coil going to ground. The relay then switches a wire that goes directly to the battery, to get the most accurate reading possible. The end result is proper voltage and proper charging.

MAKE SURE that you insert a fuse on that line that runs to the battery, and locate the fuse as close to the battery as possible. A 5 or even 2 amp fuse should be more than enough. Without that fuse, a short or pinched wire could cause a fire.

[Solina Dave]

That's an excellent write-up WingAdmin. I think this is the first time I've had the cause and the cure clear in my mind. I was close, but your write-up kind of confirms it. I'll definitely install that fuse you mentioned.

Thanks again..........................Dave

PS.........I realize I gave the impression that I have a regulator/rectifier combination already installed. That's not the case. Do you have a recommendation for a reliable unit, and possibly a reliable source. Or are they all about the same?

[Rednaxs60]

Did this mod on my bike earlier this year after perusing the threads about it on this and other forums. Also changed the 12Vdc wires to the coils so that the voltage to the coils is closer to battery voltage much like you want to do for the RR.

Here is a picture of the final install:

The kill switch controls the relay and the system works as if it was wired from the factory.

Good luck

Cheers

[ekvh]

I have done it to three 1000's all brought voltages of 15-16 down to proper 13-14+. I did mine similar to the second schematic with the reading near the battery but after the solenoid.

[WingAdmin]

That's an excellent write-up WingAdmin. I think this is the first time I've had the cause and the cure clear in my mind. I was close, but your write-up kind of confirms it. I'll definitely install that fuse you mentioned.

Thanks again..........................Dave

PS.........I realize I gave the impression that I have a regulator/rectifier combination already installed. That's not the case. Do you have a recommendation for a reliable unit, and possibly a reliable source. Or are they all about the same?

The OEM regulator/rectifiers really do work quite well, even after all these years, but if I were to use an aftermarket unit, I would source a Shindengen unit - they cost a bit more, but are well known as excellent, reliable and efficient regulators.