Best point to wire in accessories

[Elijah Johnston]

Good morning all-
So I'm currently undertaking a series of wiring projects on my girlfriend's 1982 GS450T and 1980 GS850GL. The harnesses are relatively similar, and I was able to figure my way through it on the GS850, but I'm still not 100% on the 450. I have basic knowledge of electrical wiring, and am reasonably familiar with both systems.
My plan is to attach a hot pigtail to a switched live, preferably from the ignition switch, and run it to an auxiliary fuse box, from which I can attach accessories such as heated grips, USB chargers, etc.
My first foray, involved creating the switched live from the orange wire that comes out of the ignition switch, which appears to power almost all the main circuits of the bike.
When the key is on, and my "toys" are attached, they all work. When I start the engine however, they don't. My voltage monitor (also connected to the aux fuse box) shows a stead 13.5 volts, but the LED indicator light seems to be blinking rapidly (and I mean so fast it almost appears steady.) The heated grips however, which I believe rely on a CONSTANT and steady DC input, don't function. The LEDs on them that indicate power will sporadically flash, indicating they are receiving power in bursts.
I've been racking my brain trying to figure this out. We noticed that at over 3k RPMs, the LEDs stop the rapid blinking, and become steady, and at that point the grips function as normal.
Studying the wiring diagram tells me that the ignition coils are (at least somewhat; through the stop switch) connected to this orange main hot line. Is it possible that their draw on the system at idle is preventing a steady DC output for my aux box at idle? And if that's the case, what would be a better wire to attach the source lead for my aux box?
Further study of the wiring diagram leads me to consider attaching to the brown lead from the ignition. It appears to just run to the brake/tail light.
Anyone have any input here? I'm doing my best to not ask dumb questions, but I suspect SOMEONE here has gone through this exact process before.
Thanks for any assistance!

(Haven't figured out how to add a signature yet.)
Garage includes:
1999 Suzuki GSF Bandit
1982 Suzuki GS450T
1980 Suzuki GS850GL
1982 Yamaha Virago XV920.

[Steve]

The fact that your situation clears up by 3000 RPM tells you that it's simply not producing enough current until that point. With the stock stator and regulator, the stator will be producing as much current as it can, all the time. The output increases with engine speed and just barely matches the load of the stock bike somewhere between 2000 and 2500. Your additional load will require extra speed for more output.

I also have a few "toys" on my 850, but none of them draws much power. I have a CB radio that includes intercom for the passenger, XM radio, GPS and a wire for my heated jacket. The only one that draws voltage down very much is the heated gear.

The only thing I would use that brown wire for would be to trigger a relay. Yes, it only feeds the tail light, but it is fed by the headlight fuse. If the extra load you add happens to exceed the limits of the fuse, you just <might> be finding your way around a curve at night with no lights. Not fun. Do you really need to ask me how I know?

There isn't much you can do to increase the output at lower engine speeds, but switching your regulator to a more-modern series style, like the SH775, will help save your stator from overheating when it's not producing as much. Sounds counter-intuitive, but the stock regulator works by shunting any excess back to ground, meaning that the stator is putting out full output all the time. The SH775 interrupts the current to regulate it, meaning that the average output is lower.

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[Elijah Johnston]

Thank you very much for your feedback, Steve, I appreciate it.
I had to replace both the stator and R/R unit six months ago or so, I have a voltage monitor mounted also. So neither the stator nor R/R are stock at this point. I also bought a SH775 a week ago or so, spent the afternoon crimping spade connectors to it. (12 gauge wire, might be overkill, but who's counting.)
I think part of my confusion, (and the reason I hadn't gotten there yet) was the fact that my voltage monitor showed 13.4ish volts at idle, which I assumed, naively, to be plenty for the system, and didn't consider that while voltage may be there, current may not. I guess that makes sense though.
Also, this particular '82 GS450 didn't come with any fuses when we bought it. Not a one. So I recently installed a 15 amp main fuse, in the red wire between the battery and ignition, but nothing else on there is fused, before the aux fuse box I installed. It might make sense to buy a 5 bar fuse block, like the one on the 850, and spend a weekend setting that up to more closely match the 850.
I've had no issues whatsoever running gear off the 850. It also has voltage monitor, heated grips, and multiple chargers. Its next big upgrade is also likely to be a SH775.
Thanks again for your reply, that's illuminating.

[Gorminrider]

I just create a separate circuit for auxiliaries direct from Battery positive. You can tap to where the battery attaches at solenoid (a main fuse for this aux would be very near here!) and from there goto a fuse-bus . This circuit will not be influenced by the key. It is always "live". If you wanted it so, Steve's relay tapped from brown or orange would do it.
I have a heated vest and/or a gps "always live" has not been a problem because I like the gps on when stopped and the vest unplugs. Your heated grips are the only reason I'd suggest a relay or maybe a separate switch for that circuit.
As to blinking leds and all that I would not know about your device...it does seem it might be indicating a low voltage and an automatic shutdown of it self from your description...

"Ground" is the frame anywhere behind the forks.

originally, the 450 had a bifurcated red from the battery + terminal. A thick UNFUSED red went to solenoid, a smaller gauge wire connected to the rest of the bike through a single fuse, thence to the key which switched it to orange etc etc

PS do consider your ignition switch may be having trouble with the extra demand. Not common but it happens. also of course any connections between battery + and the key and also ground connections. I've always considered red and orange to be a bit light gauge to add loads to, so "sistering" them with another wire as parallel might be an option you might like.