Switched power lead

[ArthurKnowles]

I'm going to be installing some accssories on my 96 R1100RT and plan to put a fuse box under the seat. I'd like it to only be active when the motorcycle is running. Is there a lead that only provides power, or ground (I can use either one), when the motorcycle is runnning?

On my Concours, there is s blue lead that is only live after the motorcycle starter has been enganged. Something like that would work well too.

[PGlaves]

I am not aware of a switched lead that is capable of providing very much power. If you are talking about powering a radar detector or a GPS there are options: If you are talking about powering lights, heated clothing, or anything else that requires real wattage then what you will need to do is energize a relay with switched power but pull the real amperage through the relay fused straight from the battery.

[ArthurKnowles]

Actually, I'm just looking for a lead (either positive or negative) that is only live once the motorcycle has started. I will use that lead to turn on a relay. The relay will then energize the fuseblock so my accessories get power.

All relays require a trigger wire (positive) and have a ground (negative). Which is why I can use any lead with a positive or negative value so long as it is only live once the motorcycle is started. That way, when the motorcycle is turned off I will not have to worry about the battery discharging from a live accessory.

[PGlaves]

In that case I would draw power for the relay coil from the circuit to the tail light. I don't have the wiring diagram but you can trace it forward to a convenient location under the seat normally.

[ArthurKnowles]

Hmm, that might work. But isn't that circuit live in Park mode? I'm not sure I'd want the accessories live if I needed to use Park mode. Meaning, if I'm stranded I want my tail light to last as long as possible so it (& me) don't get hit by anohter driver.

[PGlaves]

Hmm, that might work. But isn't that circuit live in Park mode? I'm not sure I'd want the accessories live if I needed to use Park mode. Meaning, if I'm stranded I want my tail light to last as long as possible so it (& me) don't get hit by anohter driver.

It probably is. Unless you use "park" a lot, just turn them off.

In my almost 600K miles I've never used the park mode so didn't even think about it.

[beeryboats]

I did exactly what Paul said. I ran a relay off the tail light circut, with a switch, for my driving lights. It's all under the seat. So if I need to I can lift the seat, turn off the lights, and just run the normal stuff off the switch. I've heard some not so great things from some about my $14 Walmart lights, but I love them. If one goes bad, I'll spend the $14 bucks and buy another pair.
Jay

[ArthurKnowles]

I was just outside looking at my fuse box. I see that there is some empty spaces. Has anyone tried to add another row of fuses to the existing fuse box? Looks like there is a spot for another bank right next to the existing bank. And in fron of the existing bank of fuses is an empty spot that might be able to hold an additional relay. If it is possible, I could order the parts from BMW or perhaps buy a used fuse box on eBay and scavange the parts.

I'm just trying to consider the available options before I purchase a fuse box and/or instalaltion harnesses.

[bmwmick]

I was just outside looking at my fuse box. I see that there is some empty spaces. Has anyone tried to add another row of fuses to the existing fuse box? Looks like there is a spot for another bank right next to the existing bank. And in fron of the existing bank of fuses is an empty spot that might be able to hold an additional relay. If it is possible, I could order the parts from BMW or perhaps buy a used fuse box on eBay and scavange the parts.

I'm just trying to consider the available options before I purchase a fuse box and/or instalaltion harnesses.

Art,
You could use the D+ output from the alternator to energize a relay. Feed the battery through that relay to whatever accessories you want to p;ower. The common Bosch/Hella 30 relays have 88-100 Ohm coils so that is about 0.165amps. I've used this for other things and it works very well.
The relay will not energize till the engine is running and the alternator is supplying 12V on the D+ terminal (blue wire

[ArthurKnowles]

Thanks, that sounds like it would work and do what I want. Now I'll just have to find that wire. I'm a very new owner of an older 96 RT. But I do have the OEM manuals on PDF and a Haynes manual so I'm sure I'll be able to figure it out.

[bmwmick]

Thanks, that sounds like it would work and do what I want. Now I'll just have to find that wire. I'm a very new owner of an older 96 RT. But I do have the OEM manuals on PDF and a Haynes manual so I'm sure I'll be able to figure it out.

Art,
There is a single blue wire (0.5mm) on the D+ terminal on your bike. Tap it right there with a 1/4" spade add-on connector. I have the same bike.