Honda R/R Sense wire - Direct to Battery?

[mostholycerebus]

My bad, found it.

[salty_monk]

I think it might drain the battery if you wire it that way.. I don't remember why & this might also be BS, you should be able to find some info on it, that's where i will have read it.....

I think most people connect into the rear brake light feed. An ignition switched live.

Dan

[Griffin]

I connect it to the oil pressure sensor wire.

[Billy Ricks]

Brake light before the rear brake light switch. Taillight wire or any other switched power source.

[mostholycerebus]

Yeah im gonna wire it in, now I just have to interpret the tangle of wires behind my battery box.

[Dave8338]

Tail light for me...

[Suzuki_Don]

You can connect the sense wire directly to the "+" on the battery, but you need to do it through a relay & inline fuse because these R/Rs are designed to be switched, as they draw parasitic current when the bike is not running which will flatten the battery eventually.

This gives better regulation than the sense wire being wired into the harness somewhere. If the sense wire is connected to the harness somewhere then that is the reference point used (and this could include voltage drop between this point and the battery). The battery is then being charged (over charged) according to what is happening at the brake light switch for example.

If the sense wire is connected directly to the battery it is sensing exactly what is going on there and the regulator responds accordingly.

There are some good explanations on this topic by BAKALORZ.

[mostholycerebus]

You can connect the sense wire directly to the "+" on the battery, but you need to do it through a relay & inline fuse because these R/Rs are designed to be switched, as they draw parasitic current when the bike is not running which will flatten the battery eventually.

This gives better regulation than the sense wire being wired into the harness somewhere. If the sense wire is connected to the harness somewhere then that is the reference point used (and this could include voltage drop between this point and the battery). The battery is then being charged (over charged) according to what is happening at the brake light switch for example.

If the sense wire is connected directly to the battery it is sensing exactly what is going on there and the regulator responds accordingly.

There are some good explanations on this topic by BAKALORZ.

That's what I figured, the positive terminal would give the regulator the most true reading, but forgot it will continue to draw. I just looked at it and after a week of sitting, the battery doesn't seem to have dropped much. Plus my taillight doesn't use the easy-to-add bullet terminals, but a wiring harness that would be more difficult, and less professional, to hack into. I'm gonna wire it in directly to the battery terminal instead. I can wire in the fuse just fine, but what kind of relay should I put in there?

[posplayr]

Sense Wire

You can connect the sense wire directly to the "+" on the battery, but you need to do it through a relay & inline fuse because these R/Rs are designed to be switched, as they draw parasitic current when the bike is not running which will flatten the battery eventually.

Apparently the Honda R/R designers did not think to make the sense input high enough impedance (resistance) to make this current drain a non issue. That is surprising as it would only take about 10K ohms to make this an non issue. I have never measured it myself this current draw myself but I might actually check it.

Regardless to be on the safe side, the sense wire simply needs to be located at a point that is disconnected from the battery when the bike is at rest. That could be the output of a relay or attached to the tail light wire as I think is recommended by Dunage.

There should be no reason to fuse the wire.

Pos

[mostholycerebus]

I just wired it through the taillight, as I have no relays or fuse holders laying around here. Unfortunately, there does seem to be some resistance now. When I had the sense wired direct-to-battery I was getting a solid 13.5v at 1500rpm, and a solid 14.5v at 4000rpm. Now i seem to get 15v regardless of rpm. I think i'm gonna try cleaning the connections and using fewer crimps, maybe just get a 3-way or something instead of the bullet connectors that the R/R came with.

[posplayr]

mostholycerebus

Unfortunately, there does seem to be some resistance now. When I had the sense wired direct-to-battery I was getting a solid 13.5v at 1500rpm, and a solid 14.5v at 4000rpm. Now i seem to get 15v regardless of rpm.

An therein lies the problem. I will check a Honda regulator that I have with a high accuracy amp meter to see what the draw really is. That sense wire should be high enough impedance to draw virtually nill and you should be able to hook it right to the battery.

Using the tail light you are just that much further from the battery and are now affected by voltage drops due to tail light current drops. Pretty sure that tail light does at least through the ignition switch and possibly through a left hand control depending on the age of your bike.

We are now back full circle to Don's suggestion Use a relay . However the logical thing is to use a relay from the Coil Relay mod.

Another option is to put the bike on tender if it sits for an extended period of time.

Jim

[bakalorz]

You can connect the sense wire directly to the "+" on the battery, but you need to do it through a relay & inline fuse because these R/Rs are designed to be switched, as they draw parasitic current when the bike is not running which will flatten the battery eventually.

Apparently the Honda R/R designers did not think to make the sense input high enough impedance (resistance) to make this current drain a non issue. That is surprising as it would only take about 10K ohms to make this an non issue. I have never measured it myself this current draw myself but I might actually check it.

Regardless to be on the safe side, the sense wire simply needs to be located at a point that is disconnected from the battery when the bike is at rest. That could be the output of a relay or attached to the tail light wire as I think is recommended by Dunage.

There should be no reason to fuse the wire.

Pos

Thats highly irresponsible advice.
Did you even read the post you quoted ?
I highlighted the relevant parts for you so you don't miss it again.

If you do it via a relay, the whole point of the relay is to run that wire directly to the battery and avoid any sharing of that path with high current loads.

In that case you darn well do need a fuse unless you want to risk your bike catching fire.

Sheesh.

P.S. for the original poster, any 12 volt automotive relay will be fine as far as the current rating current goes.
There were some discussions in other threads regarding vibration resistance of the various relays available.

For a fairly detailed description of how to connect the relay see post 35 of this thread.

If that doesn't make it clear to you, I remember that there is also somewhere a description of how to connect it using the terminal numbers on the most common relays, but I couldn't find it in a brief search.

[posplayr]

Bakalorz,
Please don't screw up this thread as well. Sheesh. Everything was nice a friendly till you butted in.
Jim

Thats highly irresponsible advice.
Did you even read the post you quoted ?
I highlighted the relevant parts for you so you don't miss it again.

If you do it via a relay, the whole point of the relay is to run that wire directly to the battery and avoid any sharing of that path with high current loads.

In that case you darn well do need a fuse unless you want to risk your bike catching fire.

Sheesh.

P.S. for the original poster, any 12 volt automotive relay will be fine as far as the current rating current goes.
There were some discussions in other threads regarding vibration resistance of the various relays available.

For a fairly detailed description of how to connect the relay see post 35 of this thread.

If that doesn't make it clear to you, I remember that there is also somewhere a description of how to connect it using the terminal numbers on the most common relays, but I couldn't find it in a brief search.

[mostholycerebus]

Ok, well i plan on installing the Coil Relay mod later this week as well. So, best case would be to use the same relay to handle both the coils and sense wire? I'm using the Autozone relay where IIRC 85 is the ground, 30 is fused direct to battery, and 86 and 87 are to the coils? Which one do I add the sense wire too?

Sorry, electrical work is a bit new to me. I'm kinda handy but I always was taught to leave electrical and transmission issues to pros.

[posplayr]

So, best case would be to use the same relay to handle both the coils and sense wire?

This should be the lowest resistance "switched" path to the battery. Put the sense point right at the output of the relay rather than somewhere else down stream.

Of course your relay mod should be powed by a "fused" source as variously described.

Jim