Should sense wire of Honda R/R be grounded?

[ekabil]

I was just saying that in order to detect voltage, there must be a current passing through whatever is doing the detecting. When you put your multimeter leads on two point of a wire, your multimeter acts like a parallel component in that circuit. It draws a small amount of current, and by applying a known resistance, the multimeter can calculate voltage.

If current must pass through the voltage sensor, then current must pass through the sense wire in order for the RR to monitor voltage. Because current flows from positive to negative, if you connect the sense wire to the negative battery terminal, no current will flow. There is no potential difference, so no current.

That is why you must put the sense wire on something with a positive voltage, or at least more positive that wherever the RR is grounded, such as the positive battery terminal.

I think if you guys read what I wrote again you'll see that I'm not saying to put the sense wire on the battery negative and that I am in fact agreeing with, I think, all of what you say I'm just trying to explain why we connect the sense wire where we do. You are making a circuit that goes through the RR.

"Well, sort of. To be more correct, the sense wire detects the difference in potential in order to determine voltage. Think of how your voltmeter works. You have to place the black wire to a ground and the red wire to the 12V wire being investigated."

potential = voltage. If you measure the potential, you know the voltage. Voltage is potential energy per charge, but generally the terms potential and voltage are interchangeable.

I said
"The sense wire is grounded to the negative battery terminal through the RR ground. That's how it senses the voltage. ..."
This is true. The sense wire forms a circuit that goes from a point with positive voltage, such as a hot wire or the positive battery terminal, through the sense wire, through the RR, and finally to the negative battery terminal. Because this circuit draws current (however small) the voltage can be determined. Anyone with a little knowledge of circuits could then take this understanding and apply it to understand why connecting the sense wire to the negative battery terminal is equivalent to running a wire from the negative battery terminal around the frame and then back to the battery terminal. In other words, pointless.

[Steve]

Believe it or not, there are a few of us here that actually know how this stuff works. If I remember correctly, Koolaid_Kid is an electrical engineer, I am only an electronic technician, but I deal with electronics on million-dollar pieces of equipment on a regular basis, I understand how it works.

However, you have to understand that for a LOT of the guys that are reading this, they will see what they think they see, so you really have to be rather detailed and specific.

Example: (highlights are mine)

I think if you guys read what I wrote again you'll see that I'm not saying to put the sense wire on the battery negative and that I am in fact agreeing with, I think, all of what you say I'm just trying to explain why we connect the sense wire where we do. You are making a circuit that goes through the RR.

...

I said
"The sense wire is grounded to the negative battery terminal through the RR ground. That's how it senses the voltage. ..."

When you tell somebody "ground that light to the negative terminal", he is going to connect a wire to the negative terminal. When you tell him that "the sense wire is grounded to the negative battery teminal ..." he is going to connect it to the battery negative terminal.

Strictly speaking, EVERYTHING on the bike is grounded through the R/R ground, or at least connected to it.

Please read our statements again, nobody said you were wrong. We were just trying to emphasize that that is not the point where you connect the sense wire.

Hopefully, all this bickering over semantics is not keeping amontyg from making a few quick tests and getting back to us.

.

[barnbiketom]

the reason you are reading 12 volts on the unconnected sense wire, to ground, is because it is a bias voltage from the RR.. it acts upon what is pushing against it and the RR acts accordingly.

it is not a valid test to do anyways.

just hook the sense wire to a SWITCHED + voltage (best) or the battery + terminal if you do not mind a wee bit of drain on the battery at all times..

[koolaid_kid]

Thanks, Steve, and you are correct.
Ekabil, when we post here, we need to be careful to write to the level of the audience, and leave out anything that might be confusing. For what I can see, amontyg just wants to know what wire connects where. When that question is answered, we are done. Thanks.

[cableguy]

The leg bone's connected to the knee bone and the sense wire should be connected to a 12v sourced that is on with ignition.

[duaneage]

I have the sense wire attached to the orange wire right before the brake light switch. When the ignition is on and the bike is not running I get 12volts from this point to the positive battery terminal. If I disconnect the sense wire from the orange wire I get 12 volts from the orange wire to the negative battery terminal. Does this make sense? Should this point see a complete reversal in polarity when the sense wire is connected?

Just to be clear I have the green wire running right to the negative battery terminal. The red wire is connected to the original red lead for the original R/R. I have then run one of each of the three wires from the stator into one of the three yellow wires in the R/R. All connections have been soldered.

This is how I would recommend installing it. See my diagram on the sig line below at the end of the document.

[ekabil]

Ok, I do see how my explanation could have been misinterpreted. In defense of the "audience" though I would hope that they would read the rest of a post before doing things to their bike. I thought that if I or we explained the reasons behind the suggestions then the readers could be benefited in the future. It was also for my own benefit, to verify my own knowledge and understanding. So, sorry amontyg for derailing your thread.

You might want to check out my thread on "installing a voltmeter" its somewhere on the front page, in there I posted a diagram of a relay. Sometimes, wherever you connect the sense wire is going to have a voltage that is lower than the actual battery voltage, because of resistance from corrosion. This is especially common on older bikes like ours. So the ideal place for a sense wire to be is on the positive battery terminal. However this would slowly drain the battery all the time, even when the bike is off. A relay is going to let the sense wire read directly from the positive terminal, without draining the battery. If you hook up a relay the right way, it will turn off current to the sense wire when the bike is off. PM me if you are interested in doing this. If your battery is being overcharged, then this would definitely help you.