Suggestion of a good earth point

[DaveWatts]

Hi,

I have a GS1000G which recently had a bit of an electrical fire which I think was because the earth point wasn't very good. Now winter is finally over I am starting again. In my understanding there is an earth from the back of the engine that goes to the negative battery terminal. Then there is a rubber mounted bolt on the front of the battery carrier to which goes the the earth from the electrical side panel (other end bolts to the solenoid) and now the negative from a SH775 reg/rect. To make a better earth (since the idea of earthing only through a rubber mounted bolt is a bit crazy) I was going to run a separate earth wire from the battery bolt to the rear brake reservoir bolt.

Am I forgetting anything here? can anyone think of a better earth than the rear brake reservoir bolt?

Thanks for your help

Dave

[Brendan W]

I've done it this way.
Take the two harness earth wires from above the airbox and put them on a post with the R/R ground wire as close as practical to the R/R
I used a mount screw on the starter solenoid.
A separate wire goes from there to the battery negative as short as practical. The purpose of this wire is battery charging.
The idea is single point grounding SPG where the focus is on getting the return currents to the R/R ground point as directly as possible.
The effect is to reduce the voltage drops in the return to the R/R and let it have a more accurate view of what is happening on the 'grid'.
The brake post seems a bit far away and exposed for my liking.

[DaveWatts]

Hi Brendan,

Yes I read the SPG article and it is interesting and make sense, that is until I read this article about the dangers of directly connecting anything other than the engine and the frame ground to the battery negative.

http://www.w8ji.com/negative_lead_to_battery.htm

This is why I thought to connect all these components to a frame earth point, this frame earth point having the frame to battery earth cable as well. So it will get to the battery negative anyway. The battery negative will then only be connected to the thick engine earth and the frame earth cables.

Cheers

Dave

[Steve]

... To make a better earth (since the idea of earthing only through a rubber mounted bolt is a bit crazy) ...

The bolt is not rubber-mounted.

The bolt goes directly to the chassis, which is a good earthpoint. The battery box is the rubber-mounted item, to minimize vibrations sent to the battery. There should be a steel sleeve in the center of the rubber bushing. That will help ensure good contact between the earth wires and the bolt/chassis mounting point.

.

[Redman]

About the battery-box-solenoid-mount bolt:
Do not think of that as THE ground. Think of that as an item than needs TO BE grounded, same as, say, the tail light needs TO BE Grounded. THe solenoid and the R/R needs to be grounded and they are mounted on the battery box (which most likely is not well grounded), so need to run a ground wire to the battery box (solenoid mounting bolt) in order for the battery box TO BE grounded.

[DaveWatts]

The bolt is not rubber-mounted.

The bolt goes directly to the chassis, which is a good earthpoint. The battery box is the rubber-mounted item, to minimize vibrations sent to the battery. There should be a steel sleeve in the center of the rubber bushing. That will help ensure good contact between the earth wires and the bolt/chassis mounting point.

.

Right, but the only contact between the bolt and the frame is in the (rusted out) screw threads and maybe the steel sleeve, since the bolt squashes down on the rubber part when tightened I don't think much bolt-sleeve-frame contact is being achieved. I prefer a exposed metal surface for the earth that I can bolt the ring terminal flush with.

[DaveWatts]

About the battery-box-solenoid-mount bolt:
Do not think of that as THE ground. Think of that as an item than needs TO BE grounded, same as, say, the tail light needs TO BE Grounded. THe solenoid and the R/R needs to be grounded and they are mounted on the battery box (which most likely is not well grounded), so need to run a ground wire to the battery box (solenoid mounting bolt) in order for the battery box TO BE grounded.

Ok so the battery plate is grounded on the frame, but in the standard wiring setup the battery is grounded to the engine not to the frame and there is no path from the frame to the battery negative. Maybe the engine and the frame can be considered a single ground wire since the engine is not rubber mounted. Then any return current from the electrical plate will pass through the black/white wire to the frame, through the frame to the engine then back to the battery via the engine to battery negative wire. I think I would prefer a frame to battery negative wire, then make the grounding for the electrical panel from this same point. Done this way the earth from rubber mounted bolt to the frame doesn't matter so much because the frame to battery negative wire provides a return path. The advantage of the stock circuit (engine to battery negative) is that nothing is in the way of the battery and the starter motor, the largest current drawing items.

[gsrick]

Your frame is a ground contact point for everything as long as you have clean metal to metal contact. Battery to engine, engine to frame and all other grounded items also bolt to the frame. You could add a ground strap from the battery to the frame for insurance or assurance if you want. most modern bike use a single ground point in their harnesses, but the battery to engine ground is still there, with no Battery to frame wire. All components have a dedicated ground path in the harness with three or four points ending up at one spot and bolted to the frame.

I'm not sure where the earth term is coming from, since there is really no ground to earth on a bike. Houses, now that's a different matter. I remember seeing my grand father putting a rubber strap that drug the ground on his cars in Maryland, but I'm only guessing at that as being some type of urban legend to rid static electricity? Anybody know of this?

[Redman]

Ok so the battery plate is grounded on the frame, ..............

No. The battery box may not be well grounded to the frame by its mounting. SO that is why need to have a ground wire TO the battery box TO ground it.

Good that you are thinking about this.

THe battery negative has a heavy cable to the back of engine (top of transmission) AND the battery negative also has a smaller black/white that goes into the wiring harness and is spliced into several other back/white wires in the wiring harness, one of those several black/white wires goes to someplace on the frame to make the frame part of the ground (on bikes I am familiar with this place is on top of the frame behind the battery box, near tool tray, can see when take off the seat). Other of those blk/wht wires go to places such as the tail light, the instrument cluster, the head light, the ignotor, the battery box and all the other places that need a ground.

You do need that heavy negative cable to the back of the engine to carry the starter motor current. That place is not so accessable, but needs to be a good connection. (Check it, and clean it up when ever have the rear wheel off. Is easier to get at then.)
Yes, engine is bolted directly to the frame, but thru painted surfaces and such. SO the big negative cable is there directly on the engine to provide the starter motor a good return path to the battery negitive.
If that big negative connection is not good then all that starter motor current (way higher current than anything else on bike) could try to go thru engine to frame and thru the little blk/wht wire (which cant handle it) to battery negative.

I am not at all arguing with you. Just trying to explain some things about the stock setup.
You could arrange things elsewise, but do need the heavy cable from battery negitive to the engine. And do need a ground wire to the battery box (solenoid mount).

.

.

[DaveWatts]

No. The battery box may not be well grounded to the frame by its mounting. SO that is why need to have a ground wire TO the battery box TO ground it.

Good that you are thinking about this.

THe battery negative has a heavy cable to the back of engine (top of transmission) AND the battery negative also has a smaller black/white that goes into the wiring harness and is spliced into several other back/white wires in the wiring harness, one of those several black/white wires goes to someplace on the frame to make the frame part of the ground (on bikes I am familiar with this place is on top of the frame behind the battery box, near tool tray, can see when take off the seat). Other of those blk/wht wires go to places such as the tail light, the instrument cluster, the head light, the ignotor, the battery box and all the other places that need a ground.

You do need that heavy negative cable to the back of the engine to carry the starter motor current. That place is not so accessable, but needs to be a good connection. (Check it, and clean it up when ever have the rear wheel off. Is easier to get at then.)
Yes, engine is bolted directly to the frame, but thru painted surfaces and such. SO the big negative cable is there directly on the engine to provide the starter motor a good return path to the battery negitive.
If that big negative connection is not good then all that starter motor current (way higher current than anything else on bike) could try to go thru engine to frame and thru the little blk/wht wire (which cant handle it) to battery negative.

I am not at all arguing with you. Just trying to explain some things about the stock setup.
You could arrange things elsewise, but do need the heavy cable from battery negitive to the engine. And do need a ground wire to the battery box (solenoid mount).
.

Thanks for the input, you don't sound like you are arguing at all (any way I like a good natured argument ). It's pretty much what I thought, its difficult explaining wiring though and maybe some of my wires got crossed in the explanation.

"AND the battery negative also has a smaller black/white that goes into the wiring harness and is spliced into several other back/white wires in the wiring harness"

I guess it could make sense to connect it direct with the battery negative, (and it seems that the SPG method does do something similar), but the stock wiring in the shop manual is that the black/white wire is connected to the battery box bolt and the electrical side panel on the solenoid bolt.

[Steve]

Please keep one more thing in mind. Unless YOU are the one that took delivery of the bike when it was new, and YOU are the only one that has ever worked on it, please don't accept that what you see is "factory stock".

All of the GSes I have had in my stable over the years have had a large wire from the battery negative terminal to the back of the engine, that is the return path for the large current required by the starter. There have always been another one or two smaller, black/white wires that ground other points on the chassis. If you are using the Single Point Ground (SPG) system on your bike, you definitely need one wire from the battery to your SPG.

On your bike, the battery box is rubber-isolated for vibration control. However, the starter solenoid is mounted to a plate that is bolted to the side of the battery box, so there is a ground wire needed from that plate to either the battery or your SPG. That is typically the second wire at the battery.

If your battery box mount bolt is crushing the rubber grommet when tightened, it's possible that you are missing the steel sleeve in the center. The rubber will be slightly compressed, but should not be "crushed".

Personally, I try to minimize the number of wires attached to the battery. One large and one small wire at the negative terminal is plenty. On the positive terminal, one large wire to the starter solenoid is plenty. Any other needs for direct battery power are taken from the solenoid terminal. This theory is intended to minimize the number of wires that need to be located and attached when replacing the battery.

.

[DaveWatts]

Your frame is a ground contact point for everything as long as you have clean metal to metal contact. Battery to engine, engine to frame and all other grounded items also bolt to the frame. You could add a ground strap from the battery to the frame for insurance or assurance if you want. most modern bike use a single ground point in their harnesses, but the battery to engine ground is still there, with no Battery to frame wire. All components have a dedicated ground path in the harness with three or four points ending up at one spot and bolted to the frame.

I'm not sure where the earth term is coming from, since there is really no ground to earth on a bike. Houses, now that's a different matter. I remember seeing my grand father putting a rubber strap that drug the ground on his cars in Maryland, but I'm only guessing at that as being some type of urban legend to rid static electricity? Anybody know of this?

earth/ground I guess they are used interchangeably because the words mean the same thing outside of the world of electricity. But you're right I should be saying ground.

So without an extra cable from the battery box bolt (which has the black/white attached) the return current from components such as light, coils, etc would have to go via the dodgy bolt connection to the frame and then to the engine then via the engine to battery negative cable back to the battery. This is quite a long route which could be short-cut by adding a ground cable (similar gauge to the engine-battery ground wire) from the battery box bolt to the battery negative, if the engine-battery connection breaks then current could also flow from frame to battery this route instead. So I think it is quite a good idea all round.

[DaveWatts]

Please keep one more thing in mind. Unless YOU are the one that took delivery of the bike when it was new, and YOU are the only one that has ever worked on it, please don't accept that what you see is "factory stock".

All of the GSes I have had in my stable over the years have had a large wire from the battery negative terminal to the back of the engine, that is the return path for the large current required by the starter. There have always been another one or two smaller, black/white wires that ground other points on the chassis. If you are using the Single Point Ground (SPG) system on your bike, you definitely need one wire from the battery to your SPG.

On your bike, the battery box is rubber-isolated for vibration control. However, the starter solenoid is mounted to a plate that is bolted to the side of the battery box, so there is a ground wire needed from that plate to either the battery or your SPG. That is typically the second wire at the battery.

If your battery box mount bolt is crushing the rubber grommet when tightened, it's possible that you are missing the steel sleeve in the center. The rubber will be slightly compressed, but should not be "crushed".

Personally, I try to minimize the number of wires attached to the battery. One large and one small wire at the negative terminal is plenty. On the positive terminal, one large wire to the starter solenoid is plenty. Any other needs for direct battery power are taken from the solenoid terminal. This theory is intended to minimize the number of wires that need to be located and attached when replacing the battery.

.

Your right I should check again for the metal sleeve, it might be missing. With the sleeve contacting bare metal and the washer contacting the sleeve and the round B/W wire terminal bolted on top, this would be a suitable ground.

All I would like to mention is that if the engine-battery cable fails then the only return current to the battery negative will flow through the smaller black/white wires melting them. So I would have the SPG point on the frame and run a thicker wire (same as engine-ground wire thickness) from the SPG to the battery negative.

[Steve]

I'm not sure where the earth term is coming from, since there is really no ground to earth on a bike.

earth/ground I guess they are used interchangeably because the words mean the same thing outside of the world of electricity. But you're right I should be saying ground.

The term "earth" was introduced into the conversation because one of the first responses was from someone outside the USA, where the term "earth" is used as the common collection point that we (in the USA) refer to as "ground".

There might be some detail differences, especially in house wiring, where there is, indeed, an "earth" connection to a copper rod that is buried into the earth. Vehicles do not have that feature, but somehow still use the term "ground", when there is no connection to the ground (earth), except for the rubber tires.

Very technically, it could be referred to as a "common collection point", but "ground" or "earth" is so much quicker and easier.

.

[salty_monk]

I always add one more between the frame & the battery. I make sure it's of similar gauge (or bigger) than the battery to engine & Shorter if possible. I then use it as a grounding post. On the Skunk I use the Airbox bracket as I don't have an airbox...

From there I ran one to the RR direct. I also run one to the plate the fuse box etc is mounted to. Seen too many old vehicles with bad ground paths (or earths as they would colloquially be called in England)
Here in Cali we don't have the weather to screw them up.