Ground Loops

[supergrafx]

OK, after reading the 6 pages of comments, VERY CAREFULLY, I get that you make the r/r(-) go to the frame, and the -battery 8 guage wire to the engine casing. However, on page 3 or 4 (sorry, lost track), it was suggested to have the r/r(-) split, one way going to the frame, the other lead going to the -battery. By splitting the r/r(-) ground into two rather than daisy-chaining the r/r(-) from the frame and then to the negative battery clamp, is proper? Should I just hook Duanage's r/r ground to the frame or split the ground into two, one lead going to the frame and the other to the - battery terminal.?

 

[posplayr]

supergrafx

supergrafx

No really wanting to speak for Duanage, but he doesnt see mto think there are differences between grounding points.

As far as what to do with your bike and a Honda R/R you should only have to refer to picture Post #1. Of course you will have a sense wire to hook up which I did not show.

A simple point to point list for you:

1.) Three wires tied together at a mounting bolt for the R/R at the side plate
a.) R/R (-) from the Honda regulator to ring lug on a mounting bolt
b.) Battery (-) to a ring lug on the same mounting bolt
c.) Frame ground strap from bolt to frame (not the rubber mounted side plate)

2.) R/R (+) goes to the fuse box as normal

3.) Only connection other than 1b above to battery (-) is the 8 guage wire ground strap to the engine.

4.) connect your sense wire as suggested by Duanage

For the following discussion:

V_negative is measured from battery (-) to R/R (-)

V_battery is measured directly across the battery terminals

What you should notice if you omitt 1c above is the following:

The wire from the battery (-) to the R/R common ring lugs should carry 10 amps at idle and 12 amps at 3K RPM.

V_negative should drop and will likely be between 0.25-0.5V.

V_battery measured across the battery terminals should be something like 13.0V at idle and rise to 14.0V at 3K RPM.

After reconnecting 1c above you should notice the following:

The wire from the battery (-) to the R/R common ring lugs should carry 0 amps at idle and 2 amps at 3K RPM.


V_negative should drop by about 1/5 of what ever it was. If it was 0.5V it should be 0.1V.

V_battery should rise by what ever the change in V_negative is. So 13.0V will turn into 13.4V.

Hope this helps.

 

[duaneage]

Just hook it to the frame. Easy. Done. Simple.

 

[Suzuki_Don]

A simple point to point list for you:

1.) Three wires tied together at a mounting bolt for the R/R at the side plate
a.) R/R (-) from the Honda regulator to ring lug on a mounting bolt
b.) Battery (-) to a ring lug on the same mounting bolt
c.) Frame ground strap from bolt to frame (not the rubber mounted side plate)

What sideplate is this mentioned in point 1.) Where is it located?

What is the difference between earthing an item to the frame or the engine?

 

[bakalorz]

No really wanting to speak for Duanage, but he doesnt see mto think there are differences between grounding points.

As far as what to do with your bike and a Honda R/R you should only have to refer to picture Post #1. Of course you will have a sense wire to hook up which I did not show.

A simple point to point list for you:

1.) Three wires tied together at a mounting bolt for the R/R at the side plate
a.) R/R (-) from the Honda regulator to ring lug on a mounting bolt
b.) Battery (-) to a ring lug on the same mounting bolt
c.) Frame ground strap from bolt to frame (not the rubber mounted side plate)

2.) R/R (+) goes to the fuse box as normal

3.) Only connection other than 1b above to battery (-) is the 8 guage wire ground strap to the engine.

4.) connect your sense wire as suggested by Duanage

For the following discussion:

V_negative is measured from battery (-) to R/R (-)

V_battery is measured directly across the battery terminals

What you should notice if you omitt 1c above is the following:

The wire from the battery (-) to the R/R common ring lugs should carry 10 amps at idle and 12 amps at 3K RPM.

V_negative should drop and will likely be between 0.25-0.5V.

V_battery measured across the battery terminals should be something like 13.0V at idle and rise to 14.0V at 3K RPM.

After reconnecting 1c above you should notice the following:

The wire from the battery (-) to the R/R common ring lugs should carry 0 amps at idle and 2 amps at 3K RPM.


V_negative should drop by about 1/5 of what ever it was. If it was 0.5V it should be 0.1V.

V_battery should rise by what ever the change in V_negative is. So 13.0V will turn into 13.4V.

Hope this helps.

I was one of the people recommending using a wire from the regulator to the battery way long ago.

I still feel that that is an acceptable and even good way to wire it up.

The reasons are as follows:

When I got my bike, the original R/R ground wire went to the battery box, after going through the battery box there was another wire from the battery box to a frame ground.
All the screws into all these mechanical grounds were corroded.

I could have tried to clean that up, but felt that going through the battery box was a joke.
So I wanted to bypass that, and the easiest way is a wire directly from the R/R ground directly to the battery.

Even before you did your analysis, I was aware of the fact the the return currents will go through this wire, and produce a drop.
However, I didn't have any real issue with it.

The problem with your analysis is that you are using ridiculously inflated resistances in the path from the R/R to the battery.

When the ground wires were recomended, it was typically suggested to use 12 guage. The only connector needed is the ring terminal at the battery, so there are no drops in connectors. Assuming 2 feet of wire thats a resistance of only .0031 ohms, FAR FAR less than you were using in your examples. (and my wire is more than 1 foot, but much less than 2, so even less in reality) With a 10 amp difference in current, thats an additional drop of .03 volts (the number you call V_negative) ... Big freakin hairy deal ... if 3/100 of a volt matters to whether your battery charges or not, you have other serious charging issues.

Even if you were to use 16 gauge wire like the OEM harness then the drop only rises to .08 volts (assuming 2 feet of wire, in reality it would be probably be shorter, and less voltage drop)
This is a bit more noticable, but even using the inadequate OEM wire guage, not that bad.

Additionally your suggestion of using 2 wires from the R/R: one to the bat, and one to frame ground, will be pretty much OBE on any bike that is not hopelessly corroded to death ... the path you label as the sneak path is probably going to be much lower resistance than the wires themselves.

You've really just created a solution in search of a problem, cause the problem you think you've identified is pretty much just not a problem.

In conclusion: There were three ways of grounding the R/R

1) The OEM way by tying the R/R to the frame. The load currents are mainly not shared with the battery charging currents except for the short section of wire from the R/R to the frame. My only issue with this method is that it can be hard to get rid of all the corrosion (and thus resistance)
(its also extra wires to undo if you are removing the battery box (at least on my bike))

2) Run a wire from the R/R neg directly to the battery neg. (use 12 guage) Accept that you will lose about 0.02 volts, (Oh the horror !!)
I put it in my sig a long time ago ... it works fine ...

3) Do Pos's thing shown in post 1. Connect the R/R to both the frame and directly to the battery. Its not much extra work, so what the hell, why not.
Bask in the realization that you are getting a theoretical 0.02 extra volts (minus whatever you lose due to the fact the sneak path shown in fig 1 exists ... cutting into that 0.02 volts)

Summary All three methods of grounding the R/R will work fine.
If you have a significant voltage drop from the R/R to the battery
(What Pos calls V_negative) your problem is corrosion or bad connectors, but not implicit in the method you chose to ground the battery.
Lets not make mountains out of molehills people

P.S. I still have the same sig ...
I see no reason to change it.

 

[rustybronco]

I could have tried to clean that up, but felt that going through the battery box was a joke.
So I wanted to bypass that, and the easiest way is a wire directly from the R/R ground directly to the battery.

If I may a small suggestion... don't connect anything to the battery other than the two battery cables. "properly" hook any additional grounds to the end of the cable where it attaches to the engine. also any extra (+) connections should be connected to where that cable attaches the the starter solenoid. or at least tie strap the "extra" wire to the battery cable if you do.

my reasoning being, when someone removes the battery for the winter or just to change it, any additional "eyelets" can fall down and be missed. I have had it happened to me, and it may happen to the next owner (as was me).

FWIW...

 

[posplayr]

I was one of the people recommending using a wire from the regulator to the battery way long ago.

I still feel that that is an acceptable and even good way to wire it up.

The reasons are as follows:

When I got my bike, the original R/R ground wire went to the battery box, after going through the battery box there was another wire from the battery box to a frame ground.
All the screws into all these mechanical grounds were corroded.

I could have tried to clean that up, but felt that going through the battery box was a joke.
So I wanted to bypass that, and the easiest way is a wire directly from the R/R ground directly to the battery.

Even before you did your analysis, I was aware of the fact the the return currents will go through this wire, and produce a drop.
However, I didn't have any real issue with it. .

OK great

The problem with your analysis is that you are using ridiculously inflated resistances in the path from the R/R to the battery.

When the ground wires were recomended, it was typically suggested to use 12 guage. The only connector needed is the ring terminal at the battery, so there are no drops in connectors..

Wait a minute didn't U just say

All the screws into all these mechanical grounds were corroded.
..

Oh yea thats right it's the connection that get corroded not the wire that has excessive resistance.

OK right I'll ignore the rest of this

Assuming 2 feet of wire thats a resistance of only .0031 ohms, FAR FAR less than you were using in your examples. (and my wire is more than 1 foot, but much less than 2, so even less in reality) With a 10 amp difference in current, thats an additional drop of .03 volts (the number you call V_negative) ... Big freakin hairy deal ... if 3/100 of a volt matters to whether your battery charges or not, you have other serious charging issues.

Even if you were to use 16 gauge wire like the OEM harness then the drop only rises to .08 volts (assuming 2 feet of wire, in reality it would be probably be shorter, and less voltage drop)
This is a bit more noticable, but even using the inadequate OEM wire guage, not that bad.

..

OK so we are back on point

Additionally your suggestion of using 2 wires from the R/R: one to the bat, and one to frame ground, will be pretty much OBE on any bike that is not hopelessly corroded to death ... the path you label as the sneak path is probably going to be much lower resistance than the wires themselves.

..

Well I guess you missed the current sharing calculations. And on BTW most of the GS have corrosion problems even with significant attendance.

You've really just created a solution in search of a problem, cause the problem you think you've identified is pretty much just not a problem.
..

Well I guess this is an eloquent statement of supposition :-#.

In conclusion: There were three ways of grounding the R/R

1) The OEM way by tying the R/R to the frame. The load currents are mainly not shared with the battery charging currents except for the short section of wire from the R/R to the frame. My only issue with this method is that it can be hard to get rid of all the corrosion (and thus resistance)
(its also extra wires to undo if you are removing the battery box (at least on my bike))

..

Since you are again having those pesky issues with corrosion, might I suggest dielectric grease as this is the most important ground for the R/R if not the system.

2) Run a wire from the R/R neg directly to the battery neg. (use 12 guage) Accept that you will lose about 0.02 volts, (Oh the horror !!)
I put it in my sig a long time ago ... it works fine ...

..

Thanks for your contribution

3) Do Pos's thing shown in post 1. Connect the R/R to both the frame and directly to the battery. Its not much extra work, so what the hell, why not.
..

Gee thanks for finally agreeing

Bask in the realization that you are getting a theoretical 0.02 extra volts (minus whatever you lose due to the fact the sneak path shown in fig 1 exists ... cutting into that 0.02 volts)
..

Whoops remember all your calculations for resistance assume a total lack of oxygen and therefore any oxide byproducts; oh crap I should just say corrosion.

Summary All three methods of grounding the R/R will work fine.
If you have a significant voltage drop from the R/R to the battery
(What Pos calls V_negative) your problem is corrosion or bad connectors, but not implicit in the method you chose to ground the battery.
Lets not make mountains out of molehills people

P.S. I still have the same sig ...
I see no reason to change it.

Thanks for your contribution. It sounds like you agree that none of this matters when operating in a vacuum (i.e. no corrosion in orther words in outer space), but when it exists the problem is it exists...... Did I say that?

Oh that's right the whole premise of this thread was to figure out what power and grounding scheme was least susceptible to corrosion caused connection resistance. Grounding the R/R(-) to the frame and providing the single lead from battery (-) to R/R (-) is best. :dancing:

Pos

 

[posplayr]

Suzuki Don

Suzuki Don

What sideplate is this mentioned in point 1.) Where is it located? ?

The side plate is the thing where your fuse box, R/R and starter relay normally mount. Because it is mounted in rubber it is not a frame ground unless jumper ed to the frame.

What is the difference between earthing an item to the frame or the engine?

This is difficult to answer in a technically correct way (simply) without making some assumption to limit the scope.

What I can say is that there is a separation of currents in the Suzuki design that has most load returns through the frame (lights, coils, etc ). Those currents have to get to the R/R (-) and therefore Suzuki provided for a R/R (-) frame ground. We should not forget about this and make sure it remains in tact.

In addition, because of the above, coupled with the simple R/R design (i.e. no voltage sense like the Honda R/R has 1/2 of ), the R/R regulation has a poor reference (i.e. it is not tied to the negative side of the battery). So a direct connection between the R/R and the battery is warranted to improve charging, but at the same time we don't want to upset the normal ground returns.

So given this context, the ground returns described essentially separate the load current returns from the battery charging current returns. Because the returns are separated, the voltage errors are minimized at the battery. Doing anything else will raise those voltage errors and reduce the charging voltages at the battery.

Hope that helped explain.

Pos

 

[Suzuki_Don]

The side plate is the thing where your fuse box, R/R and starter relay normally mount. Because it is mounted in rubber it is not a frame ground unless jumper ed to the frame.



This is difficult to answer in a technically correct way (simply) without making some assumption to limit the scope.

What I can say is that there is a separation of currents in the Suzuki design that has most load returns through the frame (lights, coils, etc ). Those currents have to get to the R/R (-) and therefore Suzuki provided for a R/R (-) frame ground. We should not forget about this and make sure it remains in tact.

In addition, because of the above, coupled with the simple R/R design (i.e. no voltage sense like the Honda R/R has 1/2 of ), the R/R regulation has a poor reference (i.e. it is not tied to the negative side of the battery). So a direct connection between the R/R and the battery is warranted to improve charging, but at the same time we don't want to upset the normal ground returns.

So given this context, the ground returns described essentially separate the load current returns from the battery charging current returns. Because the returns are separated, the voltage errors are minimized at the battery. Doing anything else will raise those voltage errors and reduce the charging voltages at the battery.

Hope that helped explain.

Pos

Thanks Jim,

Some of us just need a practical "HOW TO ", we will never fully understand the theory, so it's good to have experts like yourself that can help us to understand it. Personally I still cannot understand why there is a difference in the engine and frame earth when they are both connected to each other. my limited reasoning would say it would not matter which one the earths were connected to as they both eventually lead back to the "-" side of the battery. But I am guided by you and accept what you say.

I have looked at my '77 wiring diagram and have noted the difference in earthing techniques (which ones go to the frame and which ones go to the engine). When I put my bike back together (the frame has just been powder coated) I will have to clean up the earthing points (file away the powder coat) to get good connections. And then attach the earths as shown in the diagram (frame or engine).

 

[posplayr]

Suzuki_Don

Suzuki_Don

Thanks Jim,

Some of us just need a practical "HOW TO ", we will never fully understand the theory, so it's good to have experts like yourself that can help us to understand it. ).

Appreciate your comments. My first posts on this was to ellicit comments v.z. do a "How to". Once the approach is vetted then a simple "How To" can be completed.

Personally I still cannot understand why there is a difference in the engine and frame earth when they are both connected to each other. my limited reasoning would say it would not matter which one the earths were connected to as they both eventually lead back to the "-" side of the battery. But I am guided by you and accept what you say.
).

As Matchless reminded me , power and grounding can be a complex subject. As a general rule it is best to keep power returns simple and an approach called "single point ground" tends to do that. Single point ground means that all current returns are run separate back to a single point. This avoids current sharing and some devices having bouncing grounds due to current flows in other loads. I'm digressing but this "new/old" grounding strategy tries to embody that concept.

Next it must be made clear that currents flow from the source of power(the highest voltage in the system) through the loads and returns back to the low side of the source. For the GS there are actually TWO SOURCES; the battery and the stator. When the engine is off the battery is the highest voltage and all currents that flow to loads (starter motor, solenoid) return back to the low side of that source which is the negative terminal of the battery.

On the other hand, when the GS is running, even if the battery is discharging, the stator is producing the dominate amount of power that goes to lights, coils and igniter. This current DOES NOT RETURN TO THE BATTERY it has to RETURN TO THE STATOR. That path is from the R/R (-) through the lower legs of the internal diode bridge.

See the figure below from a GS1100 manual shows the current path I'm describing. The current from the stator goes through the upper leg of the diodes in the R/R bridge , goes through the load (in this case both to charge the battery and power the GS loads) the return currents are shown returning to the R/R (-) via the frame ground to get back to the stator. This happens whether the R/R is regulating or not. When the R/R regulates, it simply pulls "some" of the current going to the load and directs it back to the stator.

This is important to understand otherwise not much else will make sense.

So if you review your schematics in the manual, you will see that there really is no primary current path from the lights back to the negative side of the battery(unless you assume Frame ground and engine ground are the same). Most all of the loads active when the GS is running return through the harness to ring lug that goes to the frame. Most GS R/R are shown with a frame ground on the R/R (-) and this is where the current comes back into the R/R to get back to the stator.

Hopefully all that is clear because now we will discuss the only modification that has become popular, namely adding a direct wire between R/R (-) and the negative side of the battery. Everything discussed above is the bone stock configuration.

In the drawing below you can see how the battery and starter system are configured. When the engine is off the only power available if the battery, when the solenoid is energized, the starter motor see the battery voltage and battery current flow through the motor to the engine ground and come back out the #8 ground strap back to the negative post of the battery. Other things are powered like the coils. Coils are grounded to the frame. The only way for current to get back to the negative side of the battery is through the engine mounting bolts attaching the engine to the frame. I called this a sneak path partially at least because it is not an explicit element in the schematic. It is simply understood.

Next is the stator loops which are as I described above, current flows from the stator to the R/R(+) out to the fuse box, through the loads, and then returns back to the R/R (-) (NOT THE BATTERY) by either a frame ground path of a direct wired path to what amounts to a single point ground at the R/R (-). So depending upon if the GS is running the source is either the stator with current coming to R/R (-) or there is battery power alone and current returns back to the negative side of the battery.

So now comes the issue of adding this extra wire between R/R (-) and the Batt (-) post. This is not part of the Suzuki schematic or even an undocumented part of the original design (at least not that I have seen).

So first we have the stock case with no ground wire. How does the battery charge from the stator output? well the 2 amps of assumed charging current has to sneak to the engine, got to the motor mounts, go through the frame and then get to the R/R (-). This is an indirect path.

The indirect path is bad because that two amps of current will likely cause a voltage drop somewhere between the battery (-) and the frame/motor mounts. In addition because all of the normal load current (the 10 amps in this example) plus the 2 amps of changing current are coming into the frame grounded R/R (-) any resistance there will cause lower voltages at the battery in proportion to how much current is flowing through those respective connections. Remember it was this frame ground corrosion that prompted bakalorz to change his grounds. So in this situation when there is degradation of the contacts, there will be chronic under charging of the battery. The biggest issue is likely the 12 amps trying to go from the frame to the R/R (-).

Now we introduce the ground wire for the second case. What happens now? Well we have now provided a direct path for the charging current to return to the R/R (-). In addition the voltage drop between the R/R (-) and the Battery (-) is only associated with the lower 2 amps of charging current rather than the 12 amps of total current. So in theory we can reduce this voltage error by about 1/6 or the ratio of 2 amps:12 amps.

Well in reality there is that little short piece of wire into the R/R (-) as well as the common connection shown at the R/R mounting bolt that all share the full 12 amps. Assuming any losses there can be kept to a minimum we can approach this 1/6 voltage loss improvement. So if when you measure your voltage from R/R(-) to Battery (-) and it would read 0.5V, it should now be below 0.1 volt.

In this case we are also realizing a benefit f the "single point ground" philosophy as the battery (-) is not sharing load current and therefore the sensing of battery voltage by the R/R is improved.

For completeness, we should explore what happens if the R/R (-) frame ground is removed but the ground strap from R/R (-) to Battery (-) is left in place. Well the stator is still the largest source when the GS is running and we already know that current must flow back to the R.R (-) to get to the stator so who does it do that? Well all of our loads are frame grounded, so those currents have to "sneak" back through the frame/motor mounts through the #8 battery strap to the negative side of the battery and then up the ground strap to the R/R (-). What is wrong with this? Well we have a similar situation where there are 12 amps flowing through a single wire and connections from battery to R/R (-). Any resistance times the 12 amps will cause larger voltage drops and lower regulation voltage than case 2 above that only flows 2 amps from Battery (-) to the R/R (-).

This has all been a little long, but I hope clear enough to explain the differences between the three cases.

Case 1: Stock Susuki frame grounded R/R (-) with no EXTRA R/R (-) to battery (-) wire. You end up with 12 amps of shared current coming through the frame to the R/R (-).

Case 2: Stock Suzuki frame grounded R/R (-) but With THE EXTRA grounding strap. Now you have the return currents separated so only 2 amps flows from the battery to the R/R (-) keep the R/R regulation tighter

Case 3: is Where the R/R (-) frame ground is removed and the EXTRA STRAP is the only thing to carry return currents to the R/R (-). This is pretty similar to case 1 but the current flows through the frame engine in the opposite direction.

I have looked at my '77 wiring diagram and have noted the difference in earthing techniques (which ones go to the frame and which ones go to the engine). When I put my bike back together (the frame has just been powder coated) I will have to clean up the earthing points (file away the powder coat) to get good connections. And then attach the earths as shown in the diagram (frame or engine).

Agreed, but I might add that the schematics are not exactly how Susuki built the GS. Just from looking at my GS1100E and GS750E harnesses, the Frame ground is really only one ring lug that is tied near the battery box. All of the side plate mounted "pseudo frame grounds" actually have a jumper from the harness as near the same point to the side plate. As it turns out (I won't bore you with the details), it doesn't matter much where they attach to the frame the separation of load and charging currents happens if you follow the schematic as i outlined at the R/R (-) mounting bolt.

Good Luck and hope this explanation has helped.

Pos (Jim)

 

[Guest]

This is an excellent discussion! #70 is especially good. The interplay between engineering analysis and keep-it-simple practical experience is quite useful. I've never made the effort to understand what is going on with the R/R and stator and the grounding concerns. This thread will help me considerably. Pretty soon I'll get one of Duangage's Honda R/Rs, and then I'll delve into this before installation. I know that cleaning all of the connectors and measuring resistance will be a necessary job.

Thanks.

 

[Suzuki_Don]

Yes I agree Post #70 is fantastic. POS I am still trying to get my head around all of these posts, but #70 explains a lot of things to me that I did not realise before.

As I've just had my frame, engine mounts, headlight, the ears that hold the headlight, battery box, etc. powder coated. Can you give me a brief rundown on the parts and locations that will have to have the powder coat removed to allow the "-" loop to work properly with the frame, engine and battery.

Also is the aluminium finned exterior of the R/R "-", in other words the "-" wire coming from the R/R goes to the frame, right. Does the other wire need to go from the R/R mounting bolt to the battery"-".

 

[bakalorz]

Rats, the forum has a line limit, so this has to be in 2 parts ...

Appreciate your comments. My first posts on this was to ellicit comments v.z. do a "How to". Once the approach is vetted then a simple "How To" can be completed.

As Matchless reminded me , power and grounding can be a complex subject. As a general rule it is best to keep power returns simple and an approach called "single point ground" tends to do that. Single point ground means that all current returns are run separate back to a single point. This avoids current sharing and some devices having bouncing grounds due to current flows in other loads. I'm digressing but this "new/old" grounding strategy tries to embody that concept.

Next it must be made clear that currents flow from the source of power(the highest voltage in the system) through the loads and returns back to the low side of the source. For the GS there are actually TWO SOURCES; the battery and the stator. When the engine is off the battery is the highest voltage and all currents that flow to loads (starter motor, solenoid) return back to the low side of that source which is the negative terminal of the battery.

On the other hand, when the GS is running, even if the battery is discharging, the stator is producing the dominate amount of power that goes to lights, coils and igniter. This current DOES NOT RETURN TO THE BATTERY it has to RETURN TO THE STATOR. That path is from the R/R (-) through the lower legs of the internal diode bridge.

See the figure below from a GS1100 manual shows the current path I'm describing. The current from the stator goes through the upper leg of the diodes in the R/R bridge , goes through the load (in this case both to charge the battery and power the GS loads) the return currents are shown returning to the R/R (-) via the frame ground to get back to the stator. This happens whether the R/R is regulating or not. When the R/R regulates, it simply pulls "some" of the current going to the load and directs it back to the stator.

This is important to understand otherwise not much else will make sense.

So if you review your schematics in the manual, you will see that there really is no primary current path from the lights back to the negative side of the battery(unless you assume Frame ground and engine ground are the same). Most all of the loads active when the GS is running return through the harness to ring lug that goes to the frame. Most GS R/R are shown with a frame ground on the R/R (-) and this is where the current comes back into the R/R to get back to the stator.

Hopefully all that is clear because now we will discuss the only modification that has become popular, namely adding a direct wire between R/R (-) and the negative side of the battery. Everything discussed above is the bone stock configuration.

In the drawing below you can see how the battery and starter system are configured. When the engine is off the only power available if the battery, when the solenoid is energized, the starter motor see the battery voltage and battery current flow through the motor to the engine ground and come back out the #8 ground strap back to the negative post of the battery. Other things are powered like the coils. Coils are grounded to the frame. The only way for current to get back to the negative side of the battery is through the engine mounting bolts attaching the engine to the frame. I called this a sneak path partially at least because it is not an explicit element in the schematic. It is simply understood.

And this is one REALLY BIG issue I have with your analysis.

You call this a sneak path and handwave it away as insignificant.

But nothing could be further from the truth.
The frame is a FAT piece of metal, so is the engine; their impedances are quite low. They are connected using BIG bolts drawing BIG machined surfaces together tightend to high torques. Connecting the engine to the battery is a short piece of 8 guage wire that has over 6 times as much conductive area as any other wire on the bike.

AND YOU IGNORE IT ?!?!?!

WTF Posplayer, its a HUGE factor !!!

If your analysis is to have ANY meaning whatsoever you absolutely must account for this NUMERICALLY IN YOUR CALCULATIONS

Oh sure, when you need it to explain how currents get somewhere you mention it in some but not all cases ... but you don't have a term for that current shown on your drawing, and it doesn't show up in your calculations.

You don't even attempt to quantify it's impedance compared to the impedance of the various wires.

Of course doing all that is hard, because you need to quantify a bunch of things you have no data on. But its absolutely essential for your analysis to be valid

I don't want to be rude, but until you account for that, all your analysis isn't worth a bucket of warm spit.

Show that analysis without a frame/engine ground analysis to anyone actually involved in electrical design and they would tell you fix it and not come back untill you correct it.

Really

It just doesn't represent what is happening on the bike until its in there.

It is that bad an error.

In my first post I mentioned it, and in your reply you just blew it off with:

Well I guess you missed the current sharing calculations. And on BTW most of the GS have corrosion problems even with significant attendance.
​

Well, yes I did miss the current sharing calculations, please point them out to me. (The ones that actually include a term for the "sneak path")

And if you have enough corrosion on all the motor mounts that THAT significantly increases the impedance of this path, I would suggest you not ride your bike anymore. Because that much corrosion means the next time you hit a bump your engine will fall off the frame.

Next is the stator loops which are as I described above, current flows from the stator to the R/R(+) out to the fuse box, through the loads, and then returns back to the R/R (-) (NOT THE BATTERY) by either a frame ground path of a direct wired path to what amounts to a single point ground at the R/R (-). So depending upon if the GS is running the source is either the stator with current coming to R/R (-) or there is battery power alone and current returns back to the negative side of the battery.

So now comes the issue of adding this extra wire between R/R (-) and the Batt (-) post. This is not part of the Suzuki schematic or even an undocumented part of the original design (at least not that I have seen).

So first we have the stock case with no ground wire. How does the battery charge from the stator output? well the 2 amps of assumed charging current has to sneak to the engine, got to the motor mounts, go through the frame and then get to the R/R (-). This is an indirect path.

The indirect path is bad because that two amps of current will likely cause a voltage drop somewhere between the battery (-) and the frame/motor mounts. In addition because all of the normal load current (the 10 amps in this example) plus the 2 amps of changing current are coming into the frame grounded R/R (-) any resistance there will cause lower voltages at the battery in proportion to how much current is flowing through those respective connections. Remember it was this frame ground corrosion that prompted bakalorz to change his grounds.

(continued in part 2)

 

[bakalorz]

Part 2

So first we have the stock case with no ground wire. How does the battery charge from the stator output? well the 2 amps of assumed charging current has to sneak to the engine, got to the motor mounts, go through the frame and then get to the R/R (-). This is an indirect path.

The indirect path is bad because that two amps of current will likely cause a voltage drop somewhere between the battery (-) and the frame/motor mounts. In addition because all of the normal load current (the 10 amps in this example) plus the 2 amps of changing current are coming into the frame grounded R/R (-) any resistance there will cause lower voltages at the battery in proportion to how much current is flowing through those respective connections. Remember it was this frame ground corrosion that prompted bakalorz to change his grounds.

Ummm, kind of but not quite ...
I was really unhappy with the R/R ground going through the battery-box.
(in other posts it seems to be refered to as the "floating flat plate")
Those two connections had a lot of corrosion, and were needless besides
(and to make it even worse, had to be dis and re-connected anytime I needed to get behind the battery box)
A freaking retarded design if I ever saw one.
Thats what I wanted to get rid of.

When I tore it all apart, I cleaned the actual frame ground since other stuff was connected there too.
I didn't have any real aversion to grounding the R/R there.
However, since I had to extend the R/R ground wire anyway (to bypass the battery box cr@p) I decided what the heck, might as well go to the battery so as to make sure its got a good connection to the R/R.
And that worked well.
Other posters tried it an said it worked for them. And thats how it grew.
Many previous posters in other threads have indicated it eliminated their charging problems.

For troubleshooting, I think its easier to have them do that then trying to explain how to measure the difference between R/R ground and Battery Ground.
Using the commonly suggested 12 guage wire, that gets the Voltage drop to 0.02 volts. BIG WHOOP DE DOO

You've either said or implied a voltage drop of 25 times that much (0.5 v) for this case using made up resistances in your sharing analysis. That is pure and unadulterated Bullsh!t.
In my previous post I called you on it and in your reply you pretended you could justify ignoring the real drop and using your pretend numbers based on corrosion of connectors giving higher resistance.

But what connectors ...
At the R/R end, solder or splice using butt connectors. Either of which when properly done is not particularly subject to corrosion (as opposed to quick disconnects, which can be, but even those can be protected with dielectric grease)
At the battery end its a ring terminal. A lot of contact area, tightened down by a big old bolt. If the ring terminals at your battery are so neglected as to be significantly corroded, then you won't be able to start your bike, since the much higher starting current will cause voltage drops an order of magnitude higher than the charging currents.

So in this situation when there is degradation of the contacts, there will be chronic under charging of the battery. The biggest issue is likely the 12 amps trying to go from the frame to the R/R (-).

Now we introduce the ground wire for the second case. What happens now? Well we have now provided a direct path for the charging current to return to the R/R (-). In addition the voltage drop between the R/R (-) and the Battery (-) is only associated with the lower 2 amps of charging current rather than the 12 amps of total current. So in theory we can reduce this voltage error by about 1/6 or the ratio of 2 amps:12 amps.

Well in reality there is that little short piece of wire into the R/R (-) as well as the common connection shown at the R/R mounting bolt that all share the full 12 amps. Assuming any losses there can be kept to a minimum we can approach this 1/6 voltage loss improvement. So if when you measure your voltage from R/R(-) to Battery (-) and it would read 0.5V, it should now be below 0.1 volt.

Or you could clean the corrosion off and restore the drop to less than 0.1 volts that way.

Or you could do it the way I have suggested for years and get a .02 volt drop

Or you could do it your way (which I suspect could get you to .0033 volts FWIW)

In this case we are also realizing a benefit f the "single point ground" philosophy as the battery (-) is not sharing load current and therefore the sensing of battery voltage by the R/R is improved.

The "sneak path" kills the single point ground.

For completeness, we should explore what happens if the R/R (-) frame ground is removed but the ground strap from R/R (-) to Battery (-) is left in place. Well the stator is still the largest source when the GS is running and we already know that current must flow back to the R.R (-) to get to the stator so who does it do that? Well all of our loads are frame grounded, so those currents have to "sneak" back through the frame/motor mounts through the #8 battery strap to the negative side of the battery and then up the ground strap to the R/R (-). What is wrong with this? Well we have a similar situation where there are 12 amps flowing through a single wire and connections from battery to R/R (-). Any resistance times the 12 amps will cause larger voltage drops and lower regulation voltage than case 2 above that only flows 2 amps from Battery (-) to the R/R (-).

Yep, you're right ... by 0.02 volts worse. Don't you dare pretend its any more than that.

This has all been a little long, but I hope clear enough to explain the differences between the three cases.

Case 1: Stock Susuki frame grounded R/R (-) with no EXTRA R/R (-) to battery (-) wire. You end up with 12 amps of shared current coming through the frame to the R/R (-).

However please note that this is not a huge problem. This scheme can work quite well as long as you do just enough preventative maintenance to prevent the frame grounds from corroding.

Case 2: Stock Suzuki frame grounded R/R (-) but With THE EXTRA grounding strap. Now you have the return currents separated so only 2 amps flows from the battery to the R/R (-) keep the R/R regulation tighter

Yep, by 0.02 volts better than case 3

Case 3: is Where the R/R (-) frame ground is removed and the EXTRA STRAP is the only thing to carry return currents to the R/R (-). This is pretty similar to case 1 but the current flows through the frame engine in the opposite direction.

In a very simplistic analysis yes, but there is more to it than that in a detailed analysis.

[/quote]


Sigh ... I really didn't want to get into it again with you PosPlayr, but a couple of things ...

You say that your grounding scheme is better than the one I have been advocating, but for all practical purposes its not.
Aside from getting me defensive, you are causing people who have already implemented that method to now make needless changes
(for example BassCliff seems to be doing just that)


An un-nuanced reading of your analysis implies that your way will do 0.4 volts better than a stock system.
This is also not true, your method may do .4 volts better than a corroded OEM system, but not significantly better than one which has had any corrosion cleaned.
Again, causing people who have properly functioning OEM systems to make needless "improvements" to their bike.


Also, you made a big deal in your prior reply to me about how corrosion is such a big deal with our bikes. Well, they are 30 years old and often ignored by prior owners; so yeah, sure.
But no matter which grounding system you use; OEM, mine, yours ... if there is significant corrosion, something on the bike won't work right.
And if you do the maintenance and keep it clean, all three methods (OEM, mine, yours) will result in a properly running bike.
...
For a bike with some (but not horrible) corrosion, both your method and mine will delay it affecting the battery for a bit (and equally well, don't trot out the canard of "shared current" using a made up resistance to try to say there's a real difference) but in the end, you still have to clean the corrosion.
which gets us right back to "if you do the maintenance and keep it clean, all three methods (OEM, mine, yours) will result in a properly running bike."


For all the lurkers ... Sorry this got so long, and the tone got as adversarial, but IMHO, letting a faulty analysis, supported by made up numbers be represented as correct just provides bad info to people...

For all the lurkers having charging troubles: clean any corroded connections down to bare metal, make your connections, protect the connections with paint, vaseline, or dielectric grease as appropriate, occaisionally verify they are still uncorroded. Use the OEM path, My Sig suggestion, or Posplayr's method; in the end it REALLY doesn't matter as long as you are thorough and methodical about it. ... and thats the real scoop.

Sigh ... good luck with your bikes.

Martin