1982 GS650G Grounding

[Guest]

Hi,
I hate to bring this subject up again as I have read through all the posts I could get my eyes on and I still don't know exactly how to do this on my bike. I have the bikes rear half completely disassembled and decided to look at the wiring. Found that one of the stater legs that runs up to left handle bar as a dummy wire for the old headlight switch was melted at the bullet connection, so I took out the battery box and sandblasted and painted it and want to create a single point ground somewhere. My questions are if I make the SPB on the frame do I run a wire back to the - battery terminal? Or do I put the SPB on the mounting bolt for the RR and run a separate wire to the frame. Also the RR and the igniter are mounted to bottom of the airbox, I can't see how the igniter is grounded? The #8 engine ground that connects to the - battery has a pigtail on it that went to a rubber mount on the battery box and then went to the RR ground wire. This makes know sense to me. What should I do with this small wire from the - battery term and know matter which SPB I choose do run a wire back to wire to the battery?


I'm sorry I can't completely grasp this in my uneducated brain. Thanks for all your help M.K.

[Brendan W]

When the bike is running the current is supplied by the r/r and returns directly to the r//r, or tries to depending on the wiring. The stock earthing strategy relies on the frame as a return path. The problem with this is that there are potentially ( no pun intended) voltage drops at the frame connection points which is bad.
The SPG idea makes a single, low resistance collection point for return currents. Ideally it is as close as possible to the r/r and connected to it by a short wire. There is also a short wire to the battery negative. Some folks use one of the r/r mount screws as the SPG.
On my bike the SPG is one of the starter motor relay mount screws on the side of the battery box. It has the relay ground wire, the two black and white harness earth wires, the r/r ground and the wire to the battery negative. Quite a Christmas tree. But the r/r now has a clear view of the returning currents with minimal voltage drops. The battery negative has the starter motor return cable from the crankcase and the other end of the wire from the SPG only.
Most people now run the three generator output wires directly to the r/r with high quality connections.
You should find Posplayrs sig and get testing as soon as things are wired up. It would be a pity to toast a healthy stator because you didn't pick up on a failing r/r.

[Who Dat?]

As Brendan noted, the original configuration pretty much had the frame as the "single point ground". As long as ALL electrical connections are clean and tight, it should still work quite well, but time has a way of changing things. Posplayr seems to be the one who has done the most research on this topic and has some good testing points that are listed in his sig.

[60ratrod]

The ignitor has an in harness ground in its 4 pin connector, but that ground wire that bolts to the r/r-ignitor bracket is an additional frame ground, mostly for the r/r, but if you remove the ignitor from the bracket you'll see a heat sink on the back that should also get grounded through the frame ground as well. If you don't have that ground there, bad bad things happen, i found that out the hard way. What i did for my 650g's spg, is i connected all the grounds to one of the brackets under the seat by the fuse block, since i installed posplayr's sspb.

[mkles]

I was thinking of choosing that same spot for my SPB, should I run a wire from the RR bracket to that location, one from the battery box to that location and then a wire from SPB back to the neg. battery term?
Thanks M.K.

[posplayr]

I was thinking of choosing that same spot for my SPB, should I run a wire from the RR bracket to that location, one from the battery box to that location and then a wire from SPB back to the neg. battery term?
Thanks M.K.

I read most people's response and have little to add except a fine point. When you collect all the return currents (as Brendon described) with the final short path to the R/R(-) then it does not matter what you bolt the SPG to it could even be floating, mounted to plastic or mounted to the frame. The only point is that all the ring lugs are stacked and have a low resistance between them.That is why I supply the SSPB with a SPG harness where the common point is actually common to a single ring lug (crimped and soldered) for battery(-), Frame(-). and the R/R(-). The B/W ring lug is stacked on top and having a screw to keep them tight together with some dielectric grease will give a long maintenance cycle.

It is most important to keep the connections between battery to R/R clean, and with the SSPG the only currents running between the battery and the SPG is the battery charging current. This helps to keep the voltage drops low.

As long as the last run from SPG to R/R(-) is relatively short 14 AWG wire (less than 1 foot) it doesn't matter where the SPG is (as long as it is NOT the battery (-)).

Most people would need more than 1 foot of wire to go from the battery(-) to the r/r(-) so I don't recommend that. The battery (-) is not the lowest potential if you are charging at all. It is R/R(-).

[mkles]

Thanks so much for the responses and advise, any additional comments would be appreciated.

M.K.

[IanW]

Hi guys,
Hope this thread is still active...
I've nearly finished my GS650G rebuild out of various donor bits of pieces and I'm now busy with the wiring. I've had a good look through as many posts on earthing strategies and single point grounding as I could find, and they have been extremely useful. Amazing the knowledge and experience offered on this website! There is however two minor points that I'm a bit unclear on.
I've had to fabricate brackets for all the electrical components, and in doing so followed everyone's advice and made my spg at the starter solenoid, ran a cable from there to the battery etc etc as mentioned earlier in this thread.
My questions are: 1) because of my fabricated bracket, I'm not sure about the quality of the earth connection to the CASINGS for the R/R and the igniter. What exactly are the requirements for these earths, and should I, for instance, run an earth wire from the igniter mounting screw to the frame? and what is the function of the small L-shaped metal component which runs from the igniter case to near the cable terminals? Something to do with earthing?
2) Is it allowable to use the starter solenoid NEGATIVE POLE as the spg or must you use the bracket mounting point?

Thanks in advance,

Ian

[posplayr]

My questions are: 1) because of my fabricated bracket, I'm not sure about the quality of the earth connection to the CASINGS for the R/R and the igniter. What exactly are the requirements for these earths, and should I, for instance, run an earth wire from the igniter mounting screw to the frame? and what is the function of the small L-shaped metal component which runs from the igniter case to near the cable terminals? Something to do with earthing?

I think you might be getting a little confused about terminology. The SPG is simple. It returns all current to the R/R(-) while minimizing the currents running between the battery(-) and the SPG.

The only requirements are and as have been stated before are:
a.) SPG can be anywhere
b.) SPG should be located within 1 foot of the R/R(-). assuming you are using 14 Awg wire for this run. 16 awg for all grounds.
c.) Implicit in this is that all of the connections (between the battery and the R/R) are protected against corrosion and are low resistance (less than 0.01 ohms).

Realize you can only measure 0.01 ohms of resistance when there is 10 amps going through it and it turns int 0.1 volts.

If you have a factory ground wire for your ignitor you should clean it; it is however not nearly as important as the charging circuits. If you really want to run a ground run it to the SPG.

2) Is it allowable to use the starter solenoid NEGATIVE POLE as the spg or must you use the bracket mounting point?

I know I have said the SPG could be anywhere, but I did not mean at the positive side of the battery. If where ever you put the SPG causes a short then that is obviously not a good thing.

I should mention, I don't know what "negative pole" of the solenoid is.

[IanW]

Oh for goodness sake!!! It's finally penetrated my thick skull.
(I'm a mechanical engineer, nobody should ever let me near electricity).
For some reason, because one pole of the solenoid is connected to the + battery terminal, my mind decided without conscious input that the other pole would be negative. Of course it's not. Anyway, thank you, sending this query has prevented me making a serious and stupid error.

The ignitor grounding question was based on the following.

The ignitor has an in harness ground in its 4 pin connector, but that ground wire that bolts to the r/r-ignitor bracket is an additional frame ground, mostly for the r/r, but if you remove the ignitor from the bracket you'll see a heat sink on the back that should also get grounded through the frame ground as well. If you don't have that ground there, bad bad things happen, i found that out the hard way.

That is why I was a little concerned about the quality of the ground that I have.

Regards,

Ian

[posplayr]

Oh for goodness sake!!! It's finally penetrated my thick skull.
(I'm a mechanical engineer, nobody should ever let me near electricity).
For some reason, because one pole of the solenoid is connected to the + battery terminal, my mind decided without conscious input that the other pole would be negative. Of course it's not. Anyway, thank you, sending this query has prevented me making a serious and stupid error.

The ignitor grounding question was based on the following.



That is why I was a little concerned about the quality of the ground that I have.

Regards,

Ian

If your ignitor has a case that needs to be grounded, then probably anyone of these will work (harness B/W, frame or SPG). It is just not super critical compared to charging connections.

As mentioned SPG is to support the sensitive charging system connections that can degrade (e.g. corrosion) over time. If for example you hooked the R/R(-) to the negative side of the battery which is so popular, then all of the return current run from the battery negative terminal to the R/R(-).

If for example there is 0.05 ohms of resistance at the battery connections and all of the R/Rs 15 amps comes past then you will drop 15x0.05=0.75V volts lowering your batteries charging voltage by the same amount. If you construct the SPG (which you diligently maintain) then there is only 4 amps going from battery to SPG and that will only drop 4x0.05=0.2V!!

For the moment I'm ignoring the resistance of the wire as well which you can also overcome with a 10 awg wire but with the SPG 16 awg is perfectly fine.

So you could try to hook up yoru R/R direct to the battery using 10 AWG wires and connector pins that are designed for 16 awg or do the SPG and use more easily handled wire sizes. On the other hand the SPG concept seems to cause so much confusion, that perhaps the brute force approach is better??