- Originally posted by Gorminrider View Post
There are a variety of reasons for not using the frame ground, the frame resistance might not be the best argument as resistance is also a function of cross sectional area and length.
And I will also agree it it is the connection points that are also the main issue, but in the end you have to have some conenctions points and the fewer the number the better. But it is "how and where" the currents flow that is as important to the discussion as connection points. In fact this is the basic problem with this thread there are so is so much anecdotal evidence being provided without a real understanding of the flows.
The SPG is the optimum configuration for the way the currents flow to minimize voltage drops between battery and R/R. That is to say it optimizes the charging system performance with respect to the Phase A tests at 5K RPM.
The SPG as described is not the only way to ground the bike, but it is the only one that "optimizes" the performance with the least amount of wire.
It optimizes that performance because (in the construction of the SPG as described) the only current flowing in the wire between the R/R(-) and the battery(-) is the charging currents to the battery.
Clearly other ways will work but they will not be as good in terms of minimizing those ground voltage drops. As described the SPG harness minimizes the ground points you have to worry about (Ed's notion that somehow all ground ring lugs have to be stacked in one spot is demonstrating he has no clue what the theory is behind this approach). Ands it keeps the currents separate so only the charging currents flow as described above.
In the beginning, there was the circuitous GS grounding problem nobody understood except to accept that their GS would burn starors at regular intervals.
Then before I ever arrived at the GSR, Baltzor discovered that if he added a wire between the battery and the R/R(-) he could generally improve charging performance.
In around 2009 I set it as my objective to do more and to really understand the charging system and what caused it to fail and what optimize it's performance. After developing a simplified model of the charging system, it because clear that while, the addition of the Baltzor's single wire improved charging, it was really only a partial solution because his wire would now collect all currents (14 amps at 5K RPM) between the battery and the R/R and not just the charging currents (4 amps at 5K RPM). What ever connections you have between battery and R/R if you have 3 times the current you have 3 times the voltage drop.
And so the notion of a SPG was born and with my development of the SSPB I started shipping what I call a SPG Harness. It is three wires combined into a single ring lug for the SPG and you stack a 4th B/W wire from the harness.
The three wires are
- R/R(-)
- Battery(-)
- Frame
All the wires are less than 1ft and this simple solution that optimizes performance has gotten more arguments simply because people have not put the effort to understanding the concepts. Clearly it is much more effort for some than others.
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