B
bakalorz
Guest
My understanding is that most R/R?s are five wire these days. I bought a 2004 CBR600 R/R and that was the case. Not trying to be disagreeable, but if the ?sense? wire circuit design was superior, why did Honda go away from it?"Easier" - probably.
"Better" - I doubt it. If you have a 6-wire r/r available, it will charge at a lower engine speed and provide better regulation because it reads what is downstream of the ignition key and has a better idea what it is putting out than just monitoring its own output wire.
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The better charging at lower engine speed part is totally incorrect; the rest of it ... well, its complicated ...
A R/R with a sense wire will have absolutely no advantage at low RPM. At low RPM, the limiting factor will be the output of the stator, not what the regulator does. (in fact, the regulator does nothing at all at low rpm (although the recifier still does its thing ...))
What the sense lead (or leads, there can be one for ground too) CAN do is provide the refrence voltage to the regulator on wires that are not being dragged up or down in voltage depending on the changing electrical load (and the changing I*R voltage drops that occur in the wiring as the loads change)
So the effect of that is that the charging voltage does not change when the loads change (if you turn the lights off, or turn on some power hungry auxilary load for example)
However, there is a catch to this ... the sense lead(s) make the regulator try to hold the voltage "wherever the sense lead is connected" at the setpoint. If you connect the sense lead right to the battery(using a fuse), it will hold the voltage at the battery constant.
This will be good.
If you connect the sense lead into the harness somewhere, it will adjust the R/R output to hold that point in the harness at the setpoint, and the battery voltage will vary depending on the I*R voltage losses in the wiring between that point in the harness and the battery.
This is not as good, and is what we are trying to avoid.
So the closer to the battery you can connect the sense leads, the better.
So, what point in our wiring harness is closest to the battery ... turns out (at least in a 650 GL) that right where the R/R is tied in is really close.
Any place that is switched by the ignition switch is farther, so you get worse regulation using the sense leads than if you sense at the R/R.
So the use of sense leads on our bikes is counterproductive unless we connect them to the battery with leads that don't share any current with the loads.
So we would want to connect directly to the positve battery terminal using a dedicated wire and a fuse ... except a lot of the units using sense leads want them to be switched, because they draw a good bit of parasitic current when the bike is not running, and will run down the battery if constantly connected.
Our bikes do not provide a dedicated switched line to the battery. But you could connect directly to the positve battery terminal using a relay switching a dedicated wire (with a fuse). If you go to that much trouble, then a R/R using sense leads can provide slightly better results than a 5 wire regulator. If you tie into the wiring harness somewhere else, you will get worse regulation than with a 5 wire R/R
Any bike that used a R/R with sense leads from the OEM would be likely to have run a dedicated switched line to near the battery.
So the short answer is:
Unless you go to a LOT of extra trouble, a R/R with sense leads will give you worse results than a R/R without sense leads
BTW, one thing you CAN (and should) do with any of the regulators is to run a heavy (14 guage or bigger) ground wire DIRECTLY from the negative output of the R/R to the battery ground. This essentially does the same thing for the ground that using a sense lead does for the positive.