I have a LED voltage monitor that WAS attached to the parking bulb circuit so it would not constantly be drawing current. The bulb throws off the reading. I'm thinking of tapping it into the 2 leads that are on either side of the diode board. 1 is red (right side as looking at it) and the other side is black. Is it correct that these are upstream of the battery? I.e., they are the freshly made current from the charging system getting ready to go to the battery? Thanks.
This is known IMHO a bad idea: You do not have any fuse down there, and you will add yet another non-fused line with that construction. In addition, the other wire is the Y connector ... this would be 1 diode forward voltage (about 0.7 V) off from ground. PS: You have mail ...
Thanks Joerg. Will await your idea. End goal: Get accurate reading of system output without direct connection to battery. That would make me need a switch. I have a relay for the heated grips, but they're soldered, shrinkwrapped, etc and I don't want to disturb it. No, I don't plan to shell out the cash for an accessory board. If I can't just attach to some point on teh bike that's a good source without being always energized, I guess i'll buy another relay. What a pain.
Another tactic I thought about but never needed to act upon, for a low power consumption item like voltmeter, etc., maybe use a slow switching power transistor as a relay. More compact than a relay and IIRC cheaper (at Radio Shacks everywhere). According to coments I read somewhere from folks with more electronic/electrical knowledge than me, a big 20-30A relay doesn't perform as reliably at very low current draws as other type switching devices. That could all be just theory, but from what little education I've had regarding smoke and wires, it sounds reasonable. The issue was debated ad nauseum over on f650.com in relation to moving the voltage regulator's sensing wire (on the carbed models) from a point under the dash which was like in the OP affected by IR drops across lights & gauges & stuff. No clear cut winners in that debate, but it provided additional technical opinions. Edit: Strictly my personal preference, but I would always want to install a voltmeter right at the battery since that is where the balance between charging system and battery voltage decide which way the electrons will be moving at the battery. If a particular bike has a general relay close to the battery electrically like the Ducatis I've had, that would be close enough I think. Maybe. Depending on system influences (IR drops) at the relay.
Well, if I don't figure out something simple, I'll wire it straight to the battery and put a small waterproof switch in the line so it won't be constantly on.
I think he wants to say that he does not care about the voltage drop along the lines If you want an accurate reading on a 2V, you will need a relay (use that of your heated grips). There's no way - that I'm aware of - to bypass the voltage drop in the cabling that goes towards the headlight ...
Yes, I suppose mine is wired that way, relay-less. It is actually a direct connection of a voltmeter to the battery via a switched circuit (I found extra unused wiring along the harness)). And the gauge light is wired with the park light connections. Simpleton wiring, in other words. By wiring it this way, am I missing something apart from voltage drop across the harness?
What's wrong with the parking light connection. Isn't that on the other side of the ignition switch just like you want?
IMHO, the voltage drop that will be present after going from the big battery wire at the starter, then through the switch, will be un-noticeable on an analog voltmeter. Even with a digital voltmeter, you are talking tiny tiny voltage drops due to wiring alone. I would wire it to the switched side of the ignition switch, and go out and ride! That way, any gross drop will be seen, and unless you are working with highly sensitive electronics, just doesn;t matter on these airheads.............. Bob Peckham
The parking light is great for making sure it's only on when the bike is on. But my volt meter is one of the single LED type that is green, yellow or red, and blinks to tell you your volt range. There is juuuust enough drop from the parking bulb that it sits there and flickers green/yellow and drives me crazy. Otherwise, i'd just adjust for the drop mentally, knowing it was just the bulb. So, I'll try to figure out a way to do it right, or i'll just tap into my heated grip relay. Just don't want to do that because i'd have to cut wires or else posi-tap and sacrifice weatherproofing.
on my g/s, the meter is attached to the headlight I believe, but the headlight goes through an eastern beaver relay, so there is no voltage drop.
Hi, Just for the record, we are talking of something around 0.5 V, even more. At least that's what I measured on my R100TIC Apart from my nutpicking , I agree to the pragmatic approach: As long as one does not need ultimate precision, just connect it between some green (positive) and brown (negative) wires near the cockpit. And yes, I knew there was a reason why my approach does not use that third LED
I'm already thinking about the error of my ways. I'll have to make this one work (shipping from your place was killer!) or end up buying a Joerg special. Thanks all.
Indeed it was supposed to read "nitpicking", but now that you mention it ... @Datch: Just paint that "middle" LED black
