Where to hook up voltmeter to check regulator voltage?

Hey guys,

Just purchased a small voltmeter I plan on installing either on the inner fairing panels or at the instrument cluster on my '86 VFR750F to make sure the reg/rec isn't attempting to fry anything precious.

DigitalMeter.com - Digital Voltmeters manufactured by DATEL

Where would be the best place to tie in the leads to check the output voltage of the R/R? Right downstream of the R/R?
I didn't check the schematic yet to see which wires feed the battery yet since I just ordered it.

Any help is greatly appreciated,

Ryan

 

I soldered leads on my voltmeter and hooked it to the battery.

The battery or ignition wiring (there should be directions with your voltmeter).

I have mine wired to a switch since it is wired to the battery or I should say the leads are anyway. I just turn the switch on when I want to see the volt readings.

If you wnat more info PM me. I'm busy at work and can't post pics.

BZ

 

He, that was the advice I gave to someone else on the SOHC forum, guys there recommended hooking it up to the ignition switch wires in the headlight bucket for an old CB750.

I might wind up doing that in the end with the switch, I'll see what other responses this fleshes out.

 

Across the terminals at the battery.....cuz there could be voltage drops along various circuits.

 

Sqirrel nailed it. I was reluctant to reply, but the wiring is such an issue that I would suggest wire to the battery but only if you checked the voltage drop from r/r to the battery.The drop is most likely gonna shock you.

 

Sounds like what I'll want to do, throw a SPST switch directly to the battery in there when I get it and call it good.

Thanks guys,

Ryan

 

Sorry if this is stating the obvious, but be sure to use a fuse located as close as possible to the positive terminal. It will create a very slight voltage drop, but the alternative is a lot worse.

 

TO the battery and I would use a fuse and a relay unless you want your battery dead.

And the indash option is the best:

 

That setup looks nice.

 

Fuse is always a good idea, but the relay might not be needed. Find the current draw of the meter, and compare it to the amp-hours of your battery. Any decent high impedance meter should not draw much.

Or just check the voltage drop between the battery + and the downstream side of the key switch. Maybe you don't care if it is just a couple tenths of a volt. Then when the switch is off, no current draw.

Final solution is to parallel a heavy wire from battery to switch so there WON'T be much of a voltage drop (other than what is in the switch contacts).

 

I suggest you read this before taking any further considerations:

Wiring a Relay for Accessories

 

I think he is planning to use an on/off switch, and not use a relay. Although a relay makes a lot of sense for other additions. The only reason I haven't added one for the electric vest is that I know within about 2 feet of walking away whether or not I've left it plugged in. :biggrin:

 

Hey Guys

Just take into the fuse box,with someother like oil pressure light (it is in my vf700F).Then you don´t need fuse or relay.And it starts when you igniotion switch is on.

Best regards

Gunnar

 

Just for information's sake, I'd like to post here: I just wired a Datel VM into my Gen 5 and the easiest place I found close by was to untape the harness at the front left area in front of the instrument cluster. I soldered (and heatshrink) into the Brn/blu wire for keyed power from the blue cluster plug and the dark grn wire from the grey cluster plug. This will cover the Voltmeter with the [Position meter tail, Ind & illum] lights fuse. Somewhere I read that someone wired it into a front running light. The problem with that is the running light (and the voltmeter) gets turned off when the signal light is activated. Not a big deal but not as good as it should be. Voltage drop in the harness, while important, isn't really relavent here. This meter is for comparitive purposes; you are taking note of what voltage the bike has when it's normal and then monitoring it if the voltage drops or more likley when it rises too high (fire). If you need heated vests etc I like the idea of the blue seas fuse block under the seat but I'd try to find one that uses the smaller fuses; more compact and then the bike uses only one kind of fuse. I also think wiring a relay into the licence plate light circuit to feed this fuse block from the battery is the right way to do it. This would be the more professional way to go and it's really not that hard or expensive. The recurring issues with all bikes is heat created by loose connections, this means keep the crimps and connections tight and only solder things as a sealant for corrosion. Soldering as a means of achieving a mechanical connection on high amp circuits like additional fuse panels or starter/ battery cables is a no-no because if the connection gets hot as they do, the solder melts and the connection falls apart. low amp circuits are fine to solder but big wires need a mechanical connection swadged tight. Hope this helps!

 

I'm pretty open to what will work best, switch or relay or just tapping into a circuit that only turns on with the ignition.

I wasn't sure if there was an accepted, sure-fire place to tie into on my model of bike to see if the rectifier is trying to fry the battery and harness.

 

I think the best place to start is with your wiring schematic. Find the key switch and work backwards until you find a suitable place on the drawing that's covered by an appropriate fuse. If you could get me a copy of your drawing I would be happy to offer a suggestion. I would also need the wire color code legend as well. I personally don't know your model well enough to give you the easy answer. My post was really for when someone does a search for information. Your post seemed the best place to put it. I'm happy to help if I can! I really like where SLOVFR put his.

 

Alright, finally got it in the mail last night and I got bored so I decided to look at the '86 750 schematic in the back of the manual and do a quick setup to get some numbers.
It appeared that the Yellow/Black wire coming off the ignition and fusebox (labeled Parking in the schematic, I assume these are the running lights?) was as good as any place to tap for the positive, decided to hook up the negative to the frame right side by the cowl stay.

Well, hooked it up and it starts reading in the 11 volt range when I rev it, and when I let it go to idle it goes up to around 12 volts, odd.
Decided to grab my multimeter and put the probes on the battery recharge adapter that hooks into the battery tender, only the reading is a whole volt higher on average- 12 volt range.

Is this volt loss the loss I am seeing from the running lights (If that is what the Parking circuit is?), it sounds like I will probably want to tap the circuit behind the fusebox and ignition elsewhere.
The instructions for installation are absolute rubbish,

(We suggest connecting a wire from the positive
terminal of the meter to an accessory position on your ignition switch and
connect a wire from the negative terminal to the frame of the motorcycle.)

yeah, total crap.

Any suggestions?

 

Well, from what Squamish said this tap might be as good as any other, I would just be looking for something way off normal, be it high or low.

I'll probably tap some other ignition spots tomorrow when I get some time.

 

The Volt difference could be the local frame ground, try hooking the ground up to the battery and see if the Volt reading is better. Using the chassis as a ground is no longer recommended, that was a twenty years ago thing and thoughts on chassis grounds have changed . If I could see the schematic myself it would be easier, but really it's just a matter of finding what wire off the back of the key switch is power on when key on noteing it's color and finding a convienient place to tap into it. In my case the wire passes through a(number of) suitable fuse(s) and changed color and I found an easy spot to unwrap the harness do the work and tape it up again; Looks factory and the fuse selection makes the most sense by description if one needs to work on it later rather than a friggin' in-line fuse hidden away. If you test the voltage at the battery and the voltage is inverted as the bike revs I'd say the charging system is not working, the higher the revs the more juice the system needs that the charging system is not providing. Check the stator continuity (ohms) and/or it is possible to measure the AC output voltage between each of the three legs (usually yellow wires) if that checks out then it's time for a Reg/Rec. Feel the regulator; is it warm? It shouldn't be cold and it shouldn't be HOT.

 

I'll try and scan a copy of the schematic, that seems to be the only way to piece it out to post on here.
Yeah, I didn't investigate too much just hooked it up where it looked decent schematically and gave her a go- one of my neighbors dropped by and insisted I drink a few beers with them- couldn't say no to that
The voltage did increase to 13 and some change if I remember correctly on the multimeter hook up when I revved, I just thought it would increase a little more than that- didn't take enough time to run through the RPM's and record my readings- would have had to hook up my MAC tach for that. I'll do some more investigating when I get some time- I need to get my rebuilt CB swingarm back together before I start overhauling this beast.

I think I will have to tap directly to the battery for the negative, won't hurt to give it a whirl and see what happens.