volt meter hook up question

[speedracer]

OK this time I'm going to ask before I screw something up!  I'm hooking up a gauge pod, I got the oil and temp but the volt meter, theres where I'm stumped.  Is it possible to run a new wire directly to the battery or the one wire altanator or how do I do this?
When I start messin around with wiring I'm famous for burning a whole wiring harness if not the car!  HELP!!!!!
Thx, johnny

[donsrods]

You want the voltmeter to be hot when the key is in the "on" position.  Just find a terminal on the ignition switch that is hot only when the key is turned on, run a wire from there to the + side of the voltmeter, then run another black wire (preferably) from the - side of the voltmeter to a good, known ground. That's it.

Voltmeters just give you a reasonable idea of how many volts are sitting in your battery at all times, when the key is on.

I think you are confusing this with an ammeter, that reads the charge and discharge out of the alternator.

If you don't have one, buy one of the $ 5.00 and up test lights that look like an icepick with a black lead coming out of the top, and usually an alligator clip on the very end of that wire. They are invaluable for finding 12 volt sources, and are easier to use than a multimeter, because you don't have to keep looking at the face of it.

JMO,

Don


PS:  The oil and temp gauges should have been wired the same way, because you want them to only work when the key is "on". The only difference is that those 2 gauges have 1 more stud that goes to the appropriate sender.

It is starting to get warm over here in Ft. Myers already for the year. How is it in Melbourne???

[enjenjo]

A voltmeter just need power when the key is on to work, there isn't much laod, an 18 ga  wire is big enough. You can even hook it to gauge power.

[speedracer]

You want the voltmeter to be hot when the key is in the "on" position.  Just find a terminal on the ignition switch that is hot only when the key is turned on, run a wire from there to the + side of the voltmeter, then run another black wire (preferably) from the - side of the voltmeter to a good, known ground. That's it.

Voltmeters just give you a reasonable idea of how many volts are sitting in your battery at all times, when the key is on.

I think you are confusing this with an ammeter, that reads the charge and discharge out of the alternator.

If you don't have one, buy one of the $ 5.00 and up test lights that look like an icepick with a black lead coming out of the top, and usually an alligator clip on the very end of that wire. They are invaluable for finding 12 volt sources, and are easier to use than a multimeter, because you don't have to keep looking at the face of it.

JMO,

Don


PS:  The oil and temp gauges should have been wired the same way, because you want them to only work when the key is "on". The only difference is that those 2 gauges have 1 more stud that goes to the appropriate sender.

It is starting to get warm over here in Ft. Myers already for the year. How is it in Melbourne???

Thanks Don
Yea the weather today is alittle cool maybe 70 or so.  I don't know what I was thinkin, but glad I ask before I torn out the wiring harness!!

[speedracer]

A voltmeter just need power when the key is on to work, there isn't much laod, an 18 ga  wire is big enough. You can even hook it to gauge power.

Hey thanks for the info, guess I had a brain fart!  johnny

[donsrods]

You should see some of the questions I ask. You absolutely did the smart thing in checking before you did something potentially expensive. Wiring is nothing to mess around with.

One of the reasons you see voltmeters now instead of the old ammeters is because they are safer. With an ammeter you had lots of current flowing to and from the gauge, and they sometimes shorted out or the wires did, and then it was smoke and fire time. Voltmeters use just a small amount of current.

Yeah, I actually ventured outside today to go buy some Nyquill and some Kleenex (picked up a cold somewhere this week) and it is sort of cool here too. But we noticed that it is starting to pick up temperature wise, especially when we are trying to work in our shop. Last summer we fried in there, even with a big fan coming in the door and two pulling it back out the other side.

Hey, since you are on the other coast of Fla. do you know anything about Advanced Paint Stripping service in Largo?  I think my Son and I will be trailering our bodies over there to have them media blasted, as there is nobody here who does that.

Also, is there anyone who does louvering there?

Ft Myers is totally void of these kinds of businesses.


Thanks,


Don

[speedracer]

You should see some of the questions I ask. You absolutely did the smart thing in checking before you did something potentially expensive. Wiring is nothing to mess around with.

One of the reasons you see voltmeters now instead of the old ammeters is because they are safer. With an ammeter you had lots of current flowing to and from the gauge, and they sometimes shorted out or the wires did, and then it was smoke and fire time. Voltmeters use just a small amount of current.

Yeah, I actually ventured outside today to go buy some Nyquill and some Kleenex (picked up a cold somewhere this week) and it is sort of cool here too. But we noticed that it is starting to pick up temperature wise, especially when we are trying to work in our shop. Last summer we fried in there, even with a big fan coming in the door and two pulling it back out the other side.

Hey, since you are on the other coast of Fla. do you know anything about Advanced Paint Stripping service in Largo?  I think my Son and I will be trailering our bodies over there to have them media blasted, as there is nobody here who does that.

Also, is there anyone who does louvering there?

Ft Myers is totally void of these kinds of businesses.


Thanks,


Don

Don I live in Melbourne on the east coast, we're not near Largo, thats around St Pete somewhere.  But theres a place here in Melbourne called Charlies Customs 321-727-7117 they may do what your wanting to do, when it comes to hot rodding thats where everyone goes!!  atleast around this area.  Yea I'm really new into rodding so most definitly will be asking questions, like that MSD box I hope they send good instructions-----------thanks johnny
ps if you ever get over this way let me know OK!

[donsrods]

Yeah, what was I thinking. This cold has me all screwed up, or maybe it's the 3 doses of Nyquill.    

Now I see why the hippies used to drink Robitusin like it was going out of style.

Thanks for the tips, though.


Don

[reborn55]

You guys may not agree--but I always hook mine directly to the battery.  I like to see what the battery is getting and the state of charge it is.  I have all the ambulances that I service hooked up this way.  Just feel more comfortable this way.

[donsrods]

So what do you do about shutting it off so you don't have it drawing all the time?  


Don

[reborn55]

Used to use a battery disconnect on the rigs, but had to get away from that because of memory in computers.  Have never had a problem running a battery down that I know of--course they get a lot of use.  In my 55 I may not drive it for 2-3 months at a time and it it has always done me well--even with a 7 year old Delco battery.  In the seminars I go to they always preach the importance of a fully charged battery, so they recommend reading voltage at the battery so when it is loaded you actually see what the alternator is putting into the battery and how it will take it.    A lot of people will disagree but I like the concept

[donsrods]

Nah, if it works for you, it works for you.  I've just never seen it done this way in any car or boat application, they always go through the ignition switch first.  I just don't know if you would get any significant voltage difference by doing it either way.  Plus, at their best, these are $ 30 - $ 50 instruments, and aren't 100% accurate anyways, they just give you a general reading of the voltage.

I called a well known instrument manufacturer one time because a customer had installed 2 new tachs, and one was different than the other by about 500 rpms. When he switched them to the other engine they were still off by 500. The man at the factory said to me "buddy, what do you want, they are $ 100 dollar instruments, what kind of accuracy do you expect?" And you know what, he was right. Day in and day out we see instruments that are way off the mark, and totally different than 6 other ones in the box.

I guess in your ambulance application you need to know how much you have available, and like you said, they don't sit long enough to drain the batteries. In a car that sits for weeks or months at a time I think it would be a problem. (we even disconnect the memory circuit on the stereos of the boats we service, as they will drain a battery in a couple of weeks)


JMO,


Don

[reborn55]

Never had a problem(like I said that I know of) using a voltmeter.  Even in my streetrod with the battery switch--I have it wired for memory to work in stereo and clock and never failed me yet and it sets from November to March.  Interesting--will have to check the draw one of these days for my own curiousity.

[wvcab]

just a thought. what if you installed a relay in the line between the battery and the guage, and controlled the relay with the key in the run position.

this way you can see the volts at the battery, but only with the key in the run postion.

[reborn55]

that would work.