308 voltmeter? Anybody ever installed one?

Measure your clock opening, that'll give you the gauge mounting hole size.
Believe Summit's catalog gives mounting holes for at least some of their gauges. The hole sizes are pretty standardized so if you find it for one gauge size, others of that size should take the same hole.

For a console installation, you can hook the gauge to the cigarette lighter power lead & ground. When the lighter isn't being used, you'll be reading the battery's voltage. The cig. lighter wiring is fairly heavy duty. Just make sure the cig. lighter fusebox contacts are clean.

 

If you want a digital gauge, get one from Radio Shack that plugs into the lighter. You can take it out later if you want. It also has an inside/outside temperature display as a bonus. You can mount it anywhere with velcro or double sided tape.

 

I did this many years ago to my 77 308. I found a veglia voltmeter that looked right & installed it where the clock was. I no longer have the car & I dont remember where I sourced the voltmeter.

 

I have seen one installed in the little space in the far lower left side of the dash,next to the door. It looked great there,and you can keep the Clock in where it is. And,IMO,is easier to glance at than where the Clock is. Will be doing that myself one of these days....

 

The volt meter presents very little load on the circuit and can be hooked to any circuit in the vicinity that has a +12 V wire that shuts off when the ignition shuts off (so you don't drain the battery with the key off due to the meter). Just don't hook it to a circuit with a large load on it that will tend to drop the voltage across the fusebox (i.e. the rear window defroster, lights, etc. You will get a false low reading.) There is probably a nice +12 V line going to the oil temp guage right next to the clock that will work fine. (Don't use the +12 v to the clock, because it stays on when the key goes off).

Birdman

 

Did this as a part of my VDO gauge swap this past winter - check the archives for a post that I made on this if interested in the details. And yes, the 1980 does have the unique front to back console mounting of these gauges. Anyways, it's a direct replacement for the old clock, and well worth doing in my view.
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I installed a voltmeter, and it was great. I used a VDO l"Vision" series ighted voltmeter from eGauges.com, priced very reasonably at $26.44 (no affiliation), http://www.egauges.com/vdo_mult.asp?Type=Voltmeter-12&Series=Vision&Cart=.

It was a great little unit, easy to install, and very helpful. I bought it after my alternator failed. It's also lighted, which is nice. Further, it doesn't clash with the classic 308 or even updated 328 veglia displays (was not able to find a Veglia voltmeter - and making a custom one would be awesome but expensive [but doable, I think, by professionals]).

I had it mounted below the twin AC ducts. Previous Owner of the 308 had a nice, black metal frame of the correct width with two round cutouts of the correct diameter (2 and 1/8 if I recall?). I can't find these anymore, though. They were cleanly installed with rivets up into the twin AC duct bottom cover plastic. Previous owner used these for twin Exhaust Gas Temperature gauges when he tracked the car (the old 308 I'm referring to). An ammeter would be a nice complement to it, but after several attempts I couldn't make the wiring happen.

I am now considering mounting the same gauge in the 328, a bit more cleanly--perhaps to one side of the coin pocket to the left of the steering column.

--Mike

 

You want switched ignition voltage (switched +12V) for the actual voltmeter. You'll also need a ground (local, clean metal should be fine). You'll need a different ground for the light (according to the instructions). Finally, for the +12V for the light, you'll want to tap into a dimmer-switch controlled "dimmable" hot lead connected to one of the other dimmer-switch controlled gauges.

There are a number of places to find switched voltage--you'll need that new radioshack Voltmeter that I told you about to test for this. On 308 fuseboxes, it's easy to find--just run a fused lead from one of the exposed spade connectors on the fusebox that have +12V when the ignition switch is "on" but nothing when off.

--Mike

 

1985 308GTS, cig is always on.

 

By the way, I am now considering using a relay to control the voltage to the voltmeter (non lighting circuit) part of the VDO voltmeter gauge.

(I'm redoing the install on the 328, it's slick!)

The idea is that the voltage indicated by the switched voltage from the ignition or whatever is not really accurate of that of the battery--I've noticed, say, a 1 volt difference on some switched voltage circuits from what the battery would read.

An easy option is to use a new relay I have laying around, and use the ignition lead as the signal which will allow current from the battery (or some other [fused!] close-to-battery circuit) to flow through to the voltmeter.

Outside of circuit complexity, can anyone think of any disadvantages to doing this?

--Mike

 

Being able to switch the voltmeter to measure several points is a reasonable thing to do, just a bit of a wiring job. I'd use a multi-position rotary switch to select several points that I wanted to monitor, not a relay. BTW, be sure each wire has a fuse in line with the point your'e monitoring, or in line with the wire in case of a short circuit.

Had forgotten that the cigarette lighter is always on, so maybe not the best idea if you car is sitting a long time. I'd use that point because I always pull the battery disconnect when my car is going to sit more than a couple of weeks.

 

Verell,

Great points about the voltmeter. Rotary / multi-select switch is definitely a good idea... Wonder if Radio Shack has anything that might work... The big question is where to mount it... I don't really have any way to make it look "nice".

I was thinking in the car today, if I did do the relay (still an option), I would:

1. Have the +12V being measured drawn from the current socket;
2. Have the nearby switched ignition wire be the signal to that realy;
3. Use a nearby ground as the ground for the relay.

I wonder if there is any voltage drop between input voltage to a relay and the resultant output voltage when activated?

 

I was surprised when I got the car a few years back that it didn't have a volt gage. This is the 1st car in 40 years that I have had without a full set of gages. But after upgrading the alt. to 85A and putting in a new battery I don't get paranoid over the "G" light. I posted back on an earlier thread about this and once you understand how this system works you don'y worry about it. I purchased a plug in type volt meter and use it once in a while to check battery condition. So my 2c is to just drive it and don't worry about it. My car sits all winter in a unheated but above freezing garage and it starts without any problems when I crank it up for spring. Never disconnect the batt or use fuel stab. Works great.

 

Greg,

When you do the voltmeter install, I don't recommend messing with any of your existing gauges... Perhaps as stated above the clock if you must, but consider this picture as another option. The previous owner of my old 308 had Exhaust Gas Temperature gauges installed nicely in a double-gauge bracket, riveted to the bottom cover of the A/C ducts. I swapped one of the gauges out for a voltmeter.

So, this might be an option to consider.
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YEP , forget it and just drive. I bet everyone has the same symptom. So let your mind be free.

 

It should be less than couple of milli-volts (ie: ~ 0.002 V). Your voltmeter won't be able to measure the difference. Don't worry about it.

 

FYI, this is an opinion that I don't concur with.

Tell you what - when your "G" light is glowing with your car running [once the alternator has kicked in - exceed 2500 rpm once], grab your voltmeter and stick the positive lead up into the trouble light socket and the negative lead to some local ground. Check the voltage. If you get good voltage (> 12.5V say, looking for around 13). If you get 13 and the light's glowing, you probably have nothing to worry about (although the light should not be glowing).

--Mike

 

Also,perhaps a tad O.T....I installed an Optima Battery in my 308. Great. Never have to worry about using the Air Conditioner at Night with the Lights and Stereo on.... Though,the Stereo isn't on that often...