In cab voltmeter - accessories or not?

[Guido]

Hey guys, just wondering if anyone is able to help me out here...

I'm soon to collect a very basic mini fluro blue digital voltmeter to hook up to my aux battery and will probably look to get a second one for my main battery. Is it possible to hook this up via my accessories (key)?? This voltmeter has a very simple pos and neg wire. Do you see it as a good thing to do or just keep it running 24/7??

Cheers
Guido

 

[Old.Tony]

I'd do it via accessories, just to make sure it doesn't drain anything while you're not there. After all, if you aren't there, there's no need to display the info!

 

[KraftyPg]

I'm going to do something similar soon, I've got a 12v ciggie connector coming into the cab from my aux battery so instead of running another cable back to the battery for the meter I'm just going to connect the meter to the back of the ciggie socket.

If I wanted one from the main batt I'd use the same theory, although for anything with a LED etc I'd put in an inline switch because I don't need to show everyone outside the car that I have another light inside the cabin.

 

[amber.2]

Ive just bought one of these i'm hoping it will fit into where there is a blank near the instrument panel it should fit with out too much trouble .
http://www.ebay.com.au/itm/161081575565?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

 

[Guido]

Cool... I think I purchased the wrong voltmeter. Mine only has pos and neg (2wires). I assume the third is the accessories connection wire???

Lucky it was only $2.15!!!

 

[Old.Tony]

Two wires is all that's needed. Black to vehicle chassis, red to something that comes active when accessories are on and you've got what you need.

 

[KraftyPg]

Pfft, there is no such thing as a wrong voltmeter if it comes in around $2.

The current draw of the above linked meter is <60ma and most will be similar, theoretically it could drain a battery but it would take a long time. Even running it full time off the main battery it wouldn't be an issue except the light it would produce in a dark cabin.

There are other digital meters on the market that are about 10mm high draw less than 5ma and under $4 if your that worried about current draw.

 

[Guido]

Sweeeet. You guys are unreal! Thanks heaps!

So next question...I have a battery in the tub linked by an isolator under bonnet. Is it possible to connect a volt meter from the aux battery side of the isolator to volt meter in cab and only have it on with accessories???

 

[KraftyPg]

Yep

 

[Guido]

Would I need a 3 wire volt meter to do the above?

 

[Old.Tony]

Yes. Use a standard single-pole relay.

Bring TWO wires in from the auxiliary battery (connect a small 2A fuse to the battery, then connect the long cable to the fuse). Connect the black wire to the black wire on the voltmeter.

Now, connect the relay like this. Pin 85 to any wire that's live when accessories are on. Pin 86 to the vehicle chassis. Pin 30 to the red wire coming from the auxiliary battery and pin 87 to the voltmeter.

When accessories come on, the relay is energised and connects the aux battery to the voltmeter. Couldn't be easier! Just be aware that there'll be a small amount of voltage drop over the length of cable. Calculate it and mentally add it.

 

[amber.2]

I think I will just connect mine to the rear of the cigarette lighter socket, that way it will be on accessory's.

 

[happy john]

Here is my setup mate works a treat used as heavy wire as possible straight to both batteries.
John

 

[stockstandard]

have a look at the first post in this thred http://www.navara.asia/showthread.php?t=13617

It looks like a double pole switch that allows you to view both batteries on the one LCD. So if you wanted to don't need to get 2 LCD units.

 

[Lever]

I bought one of these.

http://www.ebay.com.au/itm/LCD-Ciga...=AU_Car_Parts_Accessories&hash=item4ab7c5fa9a

Have had one in each car for a few years now and found to be reasonable accurate.

 

[KraftyPg]

Geez the ingrish on that ad is brilliant. Lucky it's such a self explanatory item and people buying it probably don't need an accurate description.