how do i wire a voltometer to a car

I have a 1986 cadillac sedan deville and I want to add two voltometers to my car so I can monitor the voltage will driving I want to add one to the battery and the altertnator. So the pos lead is the pos leads do I use the batts and alts ground leads or I use the chasis. Also I kno you fuse the pos lead put ill will be using a small guage wire like 12/14 so what amperage of a fuse would I use. Also any suggestions

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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"

If memory serves me right.. I think you would connect an amp meter to the alternator. The Volt meter can be connected to the battery +/- terminals.. or you can connect it to any 12v power wire and ground in your car. Just make sure it is a switched ignition 12v so the meter does not stay on continously. A good choice would be your cig lighter +/- wires. Mine is connected where my amp connections are.

So your main concern for you putting one in your car is to montior your amps activity . I mainly want to moniter the cars charging system. If I was to put on my amps(I have 3) do I put it on the amps main power wire or what location did you use

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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"

Actually I use the volt meter (Stinger) to monitor my car battery output. I have it connected into the main amp power wire at the distribuition block that goes to 2 amps. It honestly doesn;t matter where you place the volt meter. I measured the current at my car battery with a standard volt meter and got the same exact current reading as the other meter near my amps. You can honestly tap your volt meter into any switched ignition power supply or accesory wire. Your best bet would be to wire tap your cig lighter wires for power and ground since that is a switched ignition power source. If you want to connect it directly on the battery.. just extended the wires through your firewall and connect them and the meter to a spdt switch.. that way you can turn on the meter when you want..and off when not needed. But the current draw from a volt meter is so low.. it would take days to drain your battery. The ideal reading when the car is running is 13.8 volts, and 11.8-12.2 resting. Hope this helps.

So your saying it doesn't matter where you put it on the battery source. Is it pointless to put one on the alternator, the reason for me wanting one on is is to detect a dieing alt.

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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"

There are many laws scientifically written regarding current and voltage etc.. one of them applies to this. But for the most part.. you will generally get a consistent reading on any 12volt wire in your car. Generally if an alternator is going to die.. it happens quick or it just quits. The only way to detect your alternator is going out or dying is if your volt meter has low readings will the car is running. Example.. less than 12volts.. and higher voltages exceeding 14volts are common in an alternator with a problem. This is my experience.