where to measure voltage from?

[ncc74656]

im going to buy a voltage gauge tomorrow and wounder, should i hook it to the batteries or to the sub amp power connections?

was looking at this guy: http://www.autozone.com/autozone/accessories/Auto-Meter-2-1-16-in-8-to-19-Volt-black-face-LED-display-Cobalt-digital-voltmeter-gauge-includes-4-ft-tubing-or-wiring-harness/_/N-25l7?itemIdentifier=703726_0_0_

[Wicks]

You'll have different voltages at various locations in your vehicle.

A voltmeter will measure voltage only where it's connected.

Therefore you'll want to connect it wherever you want to monitor the voltage specifically.

Usually the most sensitive location to monitor is the voltage into your largest amplifier(s).

So you'd want the voltmeter connected directly to the amplifier's power terminals.

[kl0wn]

Agree with Wicks. It all depends on where you want to read the voltage at. I personally have mine on my sub amp

[ncc74656]

sub amp it is. my speaker amp is 1/3 the power of my sub amp so i think that makes sense.

[Wicks]

Also keep in mind that these simple 2-wire voltmeters draw power for the meter through the same wire they measure with.

Therefore they aren't quite as accurate as 3 or 4 wire systems.

Plus if they are connected to your power source directly they may be turned on all the time and drain battery power.

You may want a switch on it to keep that from happening.

[kl0wn]

If you want, you can buy 2 separate meters. Have 1 on your sub amp, and the other one on your highs amp.

When measuring the voltage between my 2 amps with my actual DMM, I only noticed a slight difference between the two amplifiers, around .1-.2 so I just keep that in the back of my head when watching my meter.

[Wicks]

Switches can be left on and still be an issue.

So you could switch it on with your key ACC wire.

Also many people use relays on thier remote turn-on wires.

When the HU turns on, it activates the relay which turns on the amps and voltmeters.....and fans and LEDs and whatever other accessories you want.

[TheMonolith2001]

Is that REALLY an issue? I would think this volt meter would have to be left on for probably months before it drained your batteries any significant amount. I leave a phone charger plugged in all the time that has some blue LEDs on it and I can't imagine this volt meter is drawing all that much more. Someone else can do the math if they want. The stinger volt meter which is probably pretty similar to this draws about .2 amps.

[Guest]

Is that REALLY an issue? I would think this volt meter would have to be left on for probably months before it drained your batteries any significant amount. I leave a phone charger plugged in all the time that has some blue LEDs on it and I can't imagine this volt meter is drawing all that much more. Someone else can do the math if they want. The stinger volt meter which is probably pretty similar to this draws about .2 amps.

the stinger meter has a turn on lead. so its off when the stereo (or whatever you attach the turn on lead to) is off.

i dont think anybody here would want a parasitic load draining their battery all the time, shortening the batterys life.

[Wicks]

Is that REALLY an issue? I would think this volt meter would have to be left on for probably months before it drained your batteries any significant amount. I leave a phone charger plugged in all the time that has some blue LEDs on it and I can't imagine this volt meter is drawing all that much more. Someone else can do the math if they want. The stinger volt meter which is probably pretty similar to this draws about .2 amps.

I have no idea what the current draw on this specific meter is so I don't know its overall parasitic affect.

I always like to inform an OP about any possible drawbacks when I answer a question, regardless of whether its a critical situation.

Its better to fully understand a device and how it works then to cut corners and take chances.

Sure, you maybe could get away with leaving it overnight, but that would greatly depend on many factors:

-Current draw of the device.

-Size of your battery(s).

-How often you start the car to run the alternator, how long you drive the vehicle to fully charge the battery(s).

-Whether it would be OK to leave for a weekend or in a non-daily driver?

A simple $10 relay avoids all these issues.

Plus, at least me personally, I'd rather not have a bright numerical display lit up in my dash all night long.