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MGA Volt Meter Installation MGA

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Ray7Smith

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What gauge wire should I use to connect the volt meter to the generator? Which terminal on the generator is the wire from the meter connected? How can I use my multimeter to check for voltage output of the generator?

Thanks,
Ray
 
Hi Ray, the wire gauge isn't terribly important for a voltmeter, as the current will be very low, unlike an ammeter. I believe the battery voltage is what you really want to keep track of though, so connecting it to the battery terminal or the generator battery lead (the heavy one that goes from the generator to the battery) is what you want.
 
Snap, I goofed. Don't run the voltmeter to the battery lead. The current to the voltmeter is low, but not that low. You don't want it to be showing voltage all the time. I'd find out where the battery voltage is switched by the ignition (hint, find out where the ballast resistor of the coil goes to), and connect it there, so that the voltmeter turns off with the ignition. My bad.
 
Ray - If you are looking to install a voltmeter in your car, connect the positive terminal (assuming a negative ground car)to the white wire coming off the ignition switch and the negative wire to ground (reverse these connections if the car is positive ground). As Sparkydave above states the wire gauge is not an issue with a volt meter as the current is quite low, but I would use 18 or 16 gauge wire for ease of working with.
Cheers,
 
This may not be a significant issue, but I installed a relay on my motorcyle's volt meter in order to prevent voltage drop from the battery to the meter, and thus an incorrect reading on the volt meter.

Voltage drop will definitely affect the reading on the meter, but again, this probably isn't a significant issue with automotive electrics because your alternator output is greater than a bike's.

I connected a 12 ga. wire directly to the battery terminal with a fused wire, then wired the relay with a lead to a switched circuit. This way, no voltage drop and a very accurate reading. Also, it's safer to use a fused wire to/from the meter.

Has anyone else done it this way in a car? With my motorcycle (weak alternator-low output), I have to monitor voltage with great accuracy so as not to discharge the batt when using accessories (heated clothing, etc.)

Just wondering . . .
 
A voltmeter takes very little current; it's on the order of milliamps. Even if you had an ohm of resistance in the connecting wire, a few millivolts difference isn't even going to register on an analog voltmeter. A relay isn't going to make a bit of difference, unless you're powering a high current device like a headlight.
 
I seem to love overkill, Dave!

I'm using a digital voltmeter, too. Since I wired directly to the batt, I'm glad I used a fuse and relay.

Oh well, it WAS fun installing it! /bcforum/images/%%GRAEMLIN_URL%%/wall.gif
 
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