I'm not really set on using a voltmeter. I've been having a minor problem throwing the alternator belt (actually just flipping it over) and my Vintage Air controls are driving me nuts. They say it has to do with low voltage at start up or something so I thought a volt meter might show what's going on.
I think I'll try to find the wiring instructions for my after market gauges and see what it takes to wire up the ammeter. Especially since you say it's not that dangerous.
You might want to think some more about using the volt meter.
Here's my thinking:
1. The wires should already be in place if the other console gauges are already wired.
2. A voltmeter can show what the voltage is to where if it's low, you can see that and if it's high, then it reads that.
3. Installing a volt gauge with other console gauges already in place should take a LOT less time than properly adding in an ammeter gauge. In other words, how much is your time worth. I like easy requiring less time.
4. If the wiring is not in place out to the engine bay you can run the two wires out through the firewall through an existing hole or to really do it properly, get the correct terminals and put these into the bulkhead connector and then under the hood untape the existing harness to add in the new wires and then re-tape it back together.
5. If later you upgrade to a larger alternator and related wiring between the battery and alternator the ammeter probably will not work as it is only designed to monitor +/- 40A of current.
6. If existing wires are used off of another gauge in the console, then the power wire is probably already protected by a fuse in the fuse block while adding an ammeter will require the addition of two fuses and holders or two fusible links where they connect into the cars wiring.
7. If there is a problem with something like the vintage air, headlights, or any other electrical device, it's nice to know how much voltage the cars system is producing to help with troubleshooting. Most electrical devices operate within a voltage window of let's say 8-15 volts which if you have a volt meter you can see this. With an ammeter, who knows what the voltage is as it only shows which way and how much current is flowing.