Run a wire with a fusible link from the big post on the rear of the alternator to the battery or big post on the starter. Me, I just wired in my Ammeter and did it carefully, I insulated every damn thing and when I was done I used some strips of black duct tape to cover the back of the thing. Trade marks and trade names used for reference purpose only. Might work, but will probably overcharge due to 12v going to the white exciter wire. Not much info on the web about this. The original gauge in the car only goes up to 30 amps, so the first time the battery gets low and the alternator starts to put out more then the gauge was designed for, you have a fire.
As everyone else has suggested, I've also kept the original power wire with fusible link in place. Alternator, you want a voltmeter. The ammeter was the fuse. Fixing them might just get you amped up! I need to upgrade the charging cable that runs from the back of the alternator to the power block near the battery. The easy way to do that is to wire a gauge for your alternator, which is called an voltmeter. Happened coming off the truck.
An ammeter monitors the flow of current into or out of your battery. As you can see, the load could easily reach 90 amps or more. Use the shunt type but add an inline fuse to the wire going to the gauge. I have a 2004 Silverado and I just upgraded the alternator to a 210 amp high output for my sound system in the truck. But there is a work around. Powermaster says this value is usually no more than 20 percent.
It's how it's currently set up in my Firebird and I can definitely say I don't have an overcharging problem. Every schematic I have seen shows either a 1 wire install, or an indicator light, again I have neither. A volt sensor can be added to the new alternator for volt gauge or warning light functionality. Crimp a wire terminal onto the end of the red wire coming from your amp gauge. That was the best thing since pizza and beer. A simple fuseable link and I bet you'll never have to replace your amp meter. For restorations, most people tend to stick with what the factory offered, and both Tuff Stuff and Powermaster can help with those applications as well.
You should never assume that the mounting bolts provide a clean ground, and therefore, a second ground wire should be used to provide a ground connection for the alternator. I need to upgrade the charging cable that runs from the back of the alternator to the power block near the battery. Decide if you really need one. One exception to this is , rated to charge 80amps at 750rpm. This new alternator is a 170 amp 6 phase alternator that will put out 120 amps at idle, the stock alternator is only 105 amps total. But to get the voltage coming out of the alternator, you really have to connect the voltmeter to the battery and therefore the ignition wiring in the vehicle, since that's what the alternator is feeding.
Tighten your battery terminal for good contact. Also the wire from the ammeter does not normally connect directly to the battery, but usually to the battery cable where it connects to the starter. Remember that any electrical circuit requires a return, or ground, side—a portion of the circuit that is completely ignored. You put a loop around the wire and measure the amps remotely. It provides positive assurance that no 'hot' wires will get chaffed and cause a short. The older mopars with ammeters came with 37 amp alternators.
Many factory alternators from the classic car era had 14-16 gauge wires, which are not sufficient to handle higher alternator outputs. It must be switched, or else it will drain the battery overnight. Racecarl, Your alternator might have the capacity to put out 72 amps, but that won't happen unless your old truck has the need for this amount of power. A very common problem with many older street cars is an undersized alternator charge wire between the alternator and the battery. Below is a chart with the recommended wire gauge for your one-wire alternator. That is to say, run dedicated ground wires to every component that might normally just be grounded to the body or chassis. I think if you clear out the area behind the ammeter and make sure nothing is flammable, it can be pretty safe.
The red wire leaving the scene goes right to the battery and the white wire is still hanging out in the wind. Generators and alternators work differently, so the type of gauge you need to monitor them is different too. Similar to whats already posted. A big part of the problem was a poor ground circuit. It was ruined by the alt. I think one of the problems, is that a lot of schematics in books and old cars didn't fuse this circuit.
On my cars, I make sure every connection is tight, and I use this incredible stuff called No-Ox-Id that looks and feels kinda like ear wax, but once you put a light coat on every connection, it'll protect it against moisture and corrosion and insure a good connection for years to come. It happened as people replaced generators with alternators and alternators with larger output models. On the left, a standard guide for wiring the alternator with the battery close by; on the right is a guide for remote mounted batteries. Adding a 70 amp alternator is a fire hazard on those cars without a shunt. I am using a kit from keepitclean, and they leave everything to the imagination! I like to run new ground wires of the proper gauge back to a common bulkhead on the firewall usually that is in direct contact with a heavy gauge battery cable going to the engine block and meeting the battery's ground cable.
If not add resister to limit current, you do not want the gage circuit to be the load circuit. I've installed ammeters in my cars before and never had a problem with one. . The amp meter actually held up pretty good under that catastrophic load. Don't blame it on the meter though, it's not the meter's fault, it's the electrician's. Since maximum demand will most generally occur during high-heat situations, it would be wise to include an efficiency loss factor when considering a high-output alternator.