Not very accurate but you will be able to tell if your charging system is working since the voltage should read between 13 to 14 volts depending on temperature. Mopar use ammmeters up into the 70's. Solder the spade terminals to the wire ends. The generator may not have much output near idle speed, so the system voltage my hover near 12 volts at idle. These gauges can be mounted in-dash or in Auto Meter mounting solutions panels, cups, pods, etc. Be sure there is adequate internal clearance for nut and sender.
In a car, it may not happen overnight, but if it sits for a few days. Note that terminal voltage is measured between points a and b. You put a loop around the wire and measure the amps remotely. Step 4 - Connect the Ammeter to the Alternator With your positive battery terminal now connected to the ammeter, you are ready to connect the next wire. Chevrolet changed the design in 1965. I probably wouldn't worry much if you put a fusable link at the alternator, so that melted first. All seems well and truck runs and charges with no burning effect.
Finally, connect the orange or white wire to whatever you want to measure the voltage of. It is quite a fun thing to do on your car. Im not afraid of the ammeter causing problems, but would like to play on the safe side. This is the 3-wire version of the volt meter, two wires are used to power it and the third wire is used for measurement. The three quantities on the right-hand side of the equation are now known or measured, and emf x can be calculated. A voltmeter is a great accessory that will help you determine how well your and alternator are working.
The volt meter is a high resistance low current device which can be connected directly across the battery. Also, you need to size it properly. Step 10: Find the wire that goes to the lighting circuit. With the unknown resistance Rx in the circuit, R 3 is adjusted until the galvanometer reads zero. Lift the cable from your battery, move it outside of the battery box and close the lid of the battery box. I like to solder them and use heat shrink.
Vintage generators are also rarely found with more than a 40 amp output the largest I've ever seen was a 50 amp unit , with most common units limited to only 30 amps, so finding a gauge with enough current-carrying capability shouldn't be hard. Anybody who knows about electrical should know that. You could otherwise connect the volt meter closer to the main battery cable for a lttle better reading of actual battery charging or discharging condition. Be sure that body or mounting flange of sender is grounded to suitable chassis ground. If the volt meter reads 12 volts or more the battery is near full charge. An ammeter has to be hooked in series to work as it reads current flow through the gauge and a voltmeter gets hooked in parellel as it hooks across a circuit to read pressure volts.
You can connect to the battery but there would be a small current draw ma all the time. Probe these wires with a multimeter to find a wire that has power to it without the key being turned on. For me, it's easier to wire the alternator +bat wire to the starter through a fusable link wire to the solenoid, then it is to bring it into the interior, and then back out to the solenoid. If perchance you add more lights or accessories to the vehicle, such as high power driving lights or a modern radio with high output amplifier, the total power consumption may exceed the generator output. Since R and r are in parallel, the voltage across them is the same.
Step 11: Run a wire from where you are mounting the gauge to the lighting circuit wire. The length of time you can get away with this depends on the battery storage capacity and the amount of current being drawn from the battery. Removing the ammeter and just connecting the wires together has removed the gauge but not all of the current running under the dash. Step 5: Decide where you want to install the gauge. Voltmeters and Ammeters: A brief introduction to voltmeters and ammeters for introductory physics students. Probe the connector for a wire that has power with the key off and does not drop to 0 when the engine is started. When you blow the horn it will dip just slightly lower.
Charging systems are considered good when putting out 13-14 volts at about 3000 rpm or so depending on the bike. If the battery happens to be significantly discharged, then the volt meter could read a little less than 12 volts even when charging. I'm pretty sure there are at least a few cars built before 1955 that managed to survive having amp meters. Step 18: Connect the three wires to the gauge. A voltage source connected to a long wire resistor passes a constant current I through it. Does having a internal regulated alternator change the situation? The amp meter actually held up pretty good under that catastrophic load.
When that happens the marginally excess power required will be drawn from the battery. Now with a volt guage there might be some different method of measurement or possibly a relay. That is my thought on the gauge swap. Of course, you can place the voltmeter under the dashboard on the right-hand side as well. Remove ¼-inch of insulation from the wire at the gauge and install an eyelet. About the Author Don Bowman has been writing for various websites and several online magazines since 2008.
The heart of most analog meters is a device called a galvanometer, denoted by G. You can connect it to a regular switched power source, but the light will stay on whenever the car's running, and won't brighten or dim when you adjust the dashboard lights. Mount the voltmeter with the screws provided. Just replace the fuse, do the right connection according to diagram and test it again. Army aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam.