Among the systems that get very little attention in any performance car is the electrical system. For the most part, electrical systems function fairly efficiently, but there have been many advances over the last 30 years, so there are several areas that could stand improvement. Let's go over some of these and what you can do to make the electrical and charging system perform up to the level of the rest of your performance ride.
Charge ItThe basic automotive electrical system employs a battery, starter, and alternator. The alternator is the heart of the system, since without it, you won't get far. Early alternators were a vast improvement over their DC-generator forebears, with most alternators cranking out a maximum of 60 to 70 amps. This was because they were only asked to power the headlights, heater, and maybe an AM/FM radio, and none of these demanded high-amperage output at low speeds. But today's cars usually include air conditioning, high-output electric fuel pumps, and twin electric fans, not to mention a thumper stereo and other electrical accessories. So high-amperage output at low engine speeds is now in great demand.
Given this increased demand, late-model internal regulator alternators are now designed to pump near-maximum output at idle. This is a great reason to switch to a later-model-style alternator that can handle the load of a typical electronically enhanced street machine. Add up the load of a pair of 20-amp electric fans, a big electric fuel pump, headlights, heater or A/C fan, and a few amps for the stereo and you're looking at a load in excess of 60 amps. This is far greater than the max output of a '60s alternator. There are several companies now delivering high-output alternators, including Powermaster, Bosch and Performance Distributors, as well as the OEM's. Don't be fooled by the small diameters of these late-model alternators. These smaller units are capable of 100 amps or more output even at relatively low alternator speeds.
Some confusion exists in the area of one-wire alternators. These are self-energizing alternators that do not require a separate feed-wire connection to energize the alternator. The term "one-wire" comes from the fact that the heavy alternator charge wire is the only wire connection required to the alternator. Most factory alternators are generally three-wire connections with a pair of small wires that complete the control circuit.
OEM style internal regulator alternators use an external 12-volt connection to signal the alternator to begin charging the moment it begins to spin. One-wire alternators instead rely on attaining a given internal speed to create a sufficient internal voltage to begin the charging process. One-wire alternators need to achieve a sufficient rpm to begin charging, usually around 1,500 to 1,800 engine rpm. So the only thing you have to remember when using a one-wire alternator is to lightly rev the engine once after starting in order to trigger the charging circuit. Some companies like MAD Enterprises suggest that the one-wire alternators do not do as good a job of maintaining system voltage and can be difficult to replace in the field, which is why MAD suggests using a three-wire alternator instead.
Grounded For LifeAnother important area within the electrical system that rarely gets attention is the ground circuit. Even the simplest electrical circuit requires a power source, wiring that connects to a load (like a lightbulb), and wiring to complete the ground circuit back to the battery. But when performing electrical-system repairs, it's the ground circuit that is often ignored. The classic example of this is a dragging starter that begins after the battery is relocated to the trunk. The installation often includes a large multistranded positive battery cable from the battery to the starter, followed by a wimpy ground strap usually connected to a corroded sheetmetal connection. This creates a poor ground circuit that causes grief once the engine warms up and resistance increases. The fix is to add several large ground cables between the engine, the frame, and the battery to ensure a solid ground circuit all the way back to the battery. If you have any questions about the validity of your circuit, perform a voltage-drop test (see "Drop It").
Getting ConnectedAll electrical devices require dozens of feet of stranded wire and connectors to make all this happen. While voltage loss is proportional to increases in wire length, the big voltage-drop culprits are connections. This is especially true with poor connectors or hastily performed temporary fixes that become permanent repairs. A poor connector or a power feed line that has been spliced several times can quickly become a focal point for many electrical problems. There are several ways to make a good electrical connection, but we'll go over just one. The key is to make the connection as permanent as possible in order to prevent problems from occurring later.
The best way to create an excellent electrical connection is to use quality terminals instead of those cheesy plastic-coated connectors. Stick with the standard non-insulated connectors. Use a quality wiring stripper and crimping tool, and if you're really motivated, you can also solder the connection to ensure minimal voltage loss. With that done, you can finish the connection by covering it with a length of shrink tubing.
Most musclecars can benefit from a live 12-volt power source under the hood near the battery. If you've ever seen a positive battery terminal with six or eight different wires leading off the terminal, you know that it's less than attractive, let alone barely functional. The much cleaner alternative is to mount a terminal near the battery that is fed from a large 8-gauge wire from the battery. This terminal can then feed high-current items like an MSD-6 box, stereo amplifiers, nitrous solenoids, and electric fans.
Adding CircuitsAnother difficulty facing car crafters that wish to upgrade their older supercars is that there are usually very few extra electrical circuits in these older cars that offer fusible circuit protection. Adding extra circuits on an as-needed basis is clumsy. A much more expedient method is to employ one of those add-on circuit boxes available from companies like Painless. These are pre-wired circuit boxes with built-in ATO-style fuses that can manage several circuits without overloading your existing fuse box. The biggest hassle would be finding a place to mount the box. Then all you have to do is wire up the circuits you want to add and you're ready to run. Painless offers these slick units in universal 3-, 7-, and 12-circuit blocks complete with fuses and a heavy-duty relay. Painless even offers a 12-circuit universal pre-wired fuse block that will replace your existing fuse box. These kits are very easy to install and will give a professional look to your wiring system.
Like most things in life, it's the little things that can trip you up and make you miserable. Eliminating those pesky electrical gremlins is about knowing how to do the job right the first time. Apply a little bit of electrical savvy to your next wiring job, and you won't have to pay the consequences of being stranded alongside the road with a melted harness.
Drop ItOne of the most valuable and easy tests you can run on any electrical circuit is a voltage-drop test. All you need is a digital voltmeter and a little bit of time. The voltage-drop test measures the amount of voltage that is lost in the circuit due to high-resistance connections, bad cables, weak switches, or a poorly functioning component.
The simplest test is to measure the amount of voltage drop that occurs between the alternator and the battery. Start the engine, and using your digital voltmeter, measure the voltage at the back of the alternator by placing the red lead on the alternator output terminal and the black lead on the alternator case for a ground. Then measure the voltage at the battery with the red lead on the positive and the black lead on the negative battery terminal. On our test Camaro, the alternator cranked out 14.4 volts, but the reading at the battery was only 13.5. This meant there was a 0.9-volt drop between the alternator and the battery. An acceptable voltage drop is more like 0.4 to 0.5 volt. We either have a wire with high resistance or a bad connection. We've seen as much as a 1.5-volt drop on an early Chevy musclecar traced to an undersized fusible link.
Remember that voltage-drop tests must be performed while the system is operating. Another popular voltage-drop test is with the starter circuit. GM cars are famous for "heat-soak" problems that occur because resistance increases with temperature. Again, the test can only be performed with the starter in operation. This produces a current flow and therefore a voltage in the circuit. To perform our test, we disabled the ignition, set the digital voltmeter on the millivolt (0.001 volt) scale, and tested each series of connections. For example, we tested the voltage drop for the positive battery cable between the solenoid and the positive battery terminal on a '68 Camaro. While the positive battery cable looked fine, we discovered a massive 1-volt drop in this cable alone! In order to record these high readings, we had to switch to the 2-volt scale on our multimeter. Combined with the smallish negative cable, the two cables alone produced a massive 1.6-volt drop in the starting circuit. The owner noted that the car had always had difficulty starting when it was hot. An acceptable level might have been around 0.20 to 0.40 volt for each cable.
