Occasionally we get asked some eyebrow-raising questions, many of them associated with electrical systems. Once in a while, we get a question that we simply don’t know the answer to. When that happens, we go to the experts. This week, we have three quick questions with Powermaster Performance.
We’ve had a few questions from racers using boat engines in stock cars, and even one where a FWD Buick 3.8 liter was being fitted into a street stock, regarding alternators turning in the opposite direction. So we asked these questions of our expert.
OneDirt: Can Powermaster racing alternators run backwards?
Powermaster Performance: Yes, they charge in either direction. Pro Tip: Be sure to lock-tite the pulley nut on if running backwards.
OD: As it turns out, most automotive alternators are bi-directional and will charge in either direction. That doesn’t mean that they all will. You need to check with each manufacturer or an alternator expert about the alternator in question, and if it can operate in counter-clockwise rotation. Remember the cooling fan (if equipped) will be running in the opposite direction too. This could cause heat problems and as we all know, excessive heat kills electrical components.
We still have enthusiasts and race team mechanics that avoid electrical circuits. While we have covered it a few times, the questions about converting from a GM plug to one-wire alternator still come up. So, we asked our experts.
OD: How do you hook up a one-wire alternator?
Powermaster Performance: Simply run a charge wire from the battery terminal on the alternator to the positive terminal on the battery (or battery side of the disconnect switch). The one wire regulator is a self-exciting regulator, meaning that it has sensing circuitry for alternator rotation. As the alternator starts to spin, this circuitry connects the internal voltage regulator to the battery and turns the alternator on. When the alternator comes to a complete stop, this same circuitry turns the alternator off.
OD: If an alternator is tested and found to be charging 13.6 volts, is there a problem with the alternator?
Powermaster Performance: Not necessarily. The voltage can be low for several reasons. First, make sure that the voltage meter is measuring accurately. Check the voltage with another quality meter. Second, consider where in the system the measurement is taken. If this voltage is at the battery, check the voltage at the alternator. If there is more than 0.40VDC difference, the problem is in the charging or ground path from the alternator to the battery. Upgrade the cables, disconnect switches and connectors.
If the voltage is low at the alternator, then the alternator is not able to produce enough amps to satisfy demand at this speed. Either change the speed with different pulleys, or change the alternator to one with more output at this speed. Keep in mind that all alternators have an output curve. Some curves rise abruptly at low speed and level off. This type of winding is more for low speed operation. Other curves rise more slowly but peak at a higher point. This type of alternator is designed to run fast. It is important to tune the alternator speed to the alternators power characteristics and the vehicles amperage requirements.
For more information on Powermaster Performance and their line of racing alternators and starters, visit them online at www.powermastermotorsports.com