Voltage drop is an all-too-common issue plaguing commercial vehicles. It occurs when there’s a decrease in the amount of available voltage in the cables and connections from a source to the component—specifically, between batteries and the starter or alternator.
There are three common causes of voltage drop:
- Undersized wires and cable: Often the original cable set on a commercial vehicle can’t keep up with the electrical load demands as changes are made, such as upgrading the alternator or adding electrical equipment, including navigation, entertainment and other systems that enhance comfort and safety. Any time upgrades are made, it’s important to check both cable gauge and length to ensure they can handle the increased output by performing voltage drop testing.
- Loose or broken connections: There are many connections on a vehicle that can become loose, frayed or broken. This can happen over time from wear and tear, improper torquing, or vibrations on the road.
- Corrosion: Corrosion—due to snow, rain, salt and other environmental hazards—at electrical terminals and cables can create voltage drops because of an increase in resistance.
To prevent issues/failures caused by excessive voltage drop, be sure to perform voltage drop testing anytime you’re replacing batteries, servicing or replacing the starter, or upgrading the alternator.
Voltage drop testing should also be part of your regular preventive maintenance. Watch our
Voltage Drop Test Tech Tip video for step-by-step guidance.