Q) What is an alternator?

A) An alternator is an electromechanical device that converts mechanical energy into electrical energy. It is used to recharge the battery after starting the engine and to power the vehicles electrical devices while the vehicle is in operation.


Q) What happens if the alternator is bad?

A) A bad alternator will result in a discharged (dead) battery and cause a vehicle to not start or run.


Q) Will an alternator charge a dead battery?

A) Alternators are designed to maintain a battery’s charge, not to recharge a dead battery. Charging a dead battery with an alternator will result in premature alternator failure. When an alternator tries to charge a dead battery it must work at 100% capacity, but an alternator is designed to work at 100% for only short periods of time due to the heat it produces. It is always best to charge a dead battery with a battery charger prior to putting an alternator into operation.


Q) The indicator light is on. Does this mean my alternator is bad?

A) Not necessarily, an alternator is only one part of the charging system. Alternators need good belts, wiring, etc. in order to function properly. We have produced a very helpful step-by-step “How to Troubleshoot an Alternator Problem” video that can be viewed here: https://www.youtube.com/watch?v=nQysE2oJAuo


Q) Can I disconnect a battery with the engine running to test the alternator?

A) Don’t do it! You risk frying every electrical device in your vehicle. The second you disconnect the battery, the voltage regulator tells the alternator to put out maximum power. With no battery in the circuit to act as a capacitor, the alternator can put out up to 50 or 60 volts, depending on engine RPM’s. When the smoke clears, that “simple test” could end up costing you several thousand dollars for new electronics. This is a very bad practice and most likely will result in alternator or vehicle damage.


Q) The car’s battery goes dead overnight. Is the alternator bad?

A) This type of symptom is usually due to an electrical component staying on after the vehicle is turned off. This is referred to as Parasitic Battery Drain. We have produced a very helpful step-by-step “Testing for Parasitic Battery Drain” video that can be viewed here: https://www.youtube.com/watch?v=zdIKNnwEjIs