Q: Alternator overproduces power above roughly 5,000 RPM, how badly do I need to replace it? Worst case scenario?

asked by on

2000 nissan Maxima, 165,000 miles Bought a used alternator around 150,000 miles

Basically pretty much only when I floor it (which is more often than your average driver for me haha) any electronics will go overboard for anywhere from a half-second to about two seconds tops. This includes the fans blowing harder, and the lights getting brighter mainly, and two lights will come on in the dash. It is fairly reproduce-able and not random. Could the ECU crash eventually?? : /

The alternator should not be putting more than 15.5 volts and 95 amps at 5000 RPMs. If the alternator is, then you need to replace the voltage regulator inside the alternator or replace the alternator. Make sure you have a battery that is fully charged and is good when tested with a load tester. If you continue to run the engine with the alternator above the 15.5 volts maximum (should be about 13.5 volts normally), then you may burn out components and it will cost you much more than a replacement alternator will. The ECU and other modules have protection for over voltage, but this protection may not provide long-term protection against voltage above the 15.5 volts may eventually burn out. I recommend having your electrical system inspected by technician, such as one from YourMechanic. They will be able to make a diagnosis and replace your voltage regulator or alternator if necessary.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Alternator overproduces power above roughly 5,000 RPM, how badly do I need to replace it? Worst case scenario?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Q: Car won't start

Hi there! This concern plagues many vehicles and may stem from either a failing battery, or some charging system component that is not charging the battery properly (e.g., a shorted circuit that drains the battery while the car is idle)....

Q: Q: Cooling Fans

Most Vehicles now have 2 separate cooling fans. One cooling fan is intended to come on when the engine reaches a certain temperature. The other cooling fan is intended to come on when the air conditioning is turned on. When...

Q: might need a new ECU

The vehicle will not start if it is not programmed to work with your vehicle key immobilizer. You will need to have the ECU programmed for it to work.

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.