Alternator not charging the battery.

ANSWER : Hello. If the battery and the alternator are new and if it is verified that the alternator is charging then you have an issue with programming. When you replace the battery on this vehicle the computer needs to be reprogrammed to recognize it and to properly charge it. If this is not done then the computer will not turn on the alternator at the correct times an this battery light will come on. You need to have this programming done by a certified mechanic, like one from YourMechanic, who can come to you to [program the battery into the computer] https://www.yourmechanic.com/services/battery-light-is-on-inspection

ANSWER : We can repair this for you. The best approach is to return the charging system wiring to the original configuration that is documented in the Factory Service Manual. Once the physical wiring is in place, it is a relatively simple matter to use that same diagram to test charging system output and verify operation. Once everything checks out and consistent alternator output is documented, some final checks are needed to be sure there are no phantom loads or parasitic power draw when the vehicle is either on or off. If you desire to restore the vehicle to the original configuration and get the charging system working, please request an electrical component/circuit diagnostic and the responding certified mechanic will commence this repair. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : This is likely a sign of a failing voltage regulator. This is a unit that regulates the charging of the battery by the alternator. In your case, it sounds like the voltage output from the alternator may be much too high resulting in overcharging the battery and burning up wires in the process. I would recommend having an expert from YourMechanic come to your location to diagnose and properly test your vehicle’s charging system.

ANSWER : Hi There,
The first diagnosis of the bad voltage regulator is likely the cause of your charging system not properly charging the battery. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all. In some cases when a battery is too weak or damaged, it may no longer hold a charge for any length of time, in which case the alternator may be doing its job, but the battery is just simply too weak to hold a charge. In either case, I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

ANSWER : Hi there. To be honest, when the alternator tests as good and the battery terminals are good, this issue is typically very difficult to diagnose. In most cases however, this is either an electrical relay fault to the charging system or the wiring harness from the alternator to the battery has a short. It might be helpful to have a professional mechanic come to your location to complete a battery will not hold a charge inspection.

ANSWER : Hello, thank you for writing in. Several things may be going on. The installation of the new alternator needs to be verified, focusing on the electrical connections and the drive belt. Make sure the connections are clean, dry, and tight. Make sure the drive belt is routed properly and is tight on the alternator pulley (as it is what powers the alternator). If the installation was fine, you will want to make sure the alternator was not faulty from the factory. It is not common, but these issues have been known to happen. Most automotive parts stores can test the alternator off of the vehicle. If you would like more help with testing, contact our service department to schedule an appointment.

ANSWER : Hello.

If replacing those particular components did not correct the issue then the next thing I would look at is the vehicle’s voltage regulator. It appears that this engine’s electrical system is equipped with an external voltage regulator that functions, or malfunctions, independently of the alternator. The voltage regulator regulates power from the vehicle’s alternator, and can cause issues with the electrical system when it malfunctions. I would test it to see if it is functioning properly. It is a silver box that should be mounted somewhere in the engine bay, usually on a wheel well. A technician from YourMechanic can come to your home or office to replace your car’s voltage regulator if necessary.

Regards,
Eduardo

ANSWER : Hi there. The best way to diagnose why a battery would constantly drain is to review it’s job and how it is recharged. The battery is responsible for powering all electrical systems until the vehicle is started. At this point, the alternator takes over and also continually charges the battery while the vehicle is in use. A battery will drain when one of two things occurs. First, a battery will drain if it is constantly in use; supplying power to an electrical component even if the key is not in the ignition. Second, the battery will eventually die if the battery is not being charged frequently. However, since this is happening every two days, my initial thought would be that some electrical component on your 86 Olds is continuing to draw power from the battery. This is known as a parasitic drain. The best way to determine the source of this battery issue is to have one of our professional mobile mechanics come to your location and complete a battery will not hold a charge inspection.