Battery not charging light came on - 2006 Isuzu Ascender

There are several potential issues that could cause the battery light to come on and flash rapidly in your 2003 Nissan Altima 3.5. Some possible causes include:

1. A failing alternator: The alternator is responsible for charging the battery, if it is not working properly, it may not be able to keep the battery charged, causing the light to come on.
2. A failing battery: If the battery is not holding a charge, the light will come on.
3. Loose or corroded battery terminals: These can prevent the battery from charging properly and will cause the battery light to come on.
4. A problem with the charging system: A problem with the voltage regulator or wiring can prevent the battery from charging properly, causing the light to come on.
5. A problem with the battery sensor: A problem with the sensor that monitors the battery could be causing the light to come on.

the fuse is ok as you have a reading on the gauge
the problem is in the alternator or regulator or battery
charge lights work from a positive and a negative current flow
when you turn the key on the current flows in one direction through the light to the alternator and so it lights up
when the engine is running the alternator is charging ( normally at a higher voltage than the battery and so a current is directed back through the light to the battery
these two opposing currents mean that there is no current flow through the light and so it goes out
however if the batter has failed ( 9 volts is a good indication ) then the 14.5 volts will will produce a current back through the bulb and it will again light up
I would have the battery load tested as it may have an internal fault and not accept the charge from the alternator

Test the alternator. The battery light is for the charging system. Once the charging system is working with the engine running, the light should go off. If your light stays on with engine running, the alternator may need service or replacement.

To test the charging system, just put a voltmeter on the battery with engine running. The voltmeter should register at least 13.5 volts- alternator is charging. If you only show battery voltage with engine running, like 12.2-12.8 volts, the alternator or charging system is not working. The battery light should be on to signify this.

have the alternator bench tested as it may have a faulty rectifier pack in it
charge lights basically work by when not running the current flows from the battery to the alternator through the light
when the alternator starts to charge it puts a reverse current back through the light in opposition to the battery and so the light goes out
if the light stays on then that means that the current from the alternator is alternating and the battery is keeping it on.

Is the system charging? You should have 14.2 14.6 volts at the battery. The charge light is controlled by the alternator internally. If the charging system is working, you could have a bad diode inside the alternator keeping the light on or a short/grounded circuit to the battery light

Red light battery light in the car that charging system fault if you just want to charge a new battery they come ready for use

The BATTERY light indicates that your battery is not getting charged. There could be several reasons for this most probably your alternator, which generates the current to charge the battery when the engine is running. If the new battery is not getting charged, it will eventually drain not start your car. To confirm that the battery is not getting charged and that is the reason for the BATTERY light, put a volt meter across the battery while the engine is running. It should read around 13 volts indicating that current is flowing into the battery. If it reads 11 volts or less, that means the batter is being drained and not charged. Then have your alternator checked.G

The charge light comes on whenever the battery has a low charge.The alternator charges the battery.When this light comes on,it usually means the alternator isn't charging the battery.I would suggest having the alternator tested and replaced,if need be.

Nissan truns the brake and battery light on when there is a charging issue. When you say it wont start does that means it craks or no? If it does not crank I would attempt to charge the battery then try to start it and check the charging system.

1st thing to check would be the alternator, to make sure it's charging the battery. If it's not, the red battery light would come on. Most major parts stores offer free battery and charging system checks, they can tell you if the alternator is not charging. Have it checked asap, as the new battery will be dead soon if it's not being charged. countrycurt0