Why my battery light come on and off I put brand new battery and alter

Hi @mookman,

Check that the alternator’s voltage regulator’s output is OK.

With the engine running place a voltmeter across the vehicle’s battery terminals and measure the voltage.

Be safety aware when you do this as the engine is running. Apply the handbrake (aka parking brake, emergency brake) firmly and do not wear any loose clothing etc, that may get caught up in the engine

It should be between 13.8VDC - 14.5VDC and it shouldn’t be outside these parameters

If it stays within the parameter, hopefully steady there there may be a fault in the wiring to the ECM (or the BCM, don’t know for your vehicle) modules or in the module that sends the signals to the instrument panel light regarding the state of the output of the voltage regulator that is usually inbuilt with the alternator or perhaps even in the instrument panel itself - loose connection perhaps. Does the light stay on steady when you just turn the ignition to On and not start the engine?

If it goes below the lower value or above the upper value get the alternator checked out.

If you haven’t got a Voltmeter go to an auto electrician and get them to check it out.