Why is my car battery over charging

How do you know it's overcharging? It could have a bad alternator.

Hi,

Place the transmission in Park (or Neutral if MT) and apply the emergency brake and start the engine.

Then test the voltage across the car’s battery terminals with a Voltmeter and check that it measures between 13.8V DC and 14.5V DC.

If it reads more then 14.9V DC and the battery is losing electrolyte due to it being overcharged, then there may be a problem with the voltage regulator - example only.

Be safety aware as the engine is running

In answer to your other question

instement panel shows battery symble in red

usually a red battery warning light indicates that the battery is not being charged.

Have you checked the belt that turns the alternator is OK?

Check the voltage at the battery with the engine running. It should be 13.8-14.5V DC. If <13.8VDC it may be the voltage regulator or the alternator. If the voltage is OK it may be the ECM as it controls the warning light on the instrument panel.