What does it mean when the battery light comes on And stays on

The battery light is for the charging system when it comes on when the engine is running it means that the altenator and or the wiring to the regulator rectifier is faulty Until you get them fault found and repaired or replaced the light will still come on or stay on Check the drive belt to the altenator for correct tension

Maybe.
It means the alternator is not charging the battery.
The battery could have a dead cell, or the alternator could be faulty, or a wiring problem between the two components.
You would need to have the battery and alternator tested.

If the alternator is charging the battery, the light may mean the brake fluid is low.

If the battery and brake lights come on it usually means that the battery isn't getting charged. Either the belt for your alternator broke, or the alternator is not putting out power to charge the battery.

All cars have a battery light on the dashboard that is designed to warn you if the recharging system fails. A simple circuit looks at the voltage that the alternator is producing, and turns the battery light on if it is low. The battery light indicates a battery charging problem. If the battery light comes on and stays on while you are driving, the most common cause is a broken alternator belt. Total failure of the alternator is another possibility.

This generally means that you have a problem with your brake system. I would try opening the hood and checking the brake fluid level on your Avalon.

When the battery light comes on it doesnt mean that the battery is bad,its a means of saying low voltage in the system,test the alternator-or replace it,but 1 way to check it is to hit it with a hammer lightly on a sturdy part of the caseing,then start it to see if the light goes out,its most likely the brushes bad.

The battery light indicates a battery charging problem. If the battery light comes on and stays on while you are driving, the most common cause is a broken alternator belt. Total failure of the alternator is another possibility.

From: www.howstuffworks.com

Hope this helps. If possible, can you please rate my response, thanks!

OpenSource13

Disconnect the negative battery terminal and put a test light between the battery and the wire. If light comes on fairly bright that means that something is staying on in the vehicle. Start to pull fuses till light goes and that will tell you which circuit to look for. Could be something like a glove box light staying on that you can not see.

When the light comes on it means that there is a problem with the
charging system. Could be a number of different things. First check your fuses. Then the belt that drives the alternator for proper
tension. If you find nothing there then take it to a reputable garage
and have the charging system checked. Good luck. Neil W.