Battery light comes on and off

You probably need to check your charging system. Any applicable trouble codes? To check for codes, at the least, you need an obd2 code reader that will work with your vehicle. Some of the national brand autostores used to check trouble codes for free.

That has nothing to do with the condition of the battery. That means the generator isn't recharging the battery while driving. For intermittent problems, the most likely cause is worn brushes. They can be replaced easily by replacing the voltage regulator which is bolted to the back of the generator. The brushes come as part of the regulator. Most people replace the entire generator.