battery indicator-real simple

I have a 99 olds intrigue and while driving down the road this weekend what I think is the battery indicator came on. It is a red box with a squiggly line through it. The reason I have to ask is my owners manual was tossed when the car was stolen from me ( I should have been happy) and I can't find it online. The dealership (chevy) says they dont know and to buy a manual.
Why would the light come on? It was after about 20 minutes of highway driving. It came on this morning after 5 minutes.

I thought the battery light was a square box with the + & - sign in it. What you are describing sounds like the low coolant light. If someon deons;t answer your question, i will check my owner's manual tonight for you.

Yeah that definitely sounds like the low coolant light instead. Check your coolant before worrying about the battery.

Yeah that definitely sounds like the low coolant light instead. Check your coolant before worrying about the battery.

Or, if you're like me and changed the coolant recently, you have air in the radiator. If that's the case, the bleeder (on my car facing the windshield) is on the top left (passanger side) of the radiator. It's a wing style nut.

With the engine cold, start the vehicle, get out and open the bleeder valve until the air starts bleeding. Don't open it too far or you'll get fluid instead of air. Once the air is out, you'll get nothing but fluid. That means you're finished.

<-------> 2000 Olds Intr 3.5L