1991 Geo Storm brake and battery light stay on

Battery light coming on -you have a problem within the charging system and possibly a short circuit that's eating up the battery overnite. You might want to do a battery drain test see below

I would have the alternator tested at a autoparts store or while the veichle is running put a voltmeter on the battery posts and make sure you are getting more than 12 vlts dc.

I'm having the same problem with '93 Storm. While driving, battery light and brake light come on simultaneously, stay on, and drain battery. After a few miles, the check engine light comes on. Eventually, battery is drained. Charged battery overnight, and it ran fine for a couple of days. But then it happened again. Trickle charging it now. Comes and goes. If it's just the charging system, why would the brake light indicator come on too? Should i find the switch on the hand brake and see if it or the wiring there is shorting? When it was happening, brake indicator light didn't change when i checked the hand brake. Stayed on no matter what I did with the hand brake.