I just bought a 97 Tour Sport that came with a bad alternator. The housing had cracked and the pulley was frozen, so I also had no power stearing
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With a Diehard batt rated at 490 CCA I drove it about 15 min, roughly 10 miles. This was at night so I had to run my headlights, and was running the fog lights for fun, I also stopped at a gas station and had to stop and start the car an extra time :-/. I also punched it from about 15 mph to 65 or so on the entrance ramp to the highway. Just before the battery died I hit the turn signal to change lanes and the tac dropped to 0 RPM every time the turn signal lights turned on. The motor was still running though not making much power. At this point I shut the motor off so that my lights had enough juice to be visible, pushed the clutch in (5-speed FTW), and coasted to the side of the road. 10 min of charging the battery via jumper cables off my bro's car I did a dig-65mph punch to get back up to speed and had the car go about 4 miles till the tac simply dead lined. (This is your warning that the motor is about to stall on you, which happens quickly afterward.) Again I shut the motor off (not losing my power steering since the serpentine belt wasn't on at all) and coasted to the side of the road. Charged the battery for 15 min off the bro's alternator this time, babied the car up to 75 mph (roughly 3-3.5k RPM at 75 mph if I remember right) and the car went about 10 miles before it died again. I did another 15 min charge and babied the car up to 55mph, which is all the faster I went. Car ran for about 15 miles, rinse and repeat that last charge and I got to my co-workers house.
I also drove the car like a grandma with a fully charged batt about 30 min, 15 miles, and made it without any problem. I work at Sam's Club in Tire and Battery and drove the car there, I had my co-worker charge the battery when I got there and he said it only charged for 5 min on our fast charger, so I might have been able to get back home without charging if I had continued to baby the car.
The RPM's *greatly* affect battery life and lights drain it noticably faster. I was forced to drive at night because it was the only time my co-worker could work on the car that I could drive it to him, AVOID DRIVING AT NIGHT IF YOU CAN!!!
My friend/co-worker happens to be a certified mechanic and installed a new alternator for $100, after he was done he said he was never putting another alternator is as it involved removing the passenger side drive shaft and lower ball joint. It was a 6 hour long project for him, and would have cost well over the $270 final bill (including alternator) if I had gotten it done by a shop.
Cliff Notes: Battery should last 45min-1h if you drive it *easy* without any power draws except the essentials. To be on the safe side find a friend/family member to follow you and bring jumper cables in case you need to re-charge the battery mid trip.
