Snapped Alternator Belt... 86 560sel

[Lurch]

A quick question regarding battery endurance.

Belt busted while driving on highway last night. My Mechanic has ordered parts and I will be taking it in Tuesday to replace all belts. I hooked up to a second car to recharge my battery (not good to stay discharged from what I understand). The battery is a year old OEM battery (great huge thing) that should be in good shape as there have been no electrical problems until the belt went last night.

Rather than towing, I'd like to drive it over to his place.

What kind of maximum running range would I have on battery without alternator? (Assuming full charge with no headlights, blower, radio, etc...)