91 grand voyager

First of all let me say hello to all as I am a new member here. I ahve recently aquired a 91 grand voyager that sat for about 6 months. just put a new exhaust system om converter back. yesterday it started but then died, had to jump it to get running. after about 5 minutes driving (night time) just shut down and battery was completely gone. jumped again and started right up but again died. ANY IDEAS I am auto repaire challenged so please any help is appreciated
thanks

Bad battery perhaps? Or altenator not charging properly.

Unless the car was started every two weeks or so or the battery was put on a charger regularly, chances are the battery is bad. Lead-acid batteries don't like to sit and will often self discharge to the point that they will no longer hold a charge.

Lee Westfall

could also be a bad alternator or voltage regulator. check these parts. and if all else fails do some test with a mechanic.

thanks for all the replies, problem found and fixed. there was plastic melted on the positive post. spent 15 minutes with a file cleaning post and voila..... how it got there I have no idea but has been fine since it was cleaned. problem now is replacing back 3 plugs on the engine.

heeellllpppp