changing system problems

[TBroccoli]

Ford f 150 4x4 1997. I just put a new starter in last week. The battery tested good. It is one yr old. Tonight I went and picked up the boat and towed it to get gas then groceries. When I went to start it the battery was dead. It jump started. On the drive home I noticed the charging gauge on the dash was moving up and down. When at high revs the gauge pointed up. At idle with the ac on the gauge was low. Is it just a dead battery or do I have a problem with the altinator?
Tom

[mrfixxall]

Ford f 150 4x4 1997. I just put a new starter in last week. The battery tested good. It is one yr old. Tonight I went and picked up the boat and towed it to get gas then groceries. When I went to start it the battery was dead. It jump started. On the drive home I noticed the charging gauge on the dash was moving up and down. When at high revs the gauge pointed up. At idle with the ac on the gauge was low. Is it just a dead battery or do I have a problem with the altinator?
Tom


tom a alternator is designed to maintane the batterys voltage,,if you just jumpped it and drove it then the battery wasnt fully charged..charge the battery over night and have it load tested...A,,you may have a assory on that killed the battery or b,, the battery may be junk.

[TBroccoli]

Thanks for the help. I had the charging system checked and found out the alternator was failing. Replaced and was able to make it to the beach by noon. Thanks,

Tom