Dead Battery?

PME_68

MEMBER
MAZDA TRUCK

I own a 99 Mazda b2500, with 80,000 miles on it. Today I went out to start it and it was totally dead. The battery in it, is only six months old. The interior light, radio and headlights do not work. Prior to today, I have no problems starting the truck, it has ran fine. I took the battery to be tested at Wal Mart, where I bought it. They said the battery was fine. After leaving there I thought, if the battery is good, then wouldn't I have functioning lights and such. I then went to Auto Zone and they tested it and said the battery is dead. I haven't purchased a new battery yet. I am wondering why after six months is the battery already dead. I haven't left the lights on, radio playing or anything like that. What could drain the battery like that. Also, it won't even jump start.

1 Reply

BACKYARDMECHANIC

MECHANIC
337 POSTS

If the battery is completely dead then It may not start even with a jump. As far as why the battery is dead it can be a few causes, like the charging system, bad battery, bad wiring or a short/drain. The first thing you need to do is either get the battery charged or replaced if it doesn't take a charge. You can not perform and test unless the battery is fully charge. Also check the battery cables and make sure they are clean and tight. With a volt meter and the car running (if the battery is completely charged the car should start) check the voltage out put of the alternator by connecting the meter to the battery. The reading should be between 13.5 and 15 volts if the alternator is working properly. If not the alternator needs to be replaced. If the alternators is good then you may have a short or drain on the system. You can check for a short /drain by connecting a 12v test lamp (in series) between the postive battery cable and the postive terminal of the battery. When conducting this test make sure everything is off ( doors closed and hood light disconnected) or you will get a false reading. If there is a short the light will light brightly. A dim light or no light is normal.