battery?

04 chevy trailblazer, 6 cyl

The car needed to be jump-started twice within one week. It started both times instantly with a boost. I took the battery to Azone for a test and it tested ok. Fifteen minutes later, with the battery reinstalled it would not start. I got the typical nearly dead battery sound, a continual clicking as long as the key was at start. I noticed the dash meter read 9 V with the key at run, so I decide to charge the battery. One it started charging I thought about the 9 volt reading and decided to look again, because I could not believe it was fine minutes earlier and now only read 9 volts. After charging less than a minute, I disconnect the charger and turn the key to run. Now it reads much higher than 9 volts, so I try to start it and it starts.

I double-checked with my meter and the reading is 12 volts off and 14 volts running. I have not had another no start condition or a repeat of the 9-volt reading.

I did not check the connections at the starter, since it is buried behind some sort of mudguard. If I had not seen the 9-volt reading or had the instant response with a jump I would be looking at the starter.

Any ideas?

 

It does sound like a cable connection problem. It may be fine now, but could resurface at any time. Make certain that the cable clamps and battery posts are clean and secure.

While you have the cables off the battery, take the time to check out, clean, and re-tighten the other end of both the positive and ground cables. Beats being stranded at the worst possible time.

 

Key off should be reading slightly higher than 12v, about 12 1/2 or so; but I concur with the cables/connectors as a possible cause.

 

I'm gonna say the battery has a bad cell. The voltage readings will be in spec, but the amps will be low. You need amps to turn the starter.

 

yep i would guess bad cell too im suprised the positive terminal isnt leaking acid too

 

I will check the cable connections at the starter and ground on the body.

I first suspected a bad battery, but don't understand the occasional rather than consistent occurrence.

 

Strange that it's intermittent. If the battery had one or more bad cells, they usually show a lower voltage and tend to drain the battery. It is generally a constant low voltage and/or battery drain. Your problem still sounds like corrosion or a dirty connection either at the starter seloniod or engine ground.