Why is my new battery toast?

Old battery of about 8 years died. I replaced it. Two weeks later, my new battery is dead. The car will jump start, and run fine, but as soon as the car is turned off it won't restart, even with 20-30 mintes of run time. with all accessories on, engine running the voltage at the battery terminals is 14.7 volts. Turned off, engine off, the battery read 9 volts. Is my new battery junk or could the voltage regulator be bad and cooked both batteries? I need to have a working car so please help.

Reply to
celica91
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Possible causes are that the replacement battery is bad, that the voltage regulator and/or the alternator are bad, that there is a poor connection to the battery cables, and a poor ground connection for the battery.

Reply to
Ray O

celica91 wrote in news: snipped-for-privacy@no-mx.forums.yourdomain.com.au:

As Ray indicated could be bad battery. Had similiar experience on my '94 Pickup. Battery less than a year old from Advance Auto. Slow crank\no start in the am few weeks ago. Took battery back after checking the items you also checked & got a replacement for $0.88. Also seems to crank much faster & stronger now. dc

Reply to
doncee

Corrosion.

Take the battery connectors off of the battery and clean them using baking soda and water. Rinse them and reinstall them. Be careful not to get any of the baking soda and water on the battery. Put a light coating of some type of anti-corrosion compound on them after everything is put back together.

Your terminal voltage is about right with the engine running so the alternator and voltage regulator would seem to be fine. A terminal voltage of 9 volts with the engine off would indicate a completely discharged battery. Corroded battery connectors will prevent the battery from being recharged but you will read normal voltage as long as the alternator is supplying power to the accessories.

Jack

Reply to
You guess

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