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car battery keeps failing! help!


cookci
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basically my car battery keeps going flat when the cars sat for a few days so i had it tested which showed it needed replacing...

 

i replaced it with a halfords HB005 for £34 on trade but the problem is still occuring. i tested the new battery (using the halfords battery tester) which said it needs charging. Id driven the car enough to charge the battery.

 

ive put a multimeter accross the battery whilst running and it shows 14V, does that mean the alternator is ok?

 

im fubbered now unless the halfords tester is incorrect

 

 

any suggestions?

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Hey. I know sweet FA bout the technical stuff on cars but I had a similar problem a few years ago on a motor id rather not mention. Anyway it turned out to be the stereo wired up wrongly. I know thats probably not the problem but maybe its worth checking. Thats all I got.

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You need to test what the drain is when the car is off to see if there's a short somewhere.

From chassis ground to +ve should be 0.x volts or less. If it's showing a higher voltage then you need to start working out where the drain is. (Make sure that all internal lights etc are off when testing of course)

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  • 2 weeks later...

FYI, mine starts charging at 14.6v immediately after the starting, then after 5 minutes drops down to just under 13v. It is still putting in a small amount of amps into the battery and it doesn't go flat, so don't consider that 14v is actually putting the amps in.

 

Have you got a big stereo, lots of gauges/electrics, electric fans and twin pumps? Or is it just standard? Have you got a manual or auto? As the Auto puts out an extra 10amps.

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ive got an auto. I checked the drain whilst stationary and it was neglible.

 

 

recently ive switched the alarm so maybe thats fixed (had a toad now got a code). The car has been sat again now for a few days so ill have to wait and see

 

thanks for your help

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