Battery charging

On my 1997 GMC Yukon the ammeter shows a continued discharge, about two ticks below the 14 mark. It used to stay right on the 14 mark. Two days ago I did leave the dome light on and it took almost 12 hours to charge the
battery with a 10 amp auto battery charger. I have also totally discharged the battery several times in the past. Could the battery be causing the ammeter to show a low charging rate. The battery is a 1000 amp warm 800 cold and about eight months old.
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Is it discharging at 12 volts or just not up to 14 volts while charging?
Most starting batteries are not designed to deep discharge very often. The batter may be toast or about to be. You can try trickle charging it slowly to see if it will get back up to a full charge. You can also go to http://batteryminder.com/faqbw.cfm#q7 to get some additional answers.
Mark http://www.marknorris.com/1987Blazer.htm

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According to the ammeter it is discharging while running because it is below the 14 mark. I plugged a volt meter in the cigar lighter and it says 13.8 while running at sixty miles an hour, but I don't think these things are accurate. I think I have discharged the battery too many times. I believe the charging system is OK because there is a red light that does not come on. I will try charging the battery real slow with an automatic battery charger and see what happens. I found a site on the internet that says a steady discharge can indicate a battery going bad.

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you don't have an ammeter, it's a voltmeter. 13.8 is fine if you have a load (like the lights on or the a/c Blower going). anything above 12 volts is charging, over 14.4 volts is frying your battery.
-Bret

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buy or borrow a mutlimeter... (they make some decent cheap ones at radio shack)... check voltage across teh battery terminals while truck is running. It must be over 12 volts to be charging the battery. Normal voltage while the truck is running should be around 13 volts or better. It you have 13 volts or better while truck is running then you have a problem with the battery. If you don't have 13 volts or better whille truck is running your problem is the alternator.
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having deeply discharged (deep cycled) a normal lead acid battery, its very likely that you've damaged at least one of the plates inside and the battery is toast.
it will continue to give you problems until you replace the battery outright. have the autoparts store load-test the original battery to confirm its "damaged plate" condition.
there is a reason that deep cycle batteries (which are designed to be deeply discharged over and over) are much more expensive!! :-)
Hamilton Audio Car Audio, Security & Performance

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with all due respect, most 'auto parts stores' cannot do an accurate test of a battery's condition
better to find a battery / starter / alternator specialty shop that knows the subject

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Interesting. most autoparts stores around here use the same wall-mounted battery tester/analyzer that most shops use. so how could they not do the same job as a shop??
I agree that if they use one of those bullshit handheld deals, the test will not be accurate. but here's a test for yourself:
drive the vehicle for a bit to bring it up to warm, and park it. open one of the doors to put the interior light on, and leave it. come back in 1/2 hr and start the vehicle. if the engine even hesitates for a moment to crank, the battery is weakened/damaged....you should be able to leave that domelight on for hours before ANY noticable drain. we see it in the shop all the time....doors open for a remote start or stereo, and a battery SOOOOO dead that it won't even power the vehicle.
our policy is to put the powerpack on a car that will have the doors open any length of time....this prevents ME from being annoyed by a dead battery :)
Hamilton Audio Car Audio, Security & Performance

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RE/

? ----------------------- PeteCresswell
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