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Discussion Starter · #1 · (Edited)
2004 envoy xl 5.3
Test shows 0.01 amp draw with no alarm in 10 amp mode
Test shows 0.51 amp draw with alarm on in 10 amp mode
Battery keeps dying overnight with alarm on
Battery tested good at wally world
 

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2004 chevy trailblazer_lt
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Welcome to the Forum!

Have you had the alternator checked to see if it is actually charging the battery?

Now for some numbers.

Assuming you have a Group 78 battery installed and that it is fully charged, the Amp-hour rating for a Group 78 battery is somewhere between 50 - 70 Amp-hours. For the sake of demonstration, I'll be using the 80 Ah figure.

With the alarm off, the amount of energy that is drained from the battery is equal to 0.01 Amps multiplied by 8 hours which equals 0.08 Amp-hours.

With the alarm on, the amount of energy that is drained from the battery is equal to 0.50 Amps multiplied by 8 hours which equals 4.0 Amp-hours.

Neither is a huge amount of energy drained from the battery, as 50 Ah less 0.08 Ah is 49.02 Ah, which is essentially a fully charged battery. Now with the alarm on, the drain is equal to 50 Ah less 4.0 Ah which leaves 46 Ah of energy in battery, still a significant amount.

In my opinion, based on the current drains you measured, neither should result in a dead battery after 8 hours provided the alternator is working properly and the battery is fully charged.

Stop by an AutoZone, O'Reilly, Advance, or NAPA auto parts as all will test your electrical system in the car and let you know if the alternator is charging as it should and if the battery is indeed good and what it's state of charge is.
 

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Discussion Starter · #3 ·
Thank you for the math I wanted verification
the alternator Was checked at the shop down the street where they did my last alignment and I also verified it 14 volts coming from it
I know the battery is bad but walmart said its good
Wife called and we can go back up and swap out the battery under warranty like we tried yesterday they said it was good but when I charge it and it drops to 8 volts by morning unhooked from the vehicle
Wife called last night and told them thanks for ruining our trip for the holiday
 

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Yup, bad battery. I meant to ask how Walmart tested the battery? Really need to do a load test on a questionable battery. One can use a fancy conductivity tester, but they are not always accurate at declaring that a bad battery is bad. Putting a decent load on the battery while monitoring the battery voltage will let you know lickity-split if the battery is bad or not.

Hope you have a good Thanksgiving despite the bad battery and Walmart experience.
 

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Sounds like a conductivity tester. If not set up properly (entering temperature, battery type, CCA rating, etc.) they won't properly "evaluate" the battery being tested, and can cause false readings as you experienced.
 

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Discussion Starter · #7 ·
Wife said first reading failed then 2 good readings
We are getting a warrantee exchange tomorrow we tried yesterday but were told no borrowed a ride and now sitting at home making tv dinners for thanksgiving we were supposed to leave last night to head south
 

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2004 envoy xl 5.3
Test shows 0.01 amp draw with no alarm in 10 amp mode
Test shows 0.51 amp draw with alarm on in 10 amp mode

Battery keeps dying overnight with alarm on
Battery tested good at wally world
HOW were the "tests" done?

I've seen batteries discharge through the conductive slime on the outside of the battery case. The usual test for parasitic drain won't catch self-discharge across the semi-conductive case.

Put one voltmeter probe on the coorresponding battery terminal. + lead on the + terminal, for example. Take the other lead, and slowly "draw a circle" around the + terminal on the plastic of the case. Current is estimated by the amount of voltage registered--12+ volts is a huge drain, 3 volts is a small drain, but a CLEAN and DRY case should show less than one volt, perhaps "zero". The voltage reading may not be the same all around the circle--so the highest measured voltage "wins".

The fix is to wash the battery case with hot water and perhaps some detergent and baking soda. Be careful to NOT allow the water/detergent/baking soda to flow into the battery cells--some batteries are "sealed", but the "seal" is so poor that your cleaning water will contaminate the electrolyte. If you have to, use a rag dipped in the water/detergent/baking soda, to prevent the cleaner from drizzling into the cells.

DRY the battery case, and re-test.

Keep in mind that any acid on the outside of the battery case is acid that used to be part of the electrolyte, doing something useful. Batteries get topped-off with water, no-one ever replaces the lost acid.
 
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