Parasitic draw..... maybe not?

[mpyusko]

I had an issue where my truck kept dying. Had Auto zone check it and it was bad. Had a bad cell In it. Got a new one. Still did it. The NEW battery they gave me had a bad cell too so I say get the battery checked out again

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I took a dead Alternator to Auto Zone 3 times and they kept telling me it was good. I paid a Chrysler tech $90 to prove to me it was bad. In the end I bought a new alternator and kept the core (get more money for scrap.... batteries too.). (If the alternator was good I was looking at a new PCM so after replacing every wire and connector..... because their high-tech machine said it was good.... i wanted to be certain so I took it to a dealer. Money well spent in my book.) Long story short... I used to work for Auto Zone, I'll never trust their test results..... except when the lady said my 3y/o battery had a 2.5% capacity at full-charge so they'd replace it for free.

But that goes back to my problem. When I bought the truck it had a 6m/o AC Delco battery in it. DEAD. Then I swapped in the 3y/o battery from my Jeep. DEAD. Now the brand new one is running down and if I don't get this figured out it will be DEAD too.

PS.... I just bought the truck in March.

 

[mpyusko]

Voltage didn't drop enough on the battery when I tried cranking it. Gotta dig deeper.

 

[Ruger_556]

I have a spare 1000CA battery I keep in the garage on float, but when I pack it up to take it with me I can only get 2 jumpstarts out of it, against a dead battery in the truck... the 454 takes a lot of juice to crank.)

Ideas?

Even a 454 shouldn't start that hard...

 

[mpyusko]

Batteries always try to equalize when connected. So when to have a 'low' battery and try to jumpstart it, it doesn't take much to do it. But when you have a 'dead' battery and are trying to jumpstart it, it acts like a black hole for Amps. It instantly reduces how much you have available to start the engine. Think about it, I assumed you've jumpstarted a few cars. You can always tell how dead or solid of a connection you have by listening to your engine when you connect your cables. If the rpm drops slightly and the alternator gets loud, you know the other battery is pretty well drained because your vehicle is now trying to charge it. If you only hear it drop a little and pretty much nothing from the alternator, then the lights and radio were probably still working in the other car, but the battery didn't have enough to crank it over.

So when you try and Jumpstart with a static battery (one that isn't being boosted by a car) and idle 3 blocks across town with the kids, you haven't given it enough for the truck to charge to make it any easier for the one sitting on the floor of you passenger seat. Keep in mind that you vehicle actually runs off the battery, your alternator just keeps it charged up.

 

[mpyusko]

I just spent the 2.5 hours chauffeuring my wife around running errands. While there was some actual speed involved, the majority was spent idling in a parking space while the kids slept. When I got home and finally shut it off, i check the voltage after letting the headlights sit on for a minute.... 12.73 so it is obviously fully charged. I did a tracklog and it shows the Alternator stay up the entire time. No intermittent dips which is what I was concerned might be happening.

 

[mpyusko]

Just sat exactly 36 hours. Down to 10.2V

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[Chevyguy78]

Your battery can show 12.75volts and have no CCA's. Just because you have voltage doesn't mean your battery is good. Have I your battery tested. It sounds like its shot. I worked at Exide battery and we always saw batteries come back with voltage and no CCA's

 

[mpyusko]

Your battery can show 12.75volts and have no CCA's. Just because you have voltage doesn't mean your battery is good. Have I your battery tested. It sounds like its shot. I worked at Exide battery and we always saw batteries come back with voltage and no CCA's

I went to Autozone today and they did two consecutive tests on the battery. It said "good", but capacity was reduced by 10% after and a very slow recovery. We both agreed that should not be the case for a battery made 3 months ago. He swapped it out no problem and even installed it for me. Then we did the same 2x test on the brand new battery and it jumped back up fine. He asked me about the alternator. I said"well, I jump-started the thing this morning and now you are telling me your tester reads the battery as fully charged. Call it a hunch, but I would say it's a safe bet the Alternator is working." We did however hook a multimeter up to the new battery and cranked the truck for a normal (nothing disabled) start. The voltage dipped down to the mid 10s (hard to be sure with a digital) which tells me a starter might come due this winter. I seriously hope this fixes the problem because I can't find another culprit anywhere.

To clarify, the battery was at that "low enough to not start but high enough where everything else works" point. I was running late for a Dr's appointment so I didn't spend the time to analyze voltages and plot mathematical parabolas. I just plugged the spare into the cigarette lighter and took off.