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Battery Drain - not starting


ndaddy

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Joined
Jul 7, 2020
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19
Location
Maryland
Hola friends, I am back again with a new issue on my 06 that ive owned for 6 weeks now. My new PCM is supposed to arrive Monday; I hope / pray / optimistically wait for that to fix the cold transmission lurch issue.

I have not driven my car in about 6 days as I did not want the car to do too much jolting for 1st-2nd gear. However its been so hot, so I reset the battery to temporarily clear the issue and drove it a few times.

I noticed last night when walking by the car that my radio clock was on. The key has 4-5 positions, if 0 were car off and 3 were ignition, -1 for some reason is the battery remains on. I grabbed my keys and turned the car fully off right away. I turned the ignition on and drove it around for a few minutes, happy that it still turned on. I did not happen to look at the voltage on dash at time. It had a harder start this AM; it had a hard start again in PM and I drove it a few miles to the store when I realized the voltage on the dash was between the left/mid dot and 14, when in the past it was ALWAYS slightly above 14. When I pressed the gas, it would go back to 14.2, when i slowed down or idled, it would drop lower again.

When I tried to leave store, it wouldnt start. It cranked and cranked but just wouldnt start. I got a jump, and it started instantly.

Which leaves me at my issue / question. I drove it around for about 20 minutes to see if maybe the battery needed a charge. It continued to do the same fluctuation for a majority of the drive, except when i drove home and let it stall for another 5 mins, it finally remained on ~14.2; turned it off, and turned it on no issues and stayed at 14.2. I will check again later and am praying it just needed a charge after being depleted, but -

Do you think there is any correlation between the radio being on for 5-6 days and my car not drawing power to start (after already starting 4 other times)? Or do you think there is a new issue where there is a short somewhere in the system that arose from elsewhere?

sadly really regret this purchase, I had the car pre-inspected and STILL have put in over 25% of car's price into repairs, and issues remain.
 

Jerry Bransford

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You've got a dead or nearly dead battery. Starting the engine took what little life it had left. The battery needs to sit on a battery charger overnight, it's dead enough that a couple hours on a charger won't do it.

And don't just jump start it thinking you can drive it around to charge the battery, those days are long gone. The alternator requires a good solid 12 volts from the battery to power its exciter circuit so when the battery is dead or nearly-dead, the alternator won't put out enough power to keep the engine running for long, let alone also charge the battery. Modern alternators pretty much all now require a solid 12v from the battery before they can produce power.
 
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ndaddy

ndaddy

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Joined
Jul 7, 2020
Messages
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Location
Maryland
You've got a dead or nearly dead battery. Starting the engine took what little life it had left. The battery needs to sit on a battery charger overnight, it's dead enough that a couple hours on a charger won't do it.

And don't just jump start it thinking you can drive it around to charge the battery, those days are long gone. The alternator requires a good solid 12 volts from the battery to power its exciter circuit so when the battery is dead or nearly-dead, the alternator won't put out enough power to keep the engine running for long, let alone also charge the battery. Modern alternators pretty much all now require a solid 12v from the battery before they can produce power.
Per usual, a huge help. Thanks Jerry.
 
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Jerry Bransford

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If you have any more battery issues, take the battery to a battery specialty shop and ask them to perform a "load test" on it. That's the only test that will show its true health. It places a heavy load on the battery, like starting the engine does, and it measures the voltage as that is happening. If the voltage drops off too much during the load test the battery is toast.
 
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ndaddy

ndaddy

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Joined
Jul 7, 2020
Messages
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Location
Maryland
If you have any more battery issues, take the battery to a battery specialty shop and ask them to perform a "load test" on it. That's the only test that will show its true health. It places a heavy load on the battery, like starting the engine does, and it measures the voltage as that is happening. If the voltage drops off too much during the load test the battery is toast.
Mark @ wrangler fix told me I should probably get a new battery anyway when using the new PCM since its 2 years old. I guess ill probably do it regardless
 
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Jerry Bransford

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Mark @ wrangler fix told me I should probably get a new battery anyway when using the new PCM since its 2 years old. I guess ill probably do it regardless
If you do at least have the battery retailer do a load test just so you'll know. An AGM style battery would be a good choice, they are built more ruggedly than a standard wet-cell battery is to resist the standard jolts and shocks encountered on offroad trails. I'd avoid any of Optima's batteries which no longer have a good reputation after their manufacturing was moved to Mexico several years ago.
 
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