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Discussion Starter · #1 ·
... Whether your battery, alternator or regulator is the bad guy?

I just had my battery tested.
They are telling me that it is bad. (3 1/2 years old, yeah, I do believe it's time for a. Ew battery.)

I don't mind replacing the battery.
I just want to know if that's the only thing wrong with it.

I remember pulling up into my driveway a while back.
I was just about to put the shift lever into PARK, when all of the sudden, the engine idled low, then quit on me.

My jeep was trying to tell me that there was a problem, but I wasn't listening then.

I will replace the battery, because it is dead.
But now I'm wondering could I also have a bad alternator or regulator.

What would be the reason for my engine to run fine, then idle really low, then die?
 

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The regulator is built in to the alternator. A low battery or low output from the alternator can cause all kinds of seemingly bizarre and you would think unrelated problems, a bad battery or alternator can cause real havoc in all of your systems from gauges to hvac to ignition.

You can buy a cheap multi-meter at just about any parts store or Harbor Freight, start the Jeep, put the black on a metal surface and the red on the positive battery post, if it's reading anywhere around 14v, your alternator is good, if it's reading less than 13v, then put the red lead on the large bolt under the black rubber on the back of the alternator, if that is around 14v, you have a bad cable, if it's under 13v, you have a bad alternator. Then shut off the Jeep, place the black lead on the negative post and the red lead on the positive post, if it's under 12v, you have a bad battery, if it's over 12 but under 13v, the battery is questionable, if it's over 13v, the battery is most likely good, wait a couple hours and check the battery again, a few hours later if should still be around the 13v area (+/-.5).
 

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The regulator is built in to the alternator. A low battery or low output from the alternator can cause all kinds of seemingly bizarre and you would think unrelated problems, a bad battery or alternator can cause real havoc in all of your systems from gauges to hvac to ignition.

You can buy a cheap multi-meter at just about any parts store or Harbor Freight, start the Jeep, put the black on a metal surface and the red on the positive battery post, if it's reading anywhere around 14v, your alternator is good, if it's reading less than 13v, then put the red lead on the large bolt under the black rubber on the back of the alternator, if that is around 14v, you have a bad cable, if it's under 13v, you have a bad alternator. Then shut off the Jeep, place the black lead on the negative post and the red lead on the positive post, if it's under 12v, you have a bad battery, if it's over 12 but under 13v, the battery is questionable, if it's over 13v, the battery is most likely good, wait a couple hours and check the battery again, a few hours later if should still be around the 13v area (+/-.5).
Just FYI...All quite true, except the output voltage of the alternator is regulated not by a regulator built in to the alternator, but by regulator circuitry built into the pcm.
 

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Discussion Starter · #5 ·
have you fixed the problem yet
Not yet.
The guy at Wally-Mart told me that my battery was bad.
Of course, this is the battery that was in the jeep when I bought it, and it is from Wal-Mart, so of course, he'll tell me it's bad, whether it is or isn't, hoping I'll buy another one from him.

I don't mind paying for another battery. Just don't want to fork out the money, just to find out that it wasn't a battery problem.

I will try the ideas that one of the other members suggested (I've got to dig out my meter.)

I'll keep y'all posted.
 

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If the battery is 3 1/2 years old then it is almost 90% just the battery, especially if it's a cheap walmart battery. To many times have I seen alternators and starters replaced due to a battery issues. Why do you think most batteries only come with a 30month/3yr replacement? Because they don't usually last much longer then that. Other wise they would be 5yr etc. :p

Due yourself a favour and by a decent brand battery. For the extra $20-50 it's defiantly worth it IMO.
 

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My bet is the battery is toast, but you can know for sure by a competent experienced battery tech performing a good load test on the battery. And not all know how to perform a load test. A new tech at my local battery shop I had never seen before recently told me after performing a cursory load test that my Toyota battery was fine even though I knew from experience that it wasn't. I waited for the other guy I knew to conduct a second load test but performed correctly... it showed the battery to be toast.

A load tester is a specialized device that can put a major test load on the battery and measure the battery's ability to put out power while heavily loaded. A good tech will hold the load on the battery for a period of time, not just a few seconds. A normal volt meter won't do for this test.

And yes, the TJ alternator's voltage regulator is located inside the PCM (engine computer) mounted on the fire wall, it's not in the alternator. It rarely goes bad. :)
 

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Most shops including walmart I would suspect(at least here) use midtronic hand held battery testers which are pretty accurate, not a %100 but do a pretty good job. And most shops will test your battery for free as well. If they do get the print out from the tester and it will confirm if it is good bad or just needs a good charge.

Also another thought that jut popped in to my head is if you do a lot of short trips and or have accessories etc. then your battery never really has time to fully get charged so overtime it will give slowly discharge with out ever fully getting charged and give the same symptoms of a dead battery but the midtronic will know this. My electrical professor lives 2kms from the college and he says he had to throw the charger on his battery atleast once every 10months or so for the exact reason I just explained.
 

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Discussion Starter · #9 ·
... the TJ alternator's voltage regulator is located inside the PCM (engine computer) mounted on the fire wall, it's not in the alternator. It rarely goes bad. :)
Which one rarely goes bad?
The regulator or the alternator?
 

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Don't trust Walmart people with car stuff. 99% of the stuff they say is BS. Go to a place like Autozone where the person must know about car stuff before getting hired.
 

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Most auto parts places like AZ can load test the battery and also check the alternator. Unless your walmart battery is pro-rated and you get a decent discount for the trade in, I would buy elsewhere. Go with a Diehard battery if possible. More than likely a bad battery that can't hold a charge from a good alternator.
 

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Don't trust Walmart people with car stuff. 99% of the stuff they say is BS. Go to a place like Autozone where the person must know about car stuff before getting hired.
:rofl: You don't really believe that do you? I needed desperately needed a pinion nut for my rear axle and (literally) not a single employee in my local AutoZone had a clue what a pinion shaft or pinion nut was. Most AutoZone people I encounter are clueless if they can't find the answer spelled out for them on their computer.
 

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Don't trust Walmart people with car stuff. 99% of the stuff they say is BS. Go to a place like Autozone where the person must know about car stuff before getting hired.
Yea I've got a bone to pick with those turds at both locations,I'm just another dumb kid that doesn't know what part he needs when it comes to autozone staff. I'd rather see the goodwill Easter seals open up a parts store, they know what's up, and actually try.

As far as Wally World this is why you stay clear of them. And no it wasn't balanced.
 

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Discussion Starter · #16 ·
... start the Jeep, put the black on a metal surface and the red on the positive battery post, if it's reading anywhere around 14v, your alternator is good, if it's reading less than 13v, then put the red lead on the large bolt under the black rubber on the back of the alternator, if that is around 14v, you have a bad cable, if it's under 13v, you have a bad alternator. Then shut off the Jeep, place the black lead on the negative post and the red lead on the positive post, if it's under 12v, you have a bad battery, if it's over 12 but under 13v, the battery is questionable, if it's over 13v, the battery is most likely good, wait a couple hours and check the battery again, a few hours later if should still be around the 13v area (+/-.5).
After I got my battery back from the auto parts store, but before I put the battery back into my jeep, measuring across the battery posts (fully charged, supposedly), I got a reading of 13.60 volts.

Even after the auto parts store recharged my battery, it took a few times for me to jump start it with another vehicle. Once I did get it started, I proceeding to follow your instructions for testing the battery & alternator.

With the engine running & the positive lead on the positive post of the battery, & the negative lead on a grounding bolt, my readings were around 13.90 to 13.95 volts.

With the engine running & the positive lead on the bolt that is on the backside of the alternator, & the negative lead on a grounding bolt, I got a constant reading of between 13.94 to 14.00 volts.

At this point, I really believe that the problem is my battery, and hopefully, only my battery.
 

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Discussion Starter · #17 ·
****** UPDATE ****** Ok. I just now checked the voltage of my battery, now that it has been sitting for a while since I jump-started it earlier tonight.

The battery now has a reading of 10.73 volts. This is with the jeep NOT running.

Looks like I'll be getting a Die Hard battery.

A few years ago, I replaced my truck battery with a Die Hard. Never had a problem with it.


Thank you, to everyone. This forum is awesome. Plenty of knowledge, & knowledgable people always willing to help.

Thanks, again.
 

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Yea I've got a bone to pick with those turds at both locations,I'm just another dumb kid that doesn't know what part he needs when it comes to autozone staff. I'd rather see the goodwill Easter seals open up a parts store, they know what's up, and actually try. As far as Wally World this is why you stay clear of them. And no it wasn't balanced.
I on the other hand will only go to Walmart to balance my tires. They put all the weights on the inside. For me. Asked what I preferred. And they are the only ones that never fed it up. I had them rebalance new tires bought else where. And had my mtrs I bought on the internet mounted and balanced there. And my wife's ram. With me they have done great 5 out of 5 times over the years and different states. I would highly recommend them.
 

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I on the other hand will only go to Walmart to balance my tires. They put all the weights on the inside. For me. Asked what I preferred. And they are the only ones that never fed it up. I had them rebalance new tires bought else where. And had my mtrs I bought on the internet mounted and balanced there. And my wife's ram. With me they have done great 5 out of 5 times over the years and different states. I would highly recommend them.
You sir got lucky.. This is my third set on two vehicles. And they say it's supposed to be like that. I told them the high school shop across the way does it cleaner (same buster and balancer I would know, I used it a lot back in the day). And they told me to take it over there. I just liked the cheap tire prices and stash of gift cards I had to burn.
 
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