Bad alternator or just dead battery?

DropTopDon

DropTopDon

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Was leaving the kroger’s when I got in my Jeep and it wouldn’t start or crank. I checked starter and battery connections and everything seemed to be in order. Ignition lights turned on once and then didn’t turn on again. I got a friend to come give me a jump but even with that there was no crank at all. Does this mean my alternator has gone bad? Jeep is currently just stranded in the parking lot.
 
More than likely your battery is just toast. A really dead battery will suck so much juice out of a jump start battery that even a good jump start battery won't always do the job. Cheap thin jumper cables can exacerbate the problem.

And a dead battery won't be rechargeable by the alternator. That's because the alternator's exciter field is powered by 12 volts from the battery. When the battery is dead enough the alternator won't be able to put a charge out.

Have the battery "load tested" by a battery shop that knows how to properly conduct a load test. A load test is the ONLY way to know the battery's true health and if it's bad or not. Odds are good it is bad.

But even a load test requires the battery be charged up as much as it can be. If you have a battery charger, not a trickle charger, put that on the battery over night. A few hours won't do it.
 
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Jerry Bransford said:
More than likely your battery is just toast. A really dead battery will suck so much juice out of a jump start battery that even a good jump start battery won't always do the job. Cheap thin jumper cables can exacerbate the problem.

And a dead battery won't be rechargeable by the alternator. That's because the alternator's exciter field is powered by 12 volts from the battery. When the battery is dead enough the alternator won't be able to put a charge out.

Have the battery "load tested" by a battery shop that knows how to properly conduct a load test. A load test is the ONLY way to know the battery's true health and if it's bad or not. Odds are good it is bad.

But even a load test requires the battery be charged up as much as it can be. If you have a battery charger, not a trickle charger, put that on the battery over night. A few hours won't do it.
Click to expand...
Thanks for the advice. I’ll troubleshoot that tomorrow.
 
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On the off chance the battery checks out, go through and clean the hell out of all pos and ground cable ends. Be sure they are to clean metal and the bolts are free of rust too. And if possible double check with a multimeter that they all have minimal resistance in them. Cables have broken inside the plastic outer covering to the point they don't allow enough power to reach the starter or ground.
 
The battery checked out and had 12.6 volts. I checked my starter and it looked fine too. I rammed the key into the ignition and pushed it with a little bit of excessive force and my jeep turned on so I could bring it home. With the starter and battery eliminated I replaced the ignition switch. The problem is still there and now when I turn the key to the lock position it makes a repetitive clicking noise. All the odometer needles bounce up and down whenever i attempt to turn it on again. What else could be the reason?
 

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You really need to test the cranking amps of said battery and test the alternator too.

Let me tell you something with jumping. Battery cables today suck. They sell garbage cables everywhere and they're complete trash.

They're cheap. In this day of people wanting everything for pennies they sell them alright...but junk. Total junk.

The expensive ones with a real heavy duty clamp are ok. But they're more money which today goes against all thinking.

When was your battery mfg? (Date)

Here is a battery not that old.

20210128_153203.jpg

The voltage looks ok...right?
But the CCA is supposed to be 800.
This isn't the worst of examples but as you see the volts are ok but not the CCA for the Battery rating.

You can't rely just on a multimeter at the post only.

Using a mm to check alternator is fine.
 
Jerry Bransford said:
That sounds like a broken ignition actuator pin that sits behind the ignition switch. They go bad often enough that I carry a spare with me in my parts box.

https://www.amazon.com/gp/product/B004BYX8W8/?tag=wranglerorg-20
Click to expand...
That’s what I thought, I visually examined the actuator pin and it looked okay, there wasn’t anything visibly broken that I could see. Is the clicking during the Locl position
Rubicon88 said:
You really need to test the cranking amps of said battery and test the alternator too.

Let me tell you something with jumping. Battery cables today suck. They sell garbage cables everywhere and they're complete trash.

They're cheap. In this day of people wanting everything for pennies they sell them alright...but junk. Total junk.

The expensive ones with a real heavy duty clamp are ok. But they're more money which today goes against all thinking.

When was your battery mfg? (Date)

Here is a battery not that old.

View attachment 221692
The voltage looks ok...right?
But the CCA is supposed to be 800.
This isn't the worst of examples but as you see the volts are ok but not the CCA for the Battery rating.

You can't rely just on a multimeter at the post only.

Using a mm to check alternator is fine.
Click to expand...
My cranking amps were in the 800’s. If my battery is fine should i still check the alternator?
 
Jerry Bransford said:
That sounds like a broken ignition actuator pin that sits behind the ignition switch. They go bad often enough that I carry a spare with me in my parts box.

https://www.amazon.com/gp/product/B004BYX8W8/?tag=wranglerorg-20
Click to expand...
I visibly examined the actuator pin when I had the ignition switch out and the metal pin was still intact and looked okay to me. Is the clicking noise it is making while in the lock position the actuator pin? Would you recommend I just get install a new actuator pin as well just to see if that fixes it?
 
Haaris Khan said:
That’s what I thought, I visually examined the actuator pin and it looked okay, there wasn’t anything visibly broken that I could see. Is the clicking during the Locl position

My cranking amps were in the 800’s. If my battery is fine should i still check the alternator?
Click to expand...
How old is it? A new battery will recoup itself sitting over night even if your alternator killed it. If it's an older battery then your alternator im sure is fine.

Now the second thing...

I can't stress to you enough how finicky battery connections can be.

We get a lot of "my battery is bad" customers only to show them the connection is shit.

Now you very well might have another issue but it's worth noting the importance of those connections as well.
 
I dunno, it's really hard to know without being there to see it. That symptom certainly can be caused by a broken actuator pin but if it's not broken, it has to be something else. That by pushing the key in harder caused the engine to start sure makes me think it has to be the actuator pin but...
 
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Rubicon88 said:
How old is it? A new battery will recoup itself sitting over night even if your alternator killed it. If it's an older battery then your alternator im sure is fine.

Now the second thing...

I can't stress to you enough how finicky battery connections can be.

We get a lot of "my battery is bad" customers only to show them the connection is shit.

Now you very well might have another issue but it's worth noting the importance of those connections as well.
Click to expand...
The battery is about two to three years old. I took the battery out to get it load tested and when I was putting it back in I made a small effort to clean up excess corrosion but it was nothing too detailed.
 
Update: Got my Jeep started after I disconnected everything that has a connection to the battery and cleaned all connections. Best feeling ever to hear it turn on again. If it happens again I'll know what to expect.
 
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