It's not the Battery

Fiance's 2018 Jeep Cherokee wouldn't start on Sunday, wouldn't even crank. I went and got my jump pack and hooked it up and it started up right away, but once it started, all the lights on the dash and everywhere started flashing on and off. Once I removed the jump pack, it died again. Tried to crank without the jump pack, nothing, no lights at all.

Attached the jump pack again and it started, but again flashed everything and shut off when I removed it.

Went and got jumper cables, started with jumper cables, let it charge for a while, when I pulled them off it died. Jumped again but held the RPMs up at like 4k removed jumper cables, stayed running, then RPMs dropped and it died.

The dealer is trying to say it's the battery, that it was so dead it wouldn't even hold a charge. I know it's not the battery, it has to be the alternator, or a bad ground somewhere but they are sticking to their guns. I plan to go to the dealer and remove the positive cable on the battery and show them that's it's going to die.

My worry is they won't care and will send her home like this and once the battery finally does die they will charge her again.

Some explanation, she bought the jeep before we met and bought the extended warranty from the dealer. I would have advised against it but I also wouldn't have let her buy a Chrysler... anyway, that's water under the bridge. Since she bought the warranty there, if they do they work it's free, if it's anywhere else it's a $200 deductible.

but get this, since a battery is consumable, it's no covered by warranty and also would charge her an additional $170 for the diagnostics.

Is my plan at the dealer going to backfire? how can I show these guys the problem is more than just the battery?

 

I'm confused... first off, why do you "know" it's not the battery? It's entirely possible that the battery has a shorted cell and it won't hold/can't take a charge. Step one is to take the battery out, and take it to an auto parts store; they all have testers that will give you a battery 'health' report. If the battery is good, then check the alternator; a rough and ready check is simply to check voltage, using a DVOM at the battery terminals; if it's >13.5, then it's likely your alternator is alternating; if it's below that, it may be dead/dying, and again most auto parts stores can bench test it for you.

Out of curiosity, what would you expect to happen to a gasoline engine when you remove a battery cable?

 

Buy a new battery at Wally Mart

 

The first problem is that it’s a Jeep...

Right, @ColoradoTJ?

 

Dead batteries can produce the exact same symptoms that you describe. For fun, swap in your truck battery for a minute and see if it still sputters.

 

I'm agreeing that the alternator is part of the issue. However, a good battery should still keep the vehicle running for a little bit, especially after charging. I'm willing to bet both need replacing. It would be worth testing the alternator.

 

A deeply discharged battery is chemically depleted. They won't charge or hold a charge. If it does charge, the life of the battery is severely shortened.

The Jump pack was acting like the car battery.


I just went through this with the wife's '19 CR-V. It slept in the garage for about 2.5 months. Battery was so depleted by parasitic draw that it wouldn't light the dashboard. Jumped it, drove it at Highway speeds for more than 1 hour. Shut it off in the driveway.......wouldn't restart or light the dashboard. Battery was a 40+ lb anchor. New battery and drive it weekly, no more trouble.


Get a new battery. Be done with it. For the $170 diagnostic, you could have a new battery.

 

Yeah I understand I could have gotten a new battery for the cost of the diagnostic, but I was assuming it was the alternator AND battery.

If it's just a problem with the battery, after I jumped it, shouldn't it have stayed running?

The age old test to see if the alternator is bad has always even to disconnect the battery after starting it. if it stalls, bad alternator.

 

If you pull off the battery cable and the alternator is producing the right amount of voltage it should stay running. if your alternator isn't producing enough power to keep the vehicle running you'll always end up with a dead battery.

 

That it stays running, duh! But you’re not here to help, are you? I digress...

OP, it would seem that both the alternator and battery are bad, assuming you have ruled out faulty wiring. If it was just the battery, it would have stayed running after pulling the jump pack. Kinda sucks the dealer is taking that stance but not surprising. Extended warranties really only make money if they are not being used or coverage is denied. Don’t Jeep’s have an indicator light for a no charge condition as well? Tacoma’s do. Change the battery at Costco yourself, and then let them deal with the rest.

 

It’s not great to do for electronics on modern vehicles and you can test the same by measuring with a voltage meter. But you’re not wrong

 

Guess you don't like you alternator much.

 

Clean the battery cables try it again. You know like take they off clean and try again.

 

Thanks for the sanity check man, I really do appreciate the input.

The only positive experience I've ever had with a dealer has been the place I bought my taco, they gave me the best price I've seen in the country and have been excellent with both warranty claims I had while I was still under 36k miles.

I'm hoping when I go and pick up her vehicle I'll be able to talk to someone that at least understands how the charging system SHOULD work. I just don't want her to get stuck with a dead car, fortunately I was with her this time.

 

Buy a $5 multimeter and you can check the battery voltage and the alternator in 2 minutes

 

Wife owned the same make and model just a 2016 and had similar issues. If I remember correctly, Jeep, starting in 2014 began sourcing their batteries from a different manufacturer and they’ve had issues ever since. Try a new battery.

 

In 1975, sure... now? Not so much. Regardless, it's VERY bad for your electrical system on a modern vehicle, and would in no way prove, or disprove the battery as a culprit. This is a very simple trouble-shooting scenario, and half an hour of YouTube and <$20 worth of tools and you can do everything yourself.

 

I’ve got a multimeter, that’s not the problem, I just don’t believe then when they said it’d just the battery. I’m going to check the voltage on the battery when I get home and see what it’s at then check after we drive it for a bit.

As I expected they didn’t check the alternator they only did a load test on the battery determined that was the only issue and sent her on her way.

 

the service rep also told me they checked the entire “charging system” but only the battery load test was on the invoice, no info on any other test performed... not even alternator voltage.