Aux battery delete.

[aaron.1]

Hi there. I own a 2018 wrangler sport. For about the last month and a half I’ve been having non stop issue with the batteries. My stop/ start light came on notifying me that it will no longer be working. My Jeep need to be jumped EVERY morning! Once the Jeep is started in the morning it starts just fine the rest of the day, I work in the medical field and work 12 hour shifts and even after my 12-13 hour days it starts right up after work. I replaced the auxiliary battery and found out that since the aux battery was draining the main battery. I then replaced the main battery and went for a drive. My battery light came on while I was driving. I saw that the volts were dropping very fast and a message came on staying “STOP SAFELY VEHICLE WILL SHUT OFF SOON/SERVICE STOP START”. I pulled off into a parking lot and tested the alternator and found out it was bad. I replaced the alternator. So I have a brand new alternator, brand new main and aux battery and it’s still needing to be jumped every morning. I saw that if you remove the F42 fuse and the negative terminal that it would bypass the aux battery. I did that and still having the same issues of the Jeep needing to be jumped. I’ve taken it to a Jeep dealer and another shop that specializes in Jeeps and they don’t know what the issue is. Can someone please help or explain what they think is wrong. Thank you.

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[AndySpill]

Confirm that none of your high amp fuses have been blown. This first link below provides a video where they are located, if you aren't familiar, and the subsequent link provides you with your choice of videos (pick one) on how, using a multimeter, to perform a continuity test on these fuses if you aren't familiar, to see if any of those fuses have been blown.



https://www.youtube.com/results?search_query=multimeter+continuity+test

If one or more fuses are blown in this array this could affect your presumptively new and working alternator from effecting a charge to the batteries, particularly the 3rd one in counting from the front of the vehicle back (N3). You do not need to replace the entire PDC (Power Distribution Center) to remedy this, as discussed in the first video, but if at least one fuse is blown in the array, the entire (far more affordable than the entire PDC) array will require replacement.

The array comes in two different parts numbers, depending on whether you have the tow package or not, as follows:

https://www.jlwranglerforums.com/forum/threads/alert-high-amp-fuse-array-related.65085/

 

[aaron.1]

Confirm that none of your high amp fuses have been blown. This first link below provides a video where they are located, if you aren't familiar, and the subsequent link provides you with your choice of videos (pick one) on how, using a multimeter, to perform a continuity test on these fuses if you aren't familiar, to see if any of those fuses have been blown.



https://www.youtube.com/results?search_query=multimeter+continuity+test

If one or more fuses are blown in this array this could affect your presumptively new and working alternator from effecting a charge to the batteries, particularly the 3rd one it counting from the front of the vehicle back (N3). You do not need to replace the entire PDC (Power Distribution Center) to remedy this, as discussed in the first video, but if at least one fuse is blown in the array, the entire (far more affordable than the entire PDC) array will require replacement.

The array comes in two different parts numbers, depending on whether you have the tow package or not, as follows:

https://www.jlwranglerforums.com/forum/threads/alert-high-amp-fuse-array-related.65085/

thank you for responding! I did change the whole fuse anreay and it worked for the first few days. No issues of needing to be jumped and then after day 2 I had to go back to jumping it every morning. I don’t know if I should do a parasitic draw test and see if there’s a draw somewhere.

 

[AndySpill]

thank you for responding! I did change the whole fuse anreay and it worked for the first few days. No issues of needing to be jumped and then after day 2 I had to go back to jumping it every morning. I don’t know if I should do a parasitic draw test and see if there’s a draw somewhere.

I'd consider doing business with another dealer's service department.

Is the negative cable leading from the Aux battery, if still under the hood, tapped up well at the end normally connected to the main battery, that you disconnected?

 

[aaron.1]

I'd consider doing business with another dealer's service department.

Is the negative cable leading from the Aux battery, if still under the hood, tapped up well at the end normally connected to the main battery, that you disconnected?

Yeah I think I need to get another opinion, and it was connected to the main batter and everything I’ve read says to disconnect the negative terminal from the main battery which I did and taped it off well with electrical tape and zip tied it to where it wouldn’t be able touch any metal. From what I’ve read everyone that has done that said it works but not for me it’s still needing to be jumped.

 

[dchemphill1]

It is possible you got a bad battery. That happens more often than it should. Before you have to jump what is the battery voltage? Also check battery connections and grounding connection.

 

[aaron.1]

It is possible you got a bad battery. That happens more often than it should. Before you have to jump what is the battery voltage? Also check battery connections and grounding connection.

Whenever the Jeep is running the volts sit around 13.8- 14.2. I’ve thought about as battery, it’s weird because sometimes the volts are fine and reading 13.8-14.2 but then time where I accelerate and the volts drop to 12.7 and when I let off the gas’s the volts go back up. None of it makes sense to me as to what is going on.

 

[Jeffy56]

It's possible for a bad alternator as well. If you have a voltmeter you can verify engine off battery voltage then engine running voltage. Might be able to see this in the dash display. 12.2 +/- or higher off, 14.2 +/- running. Those numbers are approximate and will vary depending on battery charge.

 

[Jeffy56]

Whenever the Jeep is running the volts sit around 13.8- 14.2. I’ve thought about as battery, it’s weird because sometimes the volts are fine and reading 13.8-14.2 but then time where I accelerate and the volts drop to 12.7 and when I let off the gas’s the volts go back up. None of it makes sense to me as to what is going on.

The Jeep has a "smart" alternator and will output more at cruise or coast. Doesn't seem like a bad alternator.

 

[aaron.1]

It's possible for a bad alternator as well. If you have a voltmeter you can verify engine off battery voltage then engine running voltage. Might be able to see this in the dash display. 12.2 +/- or higher off, 14.2 +/- running. Those numbers are approximate and will vary depending on battery charge.

I have a brand new alternator that I put in I want to say around 3 weeks ago so it’s very new. I can test it again and see if that’s the issue.

 

[aaron.1]

The Jeep has a "smart" alternator and will output more at cruise or coast.

Ohh yeah I’ve heard of that, they are coming up with to many “smart” options.

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