Battery Issues

[SmokedTrail22]

The past 2 days I have gotten signs that the battery is dying: takes a second longer start, Auto Start/Stop is working randomly, and even had it mistake the gear I was in sitting at a red light. All I had to do is throw in Park and back into Drive and it was fine, but definitely not something that should be happening. So I got the main battery tested last night at Autozone and their test came back with 85% remaining life. I just replaced my head lights last week to some aftermarket LEDs and had to run a wire from the fuse box.

Is this going to be an aux battery issue or is there something I need to do regarding the fuse box?

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[Great Offender]

I don't know "when" you bought your JT but mine lasted a little more than 3 years. Replaced the main first and the aux about 2 weeks later. I never got a warning about my batteries and the Start/Stop almost never worked. In S. TX I would get a constant message letting me know the Start/Stop wasn't working because the A/C was on. In S. TX, really, too hot?
Surgery in January left it sitting in the driveway for about 2 weeks and it was dead. Never tried to charge the batteries because I had been there too many times.
I now have a permanent trickle charger under the hood with an outlet on the rear bumper to plug it in. I plug it in when I know it will be sitting. Start/Stop always works now.

This is my story so mileage with others may vary.

 

[berb]

It is probably just the aux battery. You'd be surprised at what that battery affects.

 

[Lost1wing]

The past 2 days I have gotten signs that the battery is dying: takes a second longer start, Auto Start/Stop is working randomly, and even had it mistake the gear I was in sitting at a red light. All I had to do is throw in Park and back into Drive and it was fine, but definitely not something that should be happening. So I got the main battery tested last night at Autozone and their test came back with 85% remaining life. I just replaced my head lights last week to some aftermarket LEDs and had to run a wire from the fuse box.

Is this going to be an aux battery issue or is there something I need to do regarding the fuse box?

Exactly how did the cashier at Autozone test just the main battery? The Aux and main are paralleled together. A load test couldn't have been done if nothing was disconnected. Perhaps the 85% is a capacity test? If so, they probably used the value for the main. With both batteries connected together your main would be less than 85%.

LEDs connected to the fuse box? Battery direct or ignition circuit? I'd question this since you have electrical gremlins and weak battery issues. Maybe post more details on the connections.

 

[SmokedTrail22]

Exactly how did the cashier at Autozone test just the main battery? The Aux and main are paralleled together. A load test couldn't have been done if nothing was disconnected. Perhaps the 85% is a capacity test? If so, they probably used the value for the main. With both batteries connected together your main would be less than 85%.

LEDs connected to the fuse box? Battery direct or ignition circuit? I'd question this since you have electrical gremlins and weak battery issues. Maybe post more details on the connections.

The Autozone guy just connected his device to the main battery. This was both of our first times dealing with the battery on the newer jeeps and I wasn't quite sure how to access or test the aux battery.

As for the LEDs, a wire came with the new headlights and ran it into the fuse box to have DRL capabilities. I used the slot F52 (cigar lighter) as recommended in the instructions.

 

[Lost1wing]

The Autozone guy just connected his device to the main battery. This was both of our first times dealing with the battery on the newer jeeps and I wasn't quite sure how to access or test the aux battery.

As for the LEDs, a wire came with the new headlights and ran it into the fuse box to have DRL capabilities. I used the slot F52 (cigar lighter) as recommended in the instructions.

Yes, f52 is an ignition circuit. That shouldn't be an issue.

Your batteries have not been tested. That was a waste of time at Autozone. Just read about batteries here! Read about charging your batteries here. Read about the precautions when disconnecting your batteries here.

Tons of info on this. Disregard misinformation on the Aux. Driving habits, prior abuse if preowned and improper disconnections/reconnections all affect battery life, ESS and other electrical issues.

 

[SmokedTrail22]

Yes, f52 is an ignition circuit. That shouldn't be an issue.

Your batteries have not been tested. That was a waste of time at Autozone. Just read about batteries here! Read about charging your batteries here. Read about the precautions when disconnecting your batteries here.

Tons of info on this. Disregard misinformation on the Aux. Driving habits, prior abuse if preowned and improper disconnections/reconnections all affect battery life, ESS and other electrical issues.

How do I properly test the battery then?

 

[Lost1wing]

Without knowing your skill level, it is hard to say what you should do. You already tapped into the fuse box, so that is a plus. After you learn a bit on your own, I would suggest isolating the batteries by disconnecting the two large cables at the main battery negative. One is your main ground going to the fender. The other is your Aux negative. By placing the red volt meter lead on the main positive and the black lead on the main battery, will tell you the main battery voltage. Placing the black lead on one of those cables you just removed will tell you the aux voltage. None of this really mean anything unless you see one at or about 12vdc and the other way different. A better way would be to connect an AGM charger in the same way I just described. After charging each battery separately, repeat the voltage test. You are looking for 12.8vdc or better, after letting the batteries rest a while after charging.

An even better option would be to remove both batteries( with caution) and take them in for a load test. Now the cashier at auto zone can do a better job at testing. The batteries would still need to be fully charged for testing.

There is another option, and that would be to pull the trigger and install two new batteries. You should not install just 1 battery leaving a potential problem installed. Of course the new batteries should be fully charged before installing. The batteries you get from the store are not fully charged. You may get lucky, but don't assume they are fully charged.

Pulling the trigger and installing 2 new batteries will suck if you end up with the same issues or introduce more issues, ie: fuse array problems or bad connections from the battery install.

Research!

 

[Lost1wing]

You can buy a hand held load tester that would give you an idea depending on the quality. I don't have a recommendation for a hand held load tester.

A VOM would be a great tool to keep in your Jeep btw.

An AGM charger would come in handy to.

A friend with these tools is even better.

 

[SmokedTrail22]

Without knowing your skill level, it is hard to say what you should do. You already tapped into the fuse box, so that is a plus. After you learn a bit on your own, I would suggest isolating the batteries by disconnecting the two large cables at the main battery negative. One is your main ground going to the fender. The other is your Aux negative. By placing the red volt meter lead on the main positive and the black lead on the main battery, will tell you the main battery voltage. Placing the black lead on one of those cables you just removed will tell you the aux voltage. None of this really mean anything unless you see one at or about 12vdc and the other way different. A better way would be to connect an AGM charger in the same way I just described. After charging each battery separately, repeat the voltage test. You are looking for 12.8vdc or better, after letting the batteries rest a while after charging.

An even better option would be to remove both batteries( with caution) and take them in for a load test. Now the cashier at auto zone can do a better job at testing. The batteries would still need to be fully charged for testing.

There is another option, and that would be to pull the trigger and install two new batteries. You should not install just 1 battery leaving a potential problem installed. Of course the new batteries should be fully charged before installing. The batteries you get from the store are not fully charged. You may get lucky, but don't assume they are fully charged.

Pulling the trigger and installing 2 new batteries will suck if you end up with the same issues or introduce more issues, ie: fuse array problems or bad connections from the battery install.

Research!

Really apprieciate the help!!

 

[tysongladiator]

I agree with Lost1wing for the troubleshooting. Spot on. I would like to also add that you check the CANBUS and physically check every connection. Not visually, physically.

I had an issue with the negative cable on my main battery once. Tight as tight can be and still having issues. I pulled on the terminal and it came right off the battery. I had to buy a shim in put in the terminal and problem solved. The dealership tried to tell my some garbage that I instantly knew was wrong. But, had I not pulled on that terminal, I would not have found that issue.

And it literally just had that same issue on my tractor a couple days ago. I shut the tractor off and it wouldn't crank. Checked the battery and another loose terminal. Guess I need to invest in battery post shims.

 

[SanTan38]

It’s simple, one failing battery will always cause the other to also fail. ALWAYS! So you need to change both the Aux and Main batteries at the same time. Never just replace one. Or you’ll just prolong the problems and get more frustrated trying to trouble shoot things. This is what the dealership said when they replaced my battery under warrantee, and also what I found out. (The hard way)

it’s just the way the ESS works. they both feed off each other. And similarly, they will try to draw off of the other one if it’s low. The Aux runs the electronics when the engine isn’t running and the main is for starting. So when the Aux fails, it will draw from the main. Then when the main starts to fail, it will draw from the aux when starting. Turning the run/start off doesn’t isolate the batteries trying to charge Themselves. This is how the dealership explained it to me.

 

[SmokedTrail22]

It’s simple, one failing battery will always cause the other to also fail. ALWAYS! So you need to change both the Aux and Main batteries at the same time. Never just replace one. Or you’ll just prolong the problems and get more frustrated trying to trouble shoot things. This is what the dealership said when they replaced my battery under warrantee, and also what I found out. (The hard way)

it’s just the way the ESS works. they both feed off each other. And similarly, they will try to draw off of the other one if it’s low. The Aux runs the electronics when the engine isn’t running and the main is for starting. So when the Aux fails, it will draw from the main. Then when the main starts to fail, it will draw from the aux when starting. Turning the run/start off doesn’t isolate the batteries trying to charge Themselves. This is how the dealership explained it to me.

I'm curious. I see people saying they do the aux delete. How is this beneficial?

 

[IamPro2A]

I'm curious. I see people saying they do the aux delete. How is this beneficial?

The sole purpose of the auxiliary battery is to maintain the voltage to the computers so the voltage drop caused by current draw from the ESS restarting doesn't cause glitches.
If you disable the ESS, there is no need for the aux battery.

 

[Chadnutz]

I removed the negative terminal for the aux battery at the main. No trouble. I'm not replacing two batteries every 3 years.

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