Replacing Stock Battery(and Bypassing the Aux Battery) Easiest Solution

[DaltonGang]

It decided to quit on me. seems a bit premature but had it tested and I was driving around with a battery at 11.6V before I through a new one in.

I also want to add that disconnecting the AUX negative and pulling the F42 fuse has solved my A! light. If anyone cares the codes it was throwing while it was on were P00FD & U0010 (Medium Speed CAN Comm Bus)

Did you have the IBS(Intelligent Battery Sensor) checked??

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[AlphaWrangler]

Did you have the IBS(Intelligent Battery Sensor) checked??

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I did not. does that have something to do with the alternator? Or aux battery?

 

[DaltonGang]

I did not. does that have something to do with the alternator? Or aux battery?

Yes, it regulates the output of the alternator. It can make the Aux Battery look bad, or make the Alternator look like it is defective. Mine crapped out, and was replaced, a year or so, into buying the jeep. All signs pointed towards the.Aux Batt then.

 

[AlphaWrangler]

Yes, it regulates the output of the alternator. It can make the Aux Battery look bad, or make the Alternator look like it is defective. Mine crapped out, and was replaced, a year or so, into buying the jeep. All signs pointed towards the.Aux Batt then.

interesting. At the moment the alternator is function and I still have the original aux battery. I don’t think there is any chance that it isn’t more than a brick. Either way hoping I didn’t just toss a good alternator

 

[Jebiruph]

Yes, it regulates the output of the alternator. It can make the Aux Battery look bad, or make the Alternator look like it is defective. Mine crapped out, and was replaced, a year or so, into buying the jeep. All signs pointed towards the.Aux Batt then.

The IBS does not monitor the aux battery, just the main battery. It has no idea what the status of the aux battery is. And the only affect it has on the alternator is that if it reports that the main battery is not fully charged, the PCM will increase the alternator output to facilitate charging the main battery.

 

[DaltonGang]

@AlphaWrangler , what was the final outcome of your issue??

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[AlphaWrangler]

@AlphaWrangler , what was the final outcome of your issue??

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Well no issues now. Battery is charging fine just in time for my differential to lose a tooth

 

[DaltonGang]

Well, 2 months after bypassing the Aux Battery, and adding a larger main battery. The ESS isnt working. Probably because of the type of driving. I tend to push the button every time I get in anyway. Almost all quick trips, under 2 miles. It still starts up, nice and strong. Maybe I will put a trickle charger on it, overnight, and see if that does the trick for a while.

 

[Htfan]

... Almost all quick trips, under 2 miles. It still starts up, nice and strong. Maybe I will put a trickle charger on it, overnight...

With your short/quick trips, it's not enough to keep your battery fully charged. It seems using your trickle charger on a more regular basis would be the way to go.

 

[blnewt]

Well, 2 months after bypassing the Aux Battery, and adding a larger main battery. The ESS isnt working. Probably because of the type of driving. I tend to push the button every time I get in anyway. Almost all quick trips, under 2 miles. It still starts up, nice and strong. Maybe I will put a trickle charger on it, overnight, and see if that does the trick for a while.

ESS not working is a bad thing???

 

[DaltonGang]

ESS not working is a bad thing???

It's just an indication the main battery isn't fully charged. I despise the ESS on this Jeep. The Wife has a Toyota Highlander, and that thing works flawlessly. But, I push the disable button on that too.

 

[DaltonGang]

Well, I drove about 5 miles, and that fully charged the system. No need for the trickle charger.

 

[Htfan]

Well, I drove about 5 miles, and that fully charged the system. No need for the trickle charger.

Good to hear. How did you verify the battery was fully charged so quickly?

 

[DaltonGang]

Good to hear. How did you verify the battery was fully charged so quickly?

None of the dummy warnings came on, saying ESS isn't working because of battery charging. And, the silly ESS started shutting the engine off at stop lights. oh, I forgot to mention, my daughter drove it about 15 miles, the night before. So, those two drives had everything working as it should. I don't like the ESS system, at all, but its one purpose for me, is an indication of the battery and alternator health. That's just me.

 

[Htfan]

... oh, I forgot to mention, my daughter drove it about 15 miles, the night before. So, those two drives had everything working as it should....

Makes sense. Those two drives must have been enough charging time.

You can also monitor the JL's dash voltage while at cruising speed (not while braking/coasting). If it sticks at 14.4v-14.5v without lowering this can indicate there is a charging/battery issue brewing.

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