Battery Issues Aux battery not charging

[CSYeep]

I have a 2020 Gladiator Sport, I got stuck on the side of the road when the ESS failed to restart and it gave me a light show on the dash with all the gages flashing and the windshield wipers randomly going off. tried to jump start it with no luck and had to get it towed. once i got it home had to disconnect both batteries to get the lights to stop. the Aux battery was dead and the main was about 1/3 charged. I replaced the Aux battery with a new one and made sure it was fully charged before installing it and charged the main. the jeep ran good for the first day with no problems, on the 2nd day it wouldn't start pulled both batteries and again the aux was dead and the main was about 1/3 charged. i recharged both batteries and started to check the fuses and found the N3 blown. I changed that out and reinstalled both batteries when driving around i get the ESS error low voltage warning and things like the AC, AUX phone charger, my pod lights and power step will not work. when watching the voltage it started out at 13.9 while driving and then dropped down to 12.6 at the lowest and is now back to 13.9 this was over 5 days. I don't want to do any kind of aux battery delete as i have some kind gremlin that is drawing power off the aux battery killing it. i keep reading it could be the PCR relay/fuse that bad but i can't find where that stupid thing is located on a gladiator (i just keep getting pic for a wrangler or cherokee). am i on the right track or should i look at something else????

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[Mr._Bill]

Replace the Main Battery. You should have replaced it with the Aux Battery. They are paralleled together all the time, except during the startup test and during ESS events. The failing Main Battery is draining the new Aux Battery.

 

[CSYeep]

thats on the todo list, the only thing that keeps it off the top of the list is with the main battery disconnected once i connect the aux it starts to drain with nothing turned on, something is stuck pulling power off the aux and is doing it faster then it can recharge while driving or just keeping it from recharging all together

 

[Mr._Bill]

thats on the todo list, the only thing that keeps it off the top of the list is with the main battery disconnected once i connect the aux it starts to drain with nothing turned on, something is stuck pulling power off the aux and is doing it faster then it can recharge while driving or just keeping it from recharging all together

The Aux Battery will drain faster due to its lower capacity. The computers and head unit are on all the time, they never shut off. You need to get the electrical system in proper working order, and then chase down any issues. Letting the failing Main Battery drain the Aux Battery every day is going to kill it soon.

 

[Pakdoc]

Yes, and unless under warranty, DO NOT replace with a MOPAR battery as they (I've had 4) all seem to fail before 3 year warranty...and they will not replace IF you received a new one under the Jeep Warranty...on;y if you buy the battery separately......which I feel they replaced my batteries with defective batteries that do not last 3 years but refuse the 3 yr warranty...... i'm out of breathe now.

 

[Shibbyjeep]

Just bypass/get rid of the AUX and replace the main battery.

 

[CSYeep]

**UPDATE**
replaced the main battery and was still getting low voltage to the point when the test drive was done the jeep shut down. the new aux battery was dead when i got the jeep back to the house. replaced the alternator, and am still having issues with low voltage and the aux battery not charging. I'm going to swap the aux battery tomorrow is there anything that i'm over looking that could be causing issues, its getting old chasing this gremlin

 

[RJ McAuliffe]

**UPDATE**
replaced the main battery and was still getting low voltage to the point when the test drive was done the jeep shut down. the new aux battery was dead when i got the jeep back to the house. replaced the alternator, and am still having issues with low voltage and the aux battery not charging. I'm going to swap the aux battery tomorrow is there anything that i'm over looking that could be causing issues, its getting old chasing this gremlin

I had similar issues and caught it before the warranty was up - had the dealership change the Intelligent battery system sensor - Charging immediately went to 14.6v. I only see 12.4 with the engine off and several accessories. I suggest you get the IBS sensor changed out and the IBS program reset.

 

[CSYeep]

I had similar issues and caught it before the warranty was up - had the dealership change the Intelligent battery system sensor - Charging immediately went to 14.6v. I only see 12.4 with the engine off and several accessories. I suggest you get the IBS sensor changed out and the IBS program reset.

no warranty.... =( but will look into that thanks

 

[sharpsicle]

I had similar issues and caught it before the warranty was up - had the dealership change the Intelligent battery system sensor - Charging immediately went to 14.6v. I only see 12.4 with the engine off and several accessories. I suggest you get the IBS sensor changed out and the IBS program reset.

If it's always at 14v, that means your battery/batteries are never getting to full charge. Smart alternators should switch to float voltage on a healthy and charged battery system.

 

[Andy29847]

I have a 2020 Gladiator Sport, I got stuck on the side of the road when the ESS failed to restart and it gave me a light show on the dash with all the gages flashing and the windshield wipers randomly going off. tried to jump start it with no luck and had to get it towed. once i got it home had to disconnect both batteries to get the lights to stop. the Aux battery was dead and the main was about 1/3 charged. I replaced the Aux battery with a new one and made sure it was fully charged before installing it and charged the main. the jeep ran good for the first day with no problems, on the 2nd day it wouldn't start pulled both batteries and again the aux was dead and the main was about 1/3 charged. i recharged both batteries and started to check the fuses and found the N3 blown. I changed that out and reinstalled both batteries when driving around i get the ESS error low voltage warning and things like the AC, AUX phone charger, my pod lights and power step will not work. when watching the voltage it started out at 13.9 while driving and then dropped down to 12.6 at the lowest and is now back to 13.9 this was over 5 days. I don't want to do any kind of aux battery delete as i have some kind gremlin that is drawing power off the aux battery killing it. i keep reading it could be the PCR relay/fuse that bad but i can't find where that stupid thing is located on a gladiator (i just keep getting pic for a wrangler or cherokee). am i on the right track or should i look at something else????

Problems like yours is a big part of what drove me to using a single battery.

Peace of mind at last! Replaced main battery with a premium H7/Group 94 battery | Jeep Gladiator (JT) News, Forum, Community - JeepGladiatorForum.com

 

[RJ McAuliffe]

If it's always at 14v, that means your battery/batteries are never getting to full charge. Smart alternators should switch to float voltage on a healthy and charged battery system.

Agreed. It's not always > 14v, but it is capable of it. OP said: "...watching the voltage it started out at 13.9 while driving and then dropped down to 12.6 at the lowest and is now back to 13.9 ..."
System should be topping out at "need" around 14.7 and then floating.

 

[sharpsicle]

Agreed. It's not always > 14v, but it is capable of it. OP said: "...watching the voltage it started out at 13.9 while driving and then dropped down to 12.6 at the lowest and is now back to 13.9 ..."
System should be topping out at "need" around 14.7 and then floating.

Right. What OP is seeing for voltage is completely normal for a smart alternator.

 

[Andy29847]

Right. What OP is seeing for voltage is completely normal for a smart alternator.

I wrote this in 2023:
The Intelligent Battery Sensor (IBS) is not smart. It is just a sensor.

The Smart Alternator is dumb. When it is winter (cold), it just charges along at 14.5-14.7, regardless of the state of charge of the battery.

The Jeep 2 battery system is effectively just one battery. Except for a start/stop event, the 2 batteries are connected together, which geometrically increases a Jeep owner's chance for battery trouble. Very little is gained by allowing some of the cab loads to be handled by the aux battery during a stop/start event. Much is lost when the batteries get near their end-of-life. Jeep could have installed a bigger better main battery, eliminated the aux battery, and saved money.

The design of the Jeep battery and charging system make it very hard to deduce useful information from the Jeep's voltmeter. For example, if your voltmeter is reading in the 12's, you may have 2 fully charged batteries or your alternator may have taken a dump. Drive a while and find out. If the Smart alternator and IBS were really smart, we could get a dash readout on the state of our batteries both together and individually.

If Santa is keeping tabs on the engineers and bean counters that conspired to give us the battery/charging system in our new Jeeps, those guys are not going to get presents.

Merry Christmas to all, and to all a good night.

 

[Minty JL]

You have a '20, its time for new batteries. I got 4 years out of mine in the JLUR and had to replace. The first indicator was the remote start would not work. SO I load tested them and it was clear they were toast.

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