Battery Charging

[rr11]

Over the last several months my stop/start has be unavailable battery charging. I placed a battery maintainer over night. Next morning I do my usual drive of around a hour. System is ready 30 miles in I hit my first stop light and when the engine stops the voltage drops from 14.1 to 12.2 is this normal. Or this a indication of a week battery. I know the voltage with the motor running is alternator out put.

Sponsored

 

[obrianmcc]

your AUX is probably dying ... replace it or delete it. A bad AUX will also put a strain on the main. After I replaced the AUX my main died, so I chose to delete the AUX and upgraded the main to an Odyssey. No issues since.

 

[Andy29847]

The voltage shown during a stop/start event is the voltage of the aux battery. Your number, 12.2, is not unusual given that the volt reading is affected by whatever is turned on in the cab. The batteries have to be separated to determine which one is bad. My 2020 JT was doing the same thing, and it was the main battery that was bad. It was confusing to me at first because the main battery would test at 12.4. However, the design of the stop/start system seems to go offline at the 12.4 threshold. Your batteries are part of your new truck warranty. The dealer will test and replace them up to 3 years and 36,000 miles.

More info here: Start stop not ready / battery charging message after aux battery change - What next? | Page 3 | Jeep Gladiator Forum - JeepGladiatorForum.com

 

[Mr._Bill]

Over the last several months my stop/start has be unavailable battery charging. I placed a battery maintainer over night. Next morning I do my usual drive of around a hour. System is ready 30 miles in I hit my first stop light and when the engine stops the voltage drops from 14.1 to 12.2 is this normal. Or this a indication of a week battery. I know the voltage with the motor running is alternator out put.

The message is an indication of an electrical issue that needs checked. If you are driving over an hour each day, then the first step would be to have both batteries tested, as that should be enough to keep them charged. If the batteries are near three years old, they will likely need to be replaced.

 

[rr11]

The start/stop issue did not show up until I had 60,000 on the JT so it's on me. I appreciate the info at this time I'm trying to decide main, aux, both or bite the bullet and buy a dual system.

 

[Mr._Bill]

The start/stop issue did not show up until I had 60,000 on the JT so it's on me. I appreciate the info at this time I'm trying to decide main, aux, both or bite the bullet and buy a dual system.

The failure rates are mixed, so a proper load test is the best way to determine their condition. From your description, I would say you are at a point where both should be replaced.

 

[Lunentucker]

Yeah, those batteries are old enough and used enough to be near end of life.
You can pull fuse F42 and disconnect the AUX battery ground at the main ground group (tape it up to prevent incidental contact). That will take the AUX out of the game until you can decide what you want to do.
One common fix is the leave it that way and upgrade the main battery to a larger and higher capacity AGM battery.

 

[Andy29847]

The start/stop issue did not show up until I had 60,000 on the JT so it's on me. I appreciate the info at this time I'm trying to decide main, aux, both or bite the bullet and buy a dual system.

I would recommend a really good battery for the main. I'm thinking a group94/H7 battery with 900 Cold Cranking Amp. I would not replace the aux battery, I would isolate it by removing the aux negative form the main battery terminal. Insulate the removed end and tie it down somewhere. Then remove fuse F42 in you fuse box. Your truck will operate just like it always has only it will do this with one battery.

 

[rr11]

Thanks for the info, electrical on the newer computer & relay vehicles is not my strong suit. Worried about causing my self more problems. Servicing dealer is 75 miles away.

 

[rr11]

On a 2020 which of the neg wires on the main battery terminal is the aux neg?

 

[Lost1wing]

What I would do in your situation of being 75 miles out from your dealer, after disconnecting the negative at the fender. Charge both batteries independently by separating at the negative post of the main. The positive of the main battery is also the positive of the Aux if left connected. Just the two cables on the main need to be isolated to charge independently. While it is charging disconnect the ibs (sensor at the main negative post). When finished charging both batteries, reinstall the 2 negatives on the bracket, reinstall the bracket on the negative post, plug in the ibs and install the ground at the fender. If you have trouble getting one of you batteries to charge, it may be that battery is bad. You can measure voltage with a cheap VOM. Use an AGM battery charger.

 

[Andy29847]

Here is some info:

 

[Andy29847]

This is the big Jeep battery thread:

3.6L ESS Dual Battery Consolidated Information | Jeep Wrangler Forums (JL / JLU) - Rubicon, Sahara, Sport, 4xe, 392 - JLwranglerforums.com

 

[rr11]

I removed the crank battery and had NAPA test it and they said it was good. This leads me to believe the aux battery is bad. I guess my next move is to pull the fuse and the aux negative.

 

[Lost1wing]

Disconnect the ground at the fender. Remove and Isolate the 2 cables from the main negative bracket. Put your meter + on the main positive and then your - meter lead on either of the removed cables from the main negative post. The one that read 12v is you aux negative. The one that doesn't show any voltage is your main negative. It goes to the fender ground that you should have disconnect. Charge those batteries!

Sponsored