Aux and Main Batteries Dead

JeepEagle1

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Found no power in my 2018 JLRU Monday morning. Great.

Tried to jump start it to no avail so I had to have it towed to the dealer. The dealer found the main battery had less than 3V but the alternator was charging okay at 14.2V. Tested the main battery which failed and the auxiliary battery failed for a bad cell. Both batteries were replaced and the vehicle is running fine. Dealer said he had never seen this happen in a Jeep Wrangler before.
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theplankeye

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Now time to find the parasite that did it.
 

Rhinebeck01

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@JeepEagle1

If you could, tell us how you tried to jump start it.

  • Were you trying with a battery pack to your JL ?
  • Were you using battery cables between a donor vehicle and your JL?

I had a similar issue..... but was able to jump start the plain old fashion way 8-) , using another vehicle. I had tried with a battery pack, minutes before the successful jump start and the battery pack could not get the job done.
 

nanodaddy

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New Jeeper here with bad experience with my new 2018JL Sport S with 375 miles and 10 days on it. Broke down on the road with multiple error messages on the dash. Error messages - Electronic stability control/system failed, take to service. ESS not working, check engine light ON etc... Towed to the dealer. Dealer still unable to identify the root cause in addition to the bad battery. Even after battery replacement issues with PCM connectivity etc.

This issue is on top of the death wobble I am experiencing at 45 mph or higher speed. Dealer is working on mine for the last 7 days!!!

Did anyone of you experienced similar issues? Should I file for lemon vehicle?
 

Jebiruph

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Found no power in my 2018 JLRU Monday morning. Great.

Tried to jump start it to no avail so I had to have it towed to the dealer. The dealer found the main battery had less than 3V but the alternator was charging okay at 14.2V. Tested the main battery which failed and the auxiliary battery failed for a bad cell. Both batteries were replaced and the vehicle is running fine. Dealer said he had never seen this happen in a Jeep Wrangler before.
This may have helped get it started - https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/. In your case, had you known the Aux battery was bad, the bypass plus disconnecting the Aux battery ground cable from the Main battery terminal should remove the Aux battery from the jump start process. As to what drained the batteries, low voltage from a bad Aux battery would be a constant draw on the Main battery.
 

theplankeye

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Not sure I buy that these batteries just go bad, especially simultaneously (extremely improbable). I think there must be something else in the system causing the problem.
 

Jebiruph

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Not sure I buy that these batteries just go bad, especially simultaneously (extremely improbable). I think there must be something else in the system causing the problem.
If I connect two batteries in parallel that have different voltages, the higher voltage battery will charge the lower voltage battery until the voltages are equal. If one of the batteries is defective and can't hold a charge, what will that do to the good battery. After market dual battery systems usual have a battery isolator to prevent the batteries from discharging each other.
 
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JeepEagle1

JeepEagle1

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@JeepEagle1

If you could, tell us how you tried to jump start it.

  • Were you trying with a battery pack to your JL ?
  • Were you using battery cables between a donor vehicle and your JL?

I had a similar issue..... but was able to jump start the plain old fashion way 8-) , using another vehicle. I had tried with a battery pack, minutes before the successful jump start and the battery pack could not get the job done.
I tried two separate battery packs (1 small and 1 large one) and neither one worked. The battery packs would turn on the lights, radio, wipes, windows, etc., but the engine would not start. The dealer thought that the defective auxiliary battery had impacted the main battery. The vehicle seems to be running fine now with the new batteries with the alternator running in the normal range (12.6-14.2).
 
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JeepEagle1

JeepEagle1

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This may have helped get it started - https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/. In your case, had you known the Aux battery was bad, the bypass plus disconnecting the Aux battery ground cable from the Main battery terminal should remove the Aux battery from the jump start process. As to what drained the batteries, low voltage from a bad Aux battery would be a constant draw on the Main battery.
Yes. This seems to be the case.
 

Rhinebeck01

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I tried two separate battery packs (1 small and 1 large one) and neither one worked. The battery packs would turn on the lights, radio, wipes, windows, etc., but the engine would not start. The dealer thought that the defective auxiliary battery had impacted the main battery. The vehicle seems to be running fine now with the new batteries with the alternator running in the normal range (12.6-14.2).
@JeepEagle1

IF you are ever are in a similar situation where you need to jump start your JL, forget the battery packs and just jump using battery cables to a 12v donor vehicle that has a decent 12v battery(s) .

With the donor vehicle running, attach your battery cables and let things be for say a couple of minutes, then try to start the JL..

As I mentioned in my earlier post, I tried battery pack as the 12v donor and all I could get was dash lights on and little more. As soon as I did the cables with donor as I mentioned, the JL started right up. My JL had depleted batteries, so once batteries were charged I was good to go...

.
 

Rhinebeck01

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This may have helped get it started - https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/. In your case, had you known the Aux battery was bad, the bypass plus disconnecting the Aux battery ground cable from the Main battery terminal should remove the Aux battery from the jump start process. As to what drained the batteries, low voltage from a bad Aux battery would be a constant draw on the Main battery.
@Jebiruph
@JeepEagle1

I will remember this.. IF I had done this, the battery pack I used for donor 12v would probably been able to start my JL. The battery pack probably would have done the deed if I had done this.
 

JeepCares

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New Jeeper here with bad experience with my new 2018JL Sport S with 375 miles and 10 days on it. Broke down on the road with multiple error messages on the dash. Error messages - Electronic stability control/system failed, take to service. ESS not working, check engine light ON etc... Towed to the dealer. Dealer still unable to identify the root cause in addition to the bad battery. Even after battery replacement issues with PCM connectivity etc.

This issue is on top of the death wobble I am experiencing at 45 mph or higher speed. Dealer is working on mine for the last 7 days!!!

Did anyone of you experienced similar issues? Should I file for lemon vehicle?
Hi nanodaddy,

We are sorry to hear that you have this concern with your new Jeep Wrangler. If you are in need of additional assistance while your Jeep is in service, please send us a private message.

Darlene
Jeep Social Care Specialist
 
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JeepEagle1

JeepEagle1

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@Jebiruph
@JeepEagle1

I will remember this.. IF I had done this, the battery pack I used for donor 12v would probably been able to start my JL. The battery pack probably would have done the deed if I had done this.
I agree. I hope that I won't have this problem again, but if I do, I'll definitely use the workaround for bypassing the aux battery.
 

subiescott77

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I had the same issue after coming back from vacation but was told my alternator was bad and not maintaining proper voltage. I thought it read 14 or so while idling in my driveway after having it on a charger all night. I was additionally told my batteries were both normal after being tested. Ideas???
 

Lar

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Posted on another blog but just went through the twin dead battery issue with my 2 year old JLU. Car sat for about 6 days leading up to the failure but that should not be enough to kill both batteries. Took quite a bit of power to get it started but tow truck was able to finally get it to turn over. Towed to dealer . No issues with alternator , no drain. Dealer said perhaps the proximity feature (makes no sense to me as i believe it doesn't do anything until it receives a signal that the key fob is close in proximity. There thought it is "working" all the time and draining the battery.
Also said that when one battery goes the other will drain out as well. Both batteries replaced under warranty this time but I'm guessing next time will be on me ( about $ 300. plus for both batteries) assuming i am going to be replacing them every two years. between the cracked windshields and the dead batteries the yearly costs to run this vehicle are climbing. Not to mention the plain pain in the a-- to have to be towing it back to the dealer every few months. And like all the newer computer driven vehicles when the power ie battery goes you will get all kinds of electronic glitches . Have had that on other vehicles as well. And that includes the key fob battery for some reason. Seems that the computer doesn't like it when it doesn't get it's allotted power. Weird codes thrown, wipers start slowly and stop on their own , lights flash quickly in the vehicle. Crazy stuff but all goes away when it gets it's fresh power source..
Although I know this is not new technology but my money is on the auto start function being part of the problem. I may have to get used to disabling it every time i start the car as well as placing it on a smart charger every time it's not driven for more than a day or so.
In my humble opinion should n't be happening on a $56K vehicle, or any vehicle for that matter..
 
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