Drained Battery, Any jumpstart tips??

[WranglerMan]

My wish is I wish FCA had never done the whole duel battery system, if if had be engineered correctly by just putting the aux battery in a more user friendly location that would have be ok but they buried the dam thing so my only hope when the aux battery craps out is to use my jumper on N1 to N2 and remove the ESS negative which takes it out of the picture then jump start the Jeep and either replace both batteries ( Unlikely ) or run with the jumper as a permanent install with the ESS negative removed ( Highly Likely )

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[Leisure Freak]

My wish is I wish FCA had never done the whole duel battery system, if if had be engineered correctly by just putting the aux battery in a more user friendly location that would have be ok but they buried the dam thing so my only hope when the aux battery craps out is to use my jumper on N1 to N2 and remove the ESS negative which takes it out of the picture then jump start the Jeep and either replace both batteries ( Unlikely ) or run with the jumper as a permanent install with the ESS negative removed ( Highly Likely )

I'm with you WranglerMan. I carry a 30 amp fused jumper with wingnuts in a sandwich zip lock bag in my glove box just for that inevitable special day. I had 3 premature battery deaths last summer with other cars so I figure the Jeep's buried aux battery will wait for the most inopportune time to take a crap.

 

[JeepCares]

Sunday my battery died after leaving in ACC overnight. Long story short, much like others here, charger did nothing, quick jump got a turnover and then nothing, prolonged charging via the jump start brought her around to start. YAY! Bad news.. and I need to ask the dealer more about this issue, once started and run for an hour, the ESS WARNING light came on and said take to dealer. My infotainment system never came back on. No radio, backup camera (although the sensors still worked on the display cluster), no display of heat controls, no USB port connections etc. Took it to the dealer and they said “an underlying problem with the system caused the aux battery to go bad and that somehow shorted the head unit and a hood pin switxh”. They are replacing the battery, hood pin, and ordering a new head unit which I was told by them would take 1-2 months to get in. Guess I will be practicing my whistling skills for a few months.

We're happy to hear you made it to the dealer for this concern, 2Wander. Please let us know how repairs go.

Kate
JeepCares

 

[jeepdabest]

So, with all the drama regarding small jump boxes would it be best to carry the old school 90lb jump box?

You can get a JNC 660 or 770 that weigh about 20 lbs each.

 

[Gee-pah]

Since this thread was created, and as discussed on some other threads, in seems that FCA has changed the cold crank procedure on 2019 and beyond 3.6L JLs.

When the 3.6L JL was released in 2018, the rig's cold start procedure, upon user initiated and authenticated (your fob passed as valid by battery or touch to the start button) request to start the vehicle, tested the ESS/Aux battery in isolation for adequate power first, prior to attempting a crank.

If that threshold wasn't cleared, which seems to be a power level that's lower than that required for ESS to kick in at red traffic lights, the rig wouldn't even attempt a crank. Your main battery's power level didn't matter at this point in the crank procedure. If this test passed, both batteries were rejoined in parallel to each contribute to the cranking process.

This was substantiated in part by tests early in the JL's model life where the rig would crank with no problem when connected only to a adequately powered ESS/Aux battery alone, but not the main battery alone.

Now, reports are coming in that the 2019 3.6L JLs and beyond will cold crank if either battery has adequate power: the way IMHO it always should have been...my theories on why it was originally designed this way the subject of other posts.

None of this changes the need for the occasional jump start, but perhaps how a power source is optimally connected to the rig--especially one whose power levels may barely be enough to get the rig going. Originally I suggested hooking such a pack up to the ESS battery and separating it from the main battery so precious power pack juice wasn't wasted on first charging both batteries, especially the main battery. (At rest both batteries are connected in parallel so putting jumper cables on either battery is to put them on both batteries.)

Now..I think that may be unnecessary, I just don't know.

And I simply don't know if the change in start logic was downloaded to 2018 JLs as well.

 

[TimmH]

Since this thread was created, and as discussed on some other threads, in seems that FCA has changed the cold crank procedure on 2019 and beyond 3.6L JLs.

When the 3.6L JL was released in 2018, the rig's cold start procedure, upon user initiated and authenticated (your fob passed as valid by battery or touch to the start button) request to start the vehicle, tested the ESS/Aux battery in isolation for adequate power first, prior to attempting a crank.

If that threshold wasn't cleared, which seems to be a power level that's lower than that required for ESS to kick in at red traffic lights, the rig wouldn't even attempt a crank. Your main battery's power level didn't matter at this point in the crank procedure. If this test passed, both batteries were rejoined in parallel to each contribute to the cranking process.

This was substantiated in part by tests early in the JL's model life where the rig would crank with no problem when connected only to a adequately powered ESS/Aux battery alone, but not the main battery alone.

Now, reports are coming in that the 2019 3.6L JLs and beyond will cold crank if either battery has adequate power: the way IMHO it always should have been...my theories on why it was originally designed this way the subject of other posts.

None of this changes the need for the occasional jump start, but perhaps how a power source is optimally connected to the rig--especially one whose power levels may barely be enough to get the rig going. Originally I suggested hooking such a pack up to the ESS battery and separating it from the main battery so precious power pack juice wasn't wasted on first charging both batteries, especially the main battery. (At rest both batteries are connected in parallel so putting jumper cables on either battery is to put them on both batteries.)

Now..I think that may be unnecessary, I just don't know.

And I simply don't know if the change in start logic was downloaded to 2018 JLs as well.

Would be nice to get an answer from Jeep on this, and if it's possible to reprogram 2018's to operate this way.

 

[jeepdabest]

I would disconnect the aux negative cable and jump the main battery on 2019 and above.

 

[Gee-pah]

I would disconnect the aux negative cable and jump the main battery on 2019 and above.

The would seem to make sense Bobby. Why waste one drop of power on a battery (ESS/Aux) that 2019 3.6L's don't need to crank. Once cranked, the alternator can charge both batteries, presuming your disconnect aux battery negative cable is reconnected to the main battery after successfully cranking.

 

[2Wander]

We're happy to hear you made it to the dealer for this concern, 2Wander. Please let us know how repairs go.

Kate
JeepCares

They had the Jeep for about a week. Most of that was in us for not being able to pick it up. Randomly, the day we were coming to pick it up the dealership called and said they suddenly had a new head unit. YAY! They put it in and we have the Jeep backjust in time for warm weather!

On a less happy note, the ESS and all my media ports are not working. Back to the dealership. Oh and they managed to drop oil all over the engine bay doing my Jeep wave oil change.. oh well, it’s a Jeep gotta love the smell of burning oil!

 

[jeepdabest]

They had the Jeep for about a week. Most of that was in us for not being able to pick it up. Randomly, the day we were coming to pick it up the dealership called and said they suddenly had a new head unit. YAY! They put it in and we have the Jeep backjust in time for warm weather!

On a less happy note, the ESS and all my media ports are not working. Back to the dealership. Oh and they managed to drop oil all over the engine bay doing my Jeep wave oil change.. oh well, it’s a Jeep gotta love the smell of burning oil!

It ju

They had the Jeep for about a week. Most of that was in us for not being able to pick it up. Randomly, the day we were coming to pick it up the dealership called and said they suddenly had a new head unit. YAY! They put it in and we have the Jeep backjust in time for warm weather!

On a less happy note, the ESS and all my media ports are not working. Back to the dealership. Oh and they managed to drop oil all over the engine bay doing my Jeep wave oil change.. oh well, it’s a Jeep gotta love the smell of burning oil!

The dealer will always put their best mechanics in the quick lube.

 

[JeepCares]

They had the Jeep for about a week. Most of that was in us for not being able to pick it up. Randomly, the day we were coming to pick it up the dealership called and said they suddenly had a new head unit. YAY! They put it in and we have the Jeep backjust in time for warm weather!

On a less happy note, the ESS and all my media ports are not working. Back to the dealership. Oh and they managed to drop oil all over the engine bay doing my Jeep wave oil change.. oh well, it’s a Jeep gotta love the smell of burning oil!

Glad to hear your initial concerns were resolved, 2Wander. If you need assistance with the other ones, please let me know.

Kate
JeepCares

 

[Kripas]

I have 2018 2.0 Turbo. My 12V Battery totally died on me , 0% juice, no light no acc no radio. I have a 900 amp jump battery and tried using it and it just sucked up on it and could not start. Called a Service road to jump using his jump start battery a bigger one but still no go. Then we tried the old fashion way, using a jumper cable - A car donor battery ( his car while it's running from his battery to my Jeep 12V battery using jumper cable and viola!!! The Jeep started.

 

[Yann]

When you are trying to jump start your jeep, the critical hurdle is getting enough power to the starter to crank the engine. Connecting the jump starter as close to the starter as possible reduces power loss caused by the accumulated wire and connection resistance. @Gee-pah, as you can see in this diagram, your method goes B (N1) - aux - PCR - N3 - PCR fuse - N2 - main - starter. This puts you as electrically far away from the starter as possible, putting the maximum amount of power robbing resistance in the path of the jump start. You also risk blowing the 150A PCR fuse. It is better to jump start using the main battery positive terminal (A) and manage the batteries with the negative cables, N1 to N2 jumper or unplugging the PCR as necessary.

As your described why not derict hook jump pack on N1 & main negative post? it will help pass the pre-crank check and boost crank...

 

[Jebiruph]

As your described why not derict hook jump pack on N1 & main negative post? it will help pass the pre-crank check and boost crank...

Some have had success doing this to circumvent aux battery problems, but then it's possible for some or all of the starting current to transverse all the ESS circuitry and the owners manual was updated to warn against doing this.

 

[Yann]

Some have had success doing this to circumvent aux battery problems, but then it's possible for some or all of the starting current to transverse all the ESS circuitry and the owners manual was updated to warn against doing this.

Thx. sounds reasonable.

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