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Jumping your Jeep..... who has done it with a battery pack?

Gee-pah

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Except, what I learned from another thread is that the Jeep JL (at least 2019s and 2020s, it appears) WILL start from the main battery if you disconnect the aux battery. So, in the case of a bad aux battery, disconnect the negative aux battery lead and jump the main battery as normal with a jumper pack.

https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/page-20
Thank you Bobby. I did not know that FCA changed the logic for start of the 2019's and beyond. I'd like to think the letter I sent to the President of FCA on why the 2018 design was stupid, and how to so easily correct it with a simple start up logic change had an effect but I doubt it.

I think that logic change should also happen in the 2018!
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Uh, I can start my Jeep without the aux connected and jump it without the aux connected.
As I indicated somewhere else on the forum Bobby, I stand corrected on the cold startup logic for the 2019 JL's and beyond thanks to your informing me as such.

Thanks.

(I wonder if my 2018 will get a download to act this way too.)
 

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A few questions:
When the JL starter is engaged, does the system use the main battery only, ESS only, or join the main battery and ESS together?
When accessories run on the system (radio, fridge, etc.) does the power come from the main, ESS, or both?
It appears that I have been corrected. Here's what I understand that's changed in my comprehension on this matter since earlier today:

The 2018 3.6L JL, at least back in 2018, tested the ESS/Aux battery for power in isolation just prior to crank, and if this power was adequate, connected both batteries in parallel to supply power to the crank.

This meant that with no ESS/Aux battery, or a dead one, you weren't going anywhere even if your main battery was fully charged. OIf course, since both batteries are connected in parallel when the rig is at rest--or at least they were in 2018, such a situation might have caused a drained ESS/Aux battery to drain the main one charging.

Enter 2019--and I just found this out minutes ago. It seems 2019 3.6L owners are reporting (as I screamed at FCA's President in writing 2 years ago that the 2018 logic here was stuipid and how to change it) that if either battery has power the cold crank should occur.

Now--does this mean that the logic change was or will also be downloaded to the 2018 3.6L, I simply don't know.:)

As far as accessories go, when the rig is in an ESS event, it was my understanding (at least on the 2018) that power for things was acquired from the ESS battery. Jerry @Jebiruph then informed me that power steering still got its power from the main battery.

When the 3..6JL is at rest, at least in 2018, both batteries were connecting in parallel and as a result, connecting to either was the equivalent of connecting to both.

Now--who knows. My guess would be that the only thing that's changed is that either battery in the 3.6L from 2019 and on can cold crank the rig.
 

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Question, does the 2019 Owner's Manual still say to wait a while after connecting the jumper cables before attempting a crank?

I ask, because much of this had to do with the 2018 3.6L getting from the jumper cables some charge the ESS/Aux battery, which seemed to have to have some basic voltage when testing by the rig in isolation for the 2018 3.6L to even attempt the cold crank.

If either battery will now cold crank, and one hooks their jumps up (in parallel) to the main battery, you'd think such wait times would not be as necessary.

Thanks.
 
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roaniecowpony

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Question, does the 2019 Owner's Manual still say to wait a while after connecting the jumper cables before attempting a crank?

I ask, because much of this had to do with the 2018 3.6L getting from the jumper cables some charge the ESS/Aux battery, which seemed to have to have some basic voltage when testing by the rig in isolation for the 2018 3.6L to even attempt the cold crank.

If either battery will now cold crank, and one hooks their jumps up (in parallel) to the main battery, you'd think such wait times would not be as necessary.

Thanks.
I'm not following you. All the JL owner manuals from 2018 to 2020 have the same procedure.
"Start the engine in the vehicle that has the
booster battery, let the engine idle a few
minutes, and then start the engine in the
vehicle with the discharged battery."

I think you'll find that same procedure in every FCA owners manual. I looked at a Ram 2500, which has no ESS, and it had the same words.

This is from a 2019 Chevy Silverado manual:
" Start the vehicle with the good
battery and run the engine for a
while."

I'm in my 60s. My dad taught me, before I was old enough to drive, to let the jumper vehicle charge the dead vehicle for a while if it didn't start on the first try or if you know it's really drained. Virtually anyone that has been around jump starting knows to let the boosting battery charge the dead battery for a while. It's because the total resistance between the charged battery and the dead battery, in the cables, connections, and internal battery resistance limits the rate at which current can flow between the two batteries (or three, or four, or twenty, whichever is the case). Whiskey-Tango-Foxtrot, over :whatsgoingon:
 
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Is there a way to determine if the 2018 units can be updated? Is there a way to view firmware version on the screen?
 

roaniecowpony

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Is there a way to determine if the 2018 units can be updated? Is there a way to view firmware version on the screen?
Back to the topic of this thread, the procedure for jump starting the JL has remained the same for 2018, 2019, and 2020. Connect the jump pack or jump vehicle, to the JL in the same manner as any other vehicle.
 
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Back to the topic of this thread, the procedure for jump starting the JL has remained the same for 2018, 2019, and 2020. Connect the jump pack or jump vehicle, to the JL in the same manner as any other vehicle.
Actually, the topic of the thread is JUMP PACKS that will actually work to Jump a JL. So far, there are 3 or 4 listed above that have proven to work. additional models will hopefully be added along with they engine type jumped 3.6L with ESS, 2.0T BSG, etc.
 

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Actually, the topic of the thread is JUMP PACKS that will actually work to Jump a JL. So far, there are 3 or 4 listed above that have proven to work. additional models will hopefully be added along with they engine type jumped 3.6L with ESS, 2.0T BSG, etc.
David..I take no issue with your above statement. Thank you for it. But I do wish to make a point, it may sound nick picking but it's I believe relevant.

Several portable jump starters have been proven to work, but what hasn't been held constant in such testing, at least I don't think it has, is the amount of current in the (3.6L) JL's batteries when this jump starting was done.

These vehicles, assuming they didn't have enough juice to crank themselves, may have had batteries just below the threshold of being able to crank the JL on their own, or been near dead, or at some level in between these two extremes.

I'd like to know which of these packs, if any, can turn over the JL's whose batteries are not defective, but near dead with respect to power, and as a result of not being defective, capable of taking a charge.:)

I fully get the desire to remain on topic. The issue is that with the 2018 3.6L JL at least, understanding how the cold crank works is an integral part of understanding not only what power packs are best, but how to hook them up--which may be (at least for the 3.6L 2018's) a direct connection to the ESS battery with a fused jumper between high amp fuses N1 and N2 in the Power Distribution Center.

I get that that's a mouthful. And if FCA is incorporating this logic change to the 2018 3.6JL's via some download--an unknown at this time--then power packs will no longer have to charge the ESS battery first, and then provide power for the cold crank.
 
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This is a little taxing, I am a Land Rover guy and love the hell out of them, yes they have issues but you can do basic thing like jumpstart them lol, I have used my basic jump pack on all three with ZERO problems. I bought a Jeep because I wanted simple, reliable and basic Kinda like old school but after reading all the posts on here I am starting to think I messed up buying a jeep and the funny thing is my title came in yesterday. Living in Vegas with the summer heat you are lucky to get two-three years out of a battery so I'm curious how long the little battery will last.
 

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I'm not following you. All the JL owner manuals from 2018 to 2020 have the same procedure.
"Start the engine in the vehicle that has the
booster battery, let the engine idle a few
minutes, and then start the engine in the
vehicle with the discharged battery."

I think you'll find that same procedure in every FCA owners manual. I looked at a Ram 2500, which has no ESS, and it had the same words.

This is from a 2019 Chevy Silverado manual:
" Start the vehicle with the good
battery and run the engine for a
while."

I'm in my 60s. My dad taught me, before I was old enough to drive, to let the jumper vehicle charge the dead vehicle for a while if it didn't start on the first try or if you know it's really drained. Virtually anyone that has been around jump starting knows to let the boosting battery charge the dead battery for a while. It's because the total resistance between the charged battery and the dead battery, in the cables, connections, and internal battery resistance limits the rate at which current can flow between the two batteries (or three, or four, or twenty, whichever is the case). Whiskey-Tango-Foxtrot, over :whatsgoingon:
Thanks for the info. Let me clarify.

Historically, the real purpose of letting a jump starting vehicle (i.e. the one supplying the power to the dead vehicle) sit for a while with its engine on was to allow this vehicle's alternator to top off the vehicle's battery for the impending large donation of power it was about to give the vehicle which could not cold crank.

Along these lines, no tow truck, with its heavy duty power sources and quick connect jumper cables ever waited much after connecting these cables to one on my dead vehicles before the crank was attempted. These trucks had batteries with more than ample capacity, and what little wait time was involved probably just gave my vehicle's dead battery "some" basic miniscule charge. With the starting vehicle's jumper cables remaining connected in parallel, (this is the important part), the cold crank of the dead vehicle was attempted and almost invariably successful.

The 2018 JL, at least with the 3.6L engine, presented a whole new reason for this waiting period apart from the above. In this JL, the two batteries are/were connected in parallel at all times but for ESS events and an instant at startup, where prior to the cold crank, a quick test of the ESS battery, in isolation, was effected, to make sure it had an essential threshold of power, before both batteries would be reconnected to supply power to the cold crank. In absence of some basic power in the ESS battery, the crank would not be attempted, even if the main battery had been substituted with "a nuclear power plant...."

...why it was designed this way---a topic for another thread.

For this 2018 3.6L JL the waiting period involved--in addition to your "father's reason" for waiting before the crank--the new reason of charging the ESS battery described above, in its parallel connection to the main battery that you hooked your jumper cables to (also charging the main battery in the process) was necessary.

Enter 2019. I'm now hearing, gladly I might add, that the cold crank logic allows either and both batteries, as long as they have power, to cold crank--not require the ESS battery to have a basic level of power all on its own.

And as a result I was wondering if this change in design reflected rewording in the owner's manual.
 

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This is a little taxing, I am a Land Rover guy and love the hell out of them, yes they have issues but you can do basic thing like jumpstart them lol, I have used my basic jump pack on all three with ZERO problems. I bought a Jeep because I wanted simple, reliable and basic Kinda like old school but after reading all the posts on here I am starting to think I messed up buying a jeep and the funny thing is my title came in yesterday. Living in Vegas with the summer heat you are lucky to get two-three years out of a battery so I'm curious how long the little battery will last.
Kevin...it sounds like your concerns may not be warranted from information I literally didn't know yesterday in this time.

Knowledgeable people on the board have reported that with the 2019 JL and beyond, at least those with the 3.6L engine, a cold crank will be attempted if either battery has ample power.

It was in the 2018 model, and this design may change even in the 2018 if FCA downloads logic changes, that prior to attemting a cold crank, an isolated test of the ESS battery was made, and that if it didn't hold a basic threshold of power, no crank would be attempted, even if your main battery was substituted for a "nuclear power plant."

There is a rub here. I am assuming that like in the 2018 3.6JL, the two batteries are connected in parallel at all times but during ESS events (if not also the instant at startup in the 2018). The implications of this design is that power will flow between the two batteries from the one with more power to the one with less while the vehicle's at rest. Hopefully this power difference is minimal when all works well, but in theory, if one battery is defective and a parasitic black hole of power that draws charge from the other, but is unable to process it into its battery's chemistry, both batteries could be effected.

I know of no stop gap measure from the factory--which is NOT to say one doesn't exist--that puts a limit on such drains.
 

roaniecowpony

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I'd like to know which of these packs, if any, can turn over the JL's whose batteries are not defective, but near dead with respect to power, and as a result of not being defective, capable of taking a charge.:)
That linked video to the "Project Farm" guy shows at least the batteries tested were all over the map on capability. But some of them did actually have enough energy crank that tractor pretty lively without any other battery. When you're dealing with products made overseas without any standards, you get wide variability. If I were to buy another jump pack today, I'd probably just buy the Audew tested in that video.https://www.audew.com/Audew-2000A-P...D-Power-Display-p-100058.html?rmmds=product_4
 

roaniecowpony

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Thanks for the info. Let me clarify.

Historically, the real purpose of letting a jump starting vehicle (i.e. the one supplying the power to the dead vehicle) sit for a while with its engine on was to allow this vehicle's alternator to top off the vehicle's battery for the impending large donation of power it was about to give the vehicle which could not cold crank. ...
I believe your conclusion in the above is incorrect.

If your statement were correct, all the instructions and historical procedures would just have the jump start vehicle start and run for a period of time, thereby topping the battery before hooking up the jump cables, and immediately start the dead vehicle. But that's not the case. All the procedures from FCA vehicles and the GM vehicles I provided quotes for and my own experience indicate connecting the jump vehicle to the dead vehicle for a period of time, charges the dead vehicle's battery (if the battery is not defective and will accept a charge) and assists in starting the dead vehicle. The reason this helps in most cases with consumer jumper cables and another vehicle is supported by your example of a heavy duty commercial jump start device with very large (low resistance) cables and large power source. Consumer jumper cables (and jump packs) are limited in their ability to provide a large surge (cranking) by the total resistance between the jump battery and the dead battery(s). Remember: the longer the cable, the higher the resistance. The smaller the gauge of the cable, the higher the resistance. Jumper cable clamps are not so great for resistance either. That's why a battery post has so much contact area.
 

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I believe your conclusion in the above is incorrect.

If your statement were correct, all the instructions and historical procedures would just have the jump start vehicle start and run for a period of time, thereby topping the battery before hooking up the jump cables, and immediately start the dead vehicle. But that's not the case. All the procedures from FCA vehicles and the GM vehicles I provided quotes for and my own experience indicate connecting the jump vehicle to the dead vehicle for a period of time, charges the dead vehicle's battery (if the battery is not defective and will accept a charge) and assists in starting the dead vehicle. The reason this helps in most cases with consumer jumper cables and another vehicle is supported by your example of a heavy duty commercial jump start device with very large (low resistance) cables and large power source. Consumer jumper cables (and jump packs) are limited in their ability to provide a large surge (cranking) by the total resistance between the jump battery and the dead battery(s). Remember: the longer the cable, the higher the resistance. The smaller the gauge of the cable, the higher the resistance. Jumper cable clamps are not so great for resistance either. That's why a battery post has so much contact area.
I respect (and agree) with your conclusions in part. As stated, and to your point, I think and agree that the waiting period provides basic charge to the battery in need and perhaps allows the cranked donating charge vehicle's alternator to charge its battery from diminished power it may have recently experienced from its own potentially recent crank.

To restate, in the 2018 3.6L JL this waiting period appears to have had a 3rd purpose: to provide a basic charge to the ESS/Aux battery, hooked in parallel to the main battery when the rig is at rest--as minimal charge in this smaller battery all on its own, from testing discussed on the forum--appears to be a necessary prerequisite for the vehcile to proceed, successfully or not, with attempting a crank whose power has been shown to be sourced from both batteries.:)

Videos showing how this 2018 year's JL can crank solely from its ESS battery, but not solely its main battery support these findings. And again, this doesn't seem to be the case for 3.6L JLs from 2019 and beyond. It may not even be the case any more in the 2018's if logic downloads from FCA to the rig altered the cold crank procedure.
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