Drained Battery, Any jumpstart tips??

[Rusty Teeth]

1st night had jl, morning dead.
Found N1 and N2 with very low voltages.
Dont recall exactly like 11.1 and 4.2
Under the fuse box has these identified.
Next day dealer replaced ess relay.
Still had problems untill i trickle charged both. Still not sure how to jump start.
Also every fuse was loose, had to seat every one of them. Including relays
Futher inspection shows a distribution wire touching. Just fyi. Subject has been addressed under wont start threads.
Hope this helps. Sorry hard to be more articulate, typing on my phone. See pix!
Frank

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[old8tora]

What did you have connected that was able to drain the batteries in a single night?

 

[old8tora]

what did you have plugged into your rear 12 volt that drained your battery????

 

[Rusty Teeth]

I think the software allowed the jeep to be left in drive and if you hit the stop push button. It put the jeep into ACC position and kept most things alive.
I now see that if I try to duplicate that, I get the shift indicator to flash fast and a ding ding ding, when I try to exit. Must have been a flash update.
some of these updates, have pages of little things that get updated.

I asked the dealership, how do I jump start this jeep. They thought like any other car. (dont think this is true)

See small battery sensor on positive terminal that feeds battery under the battery. Its an interesting set up

 

[RussJeep1]

Why couldn't if need be, leads be attached to the ESS battery that when necessary, connect to your jumper cables?

 

[digitalbliss]

It's been shown that without the Aux battery, the Jeep will not start. Disconnect the main battery but leave in the Aux and it will start. That tells me that you need to hook up the jumper cables to the Aux battery.

 

[old8tora]

Very difficult to believe that a JL cannot be jump started ? Attach cables to a running Ram and I'll bet it will start .

 

[Jebiruph]

Based on the schematic in this post, https://www.jlwranglerforums.com/forum/threads/aux-battery-wiring-diagram.7438/, here's my observation about how the dual batteries work. Please feel free to provide additional information or corrections as you feel necessary.

I don't see any direct connection between the positive terminals of the two batteries, they are connected through the Power Control Relay. The Keyless Ignition Node and Radio-Freq Hub are powered by the Aux Battery, which explains why the Aux Battery is needed to start. It powers the Power Control Relay (through the Body Control Module), which puts both batteries in parallel, thus connecting the Aux Battery to the rest of the electrical system.

The schematic shows the Main battery connected directly to the starter. To jump start with a dead Aux Battery, I would connect the jumpers to the main battery with a secondary jumper to N1 (Aux battery) to power the electronics needed to start. If a secondary jumper isn't available, I would clamp the positive jumper cable to N1 (Aux battery) and N2 (Main battery) simultaneously.

Edited to fix incorrect terminal labels.

 

[1idrod]

Well I just saw this post and skimmed through it. I in fact did have my battery drain while sitting in my garage. Something was keeping the instrument cluster on along with the shift indicator lights. I didn't notice how long but my Jeep will sit for days sometimes and one day I went out to start it and it was dead. This happened to me twice. I first hooked up a charger to it with no luck but then I jumped it off of my truck. After about 5min I was able to start the Jeep. Like I said, this happened twice and after the second time something must have reset because the lights finally stopped coming on once the vehicle was shut off and haven't had any issues since but I was able to jump it the way you traditionally would.

 

[Rusty Teeth]

Based on the schematic in this post, https://www.jlwranglerforums.com/forum/threads/aux-battery-wiring-diagram.7438/, here's my observation about how the dual batteries work. Please feel free to provide additional information or corrections as you feel necessary.

I don't see any direct connection between the positive terminals of the two batteries, they are connected through the Power Control Relay. The Keyless Ignition Node and Radio-Freq Hub are powered by the Aux Battery, which explains why the Aux Battery is needed to start. It powers the Power Control Relay (through the Body Control Module), which puts both batteries in parallel, thus connecting the Aux Battery to the rest of the electrical system.

The schematic shows the Main battery connected directly to the starter. To jump start with a dead Aux Battery, I would connect the jumpers to the main battery with a secondary jumper to C5 (N5) to power the electronics needed to start. If a secondary jumper isn't available, I would clamp the positive jumper cable to C5 and C6 simultaneously.

 

[Rusty Teeth]

On the fuse cover it lists N1 and N2 as the main and aux batteries.
When i had a no start condition had 11.3 on N1 and 4.2 volts on N2 only after slow charging both was i able to get it to start.
If you look closely at the pix posted, i has N5 and N6 terminals touching and tab on terminal not seated in groove.
After ess relay was replaced. Had 13.2 and 13.8 on main and aux battery after good trickle charge.
I did reseat the touching terminal properly.

 

[Jebiruph]

Well I just saw this post and skimmed through it. I in fact did have my battery drain while sitting in my garage. Something was keeping the instrument cluster on along with the shift indicator lights. I didn't notice how long but my Jeep will sit for days sometimes and one day I went out to start it and it was dead. This happened to me twice. I first hooked up a charger to it with no luck but then I jumped it off of my truck. After about 5min I was able to start the Jeep. Like I said, this happened twice and after the second time something must have reset because the lights finally stopped coming on once the vehicle was shut off and haven't had any issues since but I was able to jump it the way you traditionally would.

First, it's sounds like you had a relay that was stuck closed, draining the battery. If it happens again, I would check the relays. Second, it's good to hear you were able to jump it the traditional way, but I wonder if that worked because the Aux battery still had a charge.

 

[Jebiruph]

On the fuse cover it lists N1 and N2 as the main and aux batteries.
When i had a no start condition had 11.3 on N1 and 4.2 volts on N2 only after slow charging both was i able to get it to start.
If you look closely at the pix posted, i has N5 and N6 terminals touching and tab on terminal not seated in groove.
After ess relay was replaced. Had 13.2 and 13.8 on main and aux battery after good trickle charge.
I did reseat the touching terminal properly.

Thanks for the clarification. I had watched a video that said terminal 5 connected to the Aux battery, which now I don't think is correct and I'm trying to figure out the best way to to deal with my incorrect posts. I saw your post with fuse box label, but missed your description of what the label was and didn't pay enough attention to it.

 

[RussJeep1]

Thanks for the clarification. I had watched a video that said terminal 5 connected to the Aux battery, which now I don't think is correct and I'm trying to figure out the best way to to deal with my incorrect posts. I saw your post with fuse box label, but missed your description of what the label was and didn't pay enough attention to it.

With no disrespect intended to your findings Jebiruph, this was the YouTube video--maybe you the same--that lead me to believe that terminal 5, a.k.a. T5 in the PDS (Power Distribution Center) has a cable connected to it that leads directly to the smaller/auxiliary ESS battery.



With this in mind, I own a bunch of charging cables with either alligator clips or eyelids at one end, and quick disconnects at the other end. They look like this.

Yesterday I connected the smaller cable's positive to T5 in the PDS, and the negative to the main battery ground and left the cable under the hood that way.

I have no idea, should I run into a dead ESS battery, if hooking the larger cable to the smaller, and the alligator clips end of the long cable to a 12V DC source, dare I say, even my own main battery, will it allow the rig to start. Honestly, I'd rather not tinker with a $50K piece of gear to find out my answer and risk damaging things.

But if someone like Brandon Halon of Youtube's Jeep Informant, or Eddie Oh of [Banned Site] should ever confirm this, either because they've done their homework with FCA first, and/or have rigs to test with and confirm, it's good to go at my end.

I'm surmising, perhaps incorrectly, that it is the PDS which isolates terminal T5 in the PDS upon startup such that absent a charged ESS battery: which seems to be needed to crank the rig, it won't start, but otherwise joins the two batteries in parallel, at least when the rig is shut down or successfully cranked, to allow both batteries to charge when hooking up a charged battery to the main battery terminals when the rig is off, or the rig's alternator when the rig is running.

I wonder if, in the manual, where it recommends to allow the vehicle doing the jump start to idle a couple of minutes--presumptively to let its alternator max the battery's power before jump starting the JL (a task by the way that would normally come before cables were connected, dissimilar to the instructions) is really just "smoke and mirror" speak for giving the JL a few minutes to charge the ESS battery enough (with the rig off and the two batteries presumptively connected in parallel) to crank the engine, and that what really is going on is a few minutes of trickle charging only.

Again, perhaps this is wrong, and perhaps I'm caught up on semantics, but this isn't "jump" starting to my way of thinking, which is something I think of as capable of attempting the second after a dead rig is connected properly to an appropriate live energy source.

 

[Jebiruph]

With no disrespect intended to your findings Jebiruph, this was the YouTube video--maybe you the same--that lead me to believe that terminal 5, a.k.a. T5 in the PDS (Power Distribution Center) has a cable connected to it that leads directly to the smaller/auxiliary ESS battery.

Thanks for your input. Watch this video from Brandon Halon of Youtube's Jeep Informant, This shows that all those terminals except N1 are connected to main battery through fused connections. Basically, N2 - N8 connect to the same power distributing piece of metal. And read the label on the underside of the PDC, it labels what terminals N1 - N8 connect to. Your jumper to N5 is electrically connected to the main battery on N2. It should go to N1 to connect to the Aux battery. Reread Rusty Teeth's posts #31 and #41, I believe he confirmed N1 - Aux and N2 - Main based on his voltage measurements at those points with depleted and charged batteries. Feel free to point out any flaws in this post.

Edited to add reference to #41

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