Drained Battery, Any jumpstart tips??

[CoolToys]

Found the N5 post in the main fuse box. Still didn't help, too tight for jumper cables but put the charger straight to it.

Sponsored

 

[Gee-pah]

Having the same issue and read all through the thread and realized I can't find the N5 post. So here I sit with trickle charger connected. This is not something I would recommend for taking way out in the woods, and the scary part is I already have.

For those of us without the Chilton manual, where is this mystery N5 post? Any chance of a photo?

Next, if Jeep is reading this:
1. PLEASE PUT IT IN THE MANUAL THAT STANDARD JUMP STARTING DOES NOT WORK.
2. Please fix the issue. Why do you build a vehicle with two batteries that can't sit more than a week? I am on the road often for three or more days at a time. My other two vehicles like this can sit months without sitting on a trickle charger. When the vehicle is not in use the ESS battery (or whichever you decide to use to start) should be isolated so it holds voltage. That way my manual key still works to get in.

Hey Scott:

Let me see if I can tackle your issues one at a time. What I'm about to say pertains to the 3.6L JL.

If you open and pop up your hood and look by the passenger's side, closest to the fire wall expect to see a black plastic rectangular box on the highest point under the hood.

It has two latches keeping its top on, one closest to the front of the rig, and one on the backside of the box. If you press those in with your fingers you can lift the top of the box open. That thing is your PDC or Power Distribution Center.

Once open, on its right side is a bunch of fuses in a straight line, front to back of rig. They're sometimes known as the high order fuses as they break some of the largest amperages in the rig. The 5th one from the front of the rig is N5.

Blow any of these fuses and you have to replace the entire line, but you do NOT need to replace the entire PDC.

~~~~~~~~~~~~

That strictly answers your question but by no means gets to the real heart of the matter.

If your ESS/Aux battery lacks power the rig won't crank. If you are stranded and have but a small portable jumper pack with you, (along with a wrench) the greatest chance you have of getting the rig going in such failures is to disconnect all the black wires that lead to the main battery temporarily.

With these wires dangling in mid air, away from the main battery's negative post, clip your negative lead from the power pack on to these dangling wires and the postive side to the main battery's positive post and try cranking ASAP.

If you are able to crank the rig, CAREFULLY put those negative cables back on the main battery's negative post.

~~~~~~~~~~~~~

At this point I could go to great lengths on why this is the case but have done so, as have others in other posts. LSS, you just direct connected to the ESS/Aux battery and ONLY that battery.

1. PLEASE PUT IT IN THE MANUAL THAT STANDARD JUMP STARTING DOES NOT WORK.​

My friend Scott, FCA already has (NOT).

What they've actually done is explain that jump starting a 3.6L is not standard by vitue of your need to keep the jumper cables on the main battery for a length of time before attempting a crank.

Maybe you need to understand why and don't. Once the concept is mastered you'll appreciate why this technique is the worst you could follow if in the middle of nowhere with a small power pack, and why the method I suggest is better in these circumstances.

99% of the time the two batteries in your rig are connected in parallel, including when the rig's at rest. The whole purposes of the stupid procedure in the manual, involving hooking your jumpers up the main battery is for purposes of charging the ESS/Aux battery--which happens BECAUSE the two batteries are connected in parallel when the rig's at rest.

That ESS/Aux battery must have power all on its own or the rig won't even attempt a crank. But while doing this manual procedure you are also charging the main battery, depleting the jumper pack of cranking power and charging a battery you don't need to crank (the main one that is.)

This is waiting time is fine if your jumping source is another vehicle's battery, but is a counterproductive method for small jumper packs.

Truth be told, disconnect the two batteries and you can run just fine with an energized ESS/Aux battery, but the opposite is not true. The rig will tap both batteries for the crank if they are available, but not even attempt that crank if the ESS/Aux battery, testing on its own by the rig, is dead.

2. Please fix the issue. Why do you build a vehicle with two batteries that can't sit more than a week?

Answer: IMHO, because FCA wanted to save money and didn't think this through.

Let me see if I can explain that one.

Once your rig is successfully cranked, the rig never needs to worry about the ESS/Aux battery. If it has too little power, ESS events won't occur. Or if ESS events occur and deplete this battery, the rig will recrank before the ESS/Aux battery dies, even if the ESS event ends prematurely.

What the engineers did is copy this model for cold cranking, and IMHO screwed up. What they should have done for cold cranks is...if the ESS/Aux battery is dead, to see if the main battery has enough juice to get the rig going....NOT fail attempting a crank just because the ESS/Aux battery is dead.

If it makes you feel any better I wrote to Mike Manley, then President of FCA not only about this, but how to fix it.

Fortunately, one of our posters already has--somewhat.

https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/

This hack keeps the two batteries in parallel 100% of the time. Your rig will start even if your ESS/Aux battery is dead.

The only downside to this brilliance is that the rig sees the ESS/Aux battery and main battery as one, and may enter into ESS events when the ESS/Aux battery's power alone would have prevented this, or keep them running too long as a result.

If you never engage ESS, this isn't an issue.

You see the whole idea of running ESS events off a separate battery is so the main battery keeps charged to re-crank the engine. With this hack it too is taxed during ESS events.

There's a lot here, and I've skimmed believe it or not. Hit me up with questions if you wish.

​

 

[Gee-pah]

Found the N5 post in the main fuse box. Still didn't help, too tight for jumper cables but put the charger straight to it.

Get to the ESS battery my way Scott. It's too hard to isolate N5, and screwing up any of the NX fuses means having to replace the entire line of them.

 

[Jebiruph]

Found the N5 post in the main fuse box. Still didn't help, too tight for jumper cables but put the charger straight to it.

N5 was misidentified as the ESS battery early on, the label under your PDC lid says it's the RAD FAN, so it's obviously where many posters on this forum get their energy.

The good news is, based on the wires connected to your PDC, you have a BSG system and not the ESS system, so none of this dual 12v battery foolishness applies you.

 

[Jebiruph]

You see the whole idea of running ESS events off a separate battery is so the main battery keeps charged to re-crank the engine. With this hack it too is taxed during ESS events.

Since the battery sensor is constantly monitoring the status of the main battery, I would expect any ESS event running solely on the main battery or not, to be terminated before the main battery is too taxed.

 

[CoolToys]

Gents,

Thank you for all of the information. To start, my JLU is a 2019 2.0t mild hybrid. I used a volt meter and played around in my fuse box aka PDC, and found N1,3,5 and 8 all on the same bus. There is clearly something that isolates the two batteries at some point.

The main battery was down to 1.3V and the N1,3,5,8 posts read 3.2.

The owners manual only says to connect jumper cables to the other car first and it should not be running. Nothing about dual batteries anywhere. Jeep is clearly shipping a beta product. That is ok for a cell phone, not so much for something I trust to take me hundreds of mikes from civilization.

Jeep Wave was useless.

Right now I have a single trickle charger and have given up on it for the day. If it won’t start in the morning the dealer can tow it in.

 

[Jebiruph]

Gents,

Thank you for all of the information. To start, my JLU is a 2019 2.0t mild hybrid. I used a volt meter and played around in my fuse box aka PDC, and found N1,3,5 and 8 all on the same bus. There is clearly something that isolates the two batteries at some point.

The main battery was down to 1.3V and the N1,3,5,8 posts read 3.2.

The owners manual only says to connect jumper cables to the other car first and it should not be running. Nothing about dual batteries anywhere. Jeep is clearly shipping a beta product. That is ok for a cell phone, not so much for something I trust to take me hundreds of mikes from civilization.

Jeep Wave was useless.

Right now I have a single trickle charger and have given up on it for the day. If it won’t start in the morning the dealer can tow it in.

Your system is the BSG system and has a 12 V battery and a 48 V battery for the mild hybrid. Most of the battery discussions that I see are about the ESS system that has 2 12 V batteries. I can't give you any help with your system, but would like to here what you eventually find out.

 

[Gee-pah]

Since the battery sensor is constantly monitoring the status of the main battery, I would expect any ESS event running solely on the main battery or not, to be terminated before the main battery is too taxed.

I hope you're right Jerry. I have not tested it. But in theory there'd be no reason for the rig to test the main battery during an ESS event as it's normally, barring your jumper hack, not being taxed by the rig's appliances during an ESS event---barring whatever accessories an owner may have directly connected to it.

 

[Jebiruph]

I hope you're right Jerry. I have not tested it. But in theory there'd be no reason for the rig to test the main battery during an ESS event as it's normally, barring your jumper hack, not being taxed by the rig's appliances during an ESS event---barring whatever accessories an owner may have directly connected to it.

It's always monitoring the status of the main battery, there's no reason to stop for ESS. Try turning your wheels during an ESS stop. If you turn them enough, the engine will start, the power steering pump is running off of the main battery.

 

[CoolToys]

Your system is the BSG system and has a 12 V battery and a 48 V battery for the mild hybrid. Most of the battery discussions that I see are about the ESS system that has 2 12 V batteries. I can't give you any help with your system, but would like to here what you eventually find out.

So I had not thought about the voltage difference of the two batteries. but 12V into a 48V battery shouldn't hurt it. After thinking back (Ok my wife reminded me), I realized a few things about the hybrid battery.

The Death Spiral

After 48 hours of sitting the automatic start/stop quits and I get a "auto start disabled, battery charging" indication on the dash. I have learned to ignore this because it sits every weekend and any time I am on the road.
After 3-4 days of sitting, it did not start twice, but I did a normal jump start, one with my back up compressor battery, one with a roadside truck.
It is after more than 4 days of sitting it will not start even with a jumper. This is the second event. First time I was at the shop and had the big rolling battery rig which got it up to 11V in about an hour and it started with the boost on.

Current Sit Rep

Still dead, swapped battery maintainer for charger, going to attempt another jump start in an hour or so. Again i can't find anything in the manual about the 2.0t mild hybrid system. Owners manual looks like it belongs to a 1984 CJ. And I have a slush box so the push start is out.

My guess is there is a step up between the batteries of some kind, and I wonder if you can even charge the 48V via the 12v without some big amps pushing across.

Since it has been on the trickle charger (oops maintainer) all night, I went out and measured the voltages again.
N1 3.1
N3 3.4
N5 3.4
N8 3.4

Main Battery 3.6

What? Yes I did check the voltmeter on the jumper kit and the jag diesel it works, Jeep don't.

Now that it is daylight I have hooked up a larger charger to see if it will help. It almost acts like it is drawing faster than the batteries can charge. If this charger won't do it I am on the fence of putting the big charger in my wifes jag and bringing it home or letting Jeep tow it away. My dog will bite me if she sees another one of her Jeeps get towed away so I am hoping to avoid that.

Possibly a second day of filming and surfing lost. Was someone looking at the eco diesel or the Land Rover?

 

[Gee-pah]

N5 was misidentified as the ESS battery early on, the label under your PDC lid says it's the RAD FAN, so it's obviously where many posters on this forum get their energy.

The good news is, based on the wires connected to your PDC, you have a BSG system and not the ESS system, so none of this dual 12v battery foolishness applies you.

I think this N5 leading to the ESS battery misnomer Jerry may have its origination (or at least early origins here.)

 

[Gee-pah]

I talked prior about the easiest way to test the ESS/Aux battery on a 3.6L JL is, with engine off, is to temporarily yank the negative cables off the main battery post, and put your tester's negative side to these dangling cables, and its positive side to the main battery's positive post.

IMHO the best way to facilitate quick jump starts in the 3.6L is to buy an Anderson hook up to eyelits cable like this:

https://www.polepalsolarlightingsys...ndard-size-winch-2-ga-wire-0.364#.Xh4TXndFy1s

Put the positive on N1 (and ONLY N1) in the PDC. The negative can go on the main battery's negative terminal. (You may have to bend the positive eyelit 90 degrees to get the PDC cover to close.)

Then get an Anderson hook up to alligator clips cable. It looks like the shorter cable here on the right. This vendor will sell you cables of any length with anything on the ends you want (eyelits, Anderson connectors, alligator clips, etc.)

If your rig won't crank, temporarily connect the two cables at their Anderson connectors and the alligator clips to those of a working power source and crank.

You've direct connected to the ESS/Aux battery. Try cranking as soon as you'd like.

Put the Anderson connector to alligator clips cable away thereafter.

 

[CoolToys]

Andy and Jerry,

Thanks for the insights but I have given up, this goes back to the dealer. Roadside assistance on its way.

The big battery tester/charger/jumper from the shop says there is an error, so I don't want to risk doing anything to make it worse or void the warranty.

All I am thinking is I should have held out for the diesel. The sad part is I really was starting to like this one and get over it's over gentrification. 24+mpg was great even if I did have to buy premium and have hard plastic covering the roll cage.

I will put a meter to all the posts when (if) I get it back from the dealer.

 

[CoolToys]

All,

I have not yet put a meter on all the posts, but....

Roadside assistance showed up in a Prius. He pulled out a Dewalt 1400cca jump starter, and nothing. He paralleled a 2nd one and said "these new ones take a lot of juice". We waited two or three minutes and then it started. The interesting thing is that he kept it all hooked up for another five minutes so it would not die. The voltage was 13.4 and 13.2 on the screens when he connected them. The Jag put out 12.9 when I tried to use it for a jump, and my big battery was at 12.5. I never thought to parallel them. That is a lot of amps.

He also claimed that the Jeep could recharge both of the Dewalt portable batteries. I doubt it as I am sure they are diode protected, but it is possible.

It took about thirty minutes to get the start stop battery indication to go out and everything is good. I will test all poles after the morning surf session..

I may have a bad cell. After an hour of driving it around, the big charger jump starter still showed "error" and would not supply power.

There is another thread were a guy built a really cool battery maintainer platform.

https://www.jlwranglerforums.com/fo...arger-mount-inlet-install-lots-of-pics.44466/

This might be my next step, although I think I'll just run the extended pigtail and leave the transformer in the garage.

If it won't start in the morning for the surf session, I'll go with one of the many batteries having a bad cell. Otherwise, I am sticking to bad design on FCA part to drain batteries while it sits.

Cheers

 

[CoolToys]

SitRep

JLU started this morning just fine.

One thing I did not mention is that the entertainment system went completely stupid when we got it started. After an hour and several shutdown/restarts it did not fix so I called Jeep Wave service. They only said "take it to the dealer". Half way to the dealer this morning, I stopped for a soda, and when I restarted the entertainment system flashed and was back to normal.

Voltages for a 2.0t Mild Hybrid when not running below. I don't detect anyplace the 48V connects to the PDC, at least not when off.

N8 12.3
N7 - N/A
N6 0
N5 12.3
N4 0
N3 12.3
N2 12.3
N1 12.3

Main Battery 12.4

Apparently the answer is not one but TWO 1400CCA batteries in parallel to start the thing. No Idea why the big battery tester gave an error, today it shows full charge, and past the 1 hour load test.

Sponsored