Battery issues and How to test 48V eTorque Battery?

[Cujo7240]

I have 2019 Wrangler JL with the 20.0L eTorque engine and I have had battery charging issues for many years. While driving around town my voltage gauge states that it's charging at 14.4V all the time, but my starter battery keeps becoming discharged every week. I began a process of recharging my battery completely (12-9-13.0V) on the weekend only to find it at ~50% SOC (12.1 - 12.2V) after 1 weeks time. I drive my Jeep about 44miles a day, Monday thru Friday. Back in 2021 I installed a new Duralast Platinum AGM battery thinking it was a bad battery, but I'm still having the same issue now. I bought a separate voltage tester to go in the 12V power socket and it verifies the 14.4V charging voltage. I looked for any unusual parasitic current draws, but nothing seemed excessive. I was thinking the 48V battery may be at fault, but I don't know how to test it's voltage. Anyone know how to test the frame mounted 48v aux battery voltage?
I brought the Jeep into the dealer about this issue and they said everything checks out Ok.

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[The Last Cowboy]

Welcome to the forum. Sorry, but I gotta ask. Are you absolutely sure you have the 48V eTorque system? I was talking to a guy a few weeks ago and he was telling me how much he loved the 2.0/eTorque combo. We were looking over his Jeep, as he described the same issues you are having. Once he opened the hood it was apparent that he did not have eTorque, just the troublesome ESS system.

 

[limeade]

IIRC, the only 2019 JL's with the 2.0 eTorque were the Rubicon Recon models. @Cujo7240 you can verify if you have eTorque by looking under the driver side and seeing if there's a skid plate there. This skid will run lengthwise (parallel to frame rail) near the rear drive shaft. The skid plate on the passenger side is for the fuel tank. If there is no skid plate on the driver side, then you don't have eTorque and your electrical/charging problems are probably due to a bad ESS battery, which is under the 12V main starting battery.

If you do have eTorque, then I would suspect the Belt Start Generator (BSG) is not functioning correctly. The BSG performs multiple functions, one of them is to act like an alternator and charge the main battery. I've not heard of any way for a "shade tree mechanic" to test the 48V eTorque battery. I'm guessing it would take specialized tools and knowledge. The eTorque system is covered by an 8 year/80k mile warranty, probably best to find a different service department to check it out.

 

[Cujo7240]

Welcome to the forum. Sorry, but I gotta ask. Are you absolutely sure you have the 48V eTorque system? I was talking to a guy a few weeks ago and he was telling me how much he loved the 2.0/eTorque combo. We were looking over his Jeep, as he described the same issues you are having. Once he opened the hood it was apparent that he did not have eTorque, just the troublesome ESS system.

Absolutely positive that I have the eTorque 2.0L engine. I've also verified the frame mounted 48V battery and the additional battery cooling reservior underneath the hood.

 

[whitechocolate]

Absolutely positive that I have the eTorque 2.0L engine. I've also verified the frame mounted 48V battery and the additional battery cooling reservior underneath the hood.

Take video of when it happens and what the dash is doing. Post video here and take it to the dealer with video too,
do you have accessories ?

 

[Cujo7240]

Take video of when it happens and what the dash is doing. Post video here and take it to the dealer with video too,
do you have accessories ?

Take a video when what is happening? I'm so used to having discharge issues with my 2019 Jeep Rubicon JL with 2.0L eTorque engine, that I check the battery voltage every weekend. I always find it in a discharged state and I then attach my Optimate smart charger to bring it back to 100% SOC. Before I got into this routine I did get some error msgs like "Auxiliary switches have been disabled due to low voltage". On another occasion my key fob stopped working and when I tested the battery voltage it was down to 12.1V. Charged the battery and everything was working again. I even tested the Voltage of the key fob battery and it was good as well. I then aloud the battery to discharge until the key fob didn't work again and brought the Jeep to the dealer, so that they could diagnose the issue. They charged the battery on the Jeep and tested the battery and charging system, and replaced my key fob battery and said everything was just as it should be!

So, if everything is as it should be, then why does my battery drain down to 50% SOC every week after being charged?
I decided to charge up battery tonight, so that I could retest it with my Foxwell battery tester. The battery tested out as:

So my 2 year old Duralast Platinum battery is not the problem, but if I hadn't kept up my weekly charging efforts, it most certainly would be dead now.

You'll have to take my word that I have the eTorque 2.0L engine, since I don't plan to go under my Jeep to take a picture of it to prove it to you. I've seen and touched the metal enclosed battery box and skid plate and have followed the cooling lines from this location to the front of the vehicle.

It is my understanding that BSG unit charges the 48V battery and the 48V battery is supposed to then charge the 12V starter battery.
After confirming that my charging system had 14.4V during my commute today, I was all set to go out and buy another battery., but after tonight's battery testing results showing that the battery is good, I'm not sure what else it could be. That is why I was looking for a way to check the 48V battery Voltage. I was thinking there should be some test points I could probe with my DVM.
I would also have to believe that the BSG is good, since I'm getting 14.4V with the engine running.

 

[smokeythecat]

How did you check for parasitic current draw? Did you put a meter in circuit with the battery cable? If the current doesn't settle down to about 0.3A after a couple of minutes there might be something draining your battery. I throw out that number because that's what I saw on my 3.6L eTorque engine.

 

[Cujo7240]

How did you check for parasitic current draw? Did you put a meter in circuit with the battery cable? If the current doesn't settle down to about 0.3A after a couple of minutes there might be something draining your battery. I throw out that number because that's what I saw on my 3.6L eTorque engine.

I used an inductive amp clamp style multimeter to look for parasitic draw where it was feasible. Many of the positive cables leaving the battery are grouped together into a single harness, which makes using the inductive amp clamp method difficult if not impossible. I may need to install may multimeter in series with the positive cable and battery to get a better measure of the parasitic draw.
Using the inductive clamp meter I was able to determine that none of my installed accessories were not the issue.
If I remember correctly, I measured about a 0.6A parasitic draw on the negative battery cable.

 

[4a4c55]

I measured about a 0.6A parasitic draw on the negative battery cable.

But isn't 600 milliamps very high? If your Jeep has gone to sleep, I think you should see less than 100 milliamps. It's quite hard to measure parasitic draw on modern cars because they'll wake up and go to sleep for all kinds of different things.

From the symptoms you've described, you've either got a parasitic draw or you're not actually charging in the first place.

 

[Cujo7240]

But isn't 600 milliamps very high? If your Jeep has gone to sleep, I think you should see less than 100 milliamps. It's quite hard to measure parasitic draw on modern cars because they'll wake up and go to sleep for all kinds of different things.

From the symptoms you've described, you've either got a parasitic draw or you're not actually charging in the first place.

I bought a plug in DC voltage gauge to monitor the voltage while driving. The voltage starts out lower before I start the Jeep and after starting it goes up to 14.4V. According to my battery tester my battery is in great shape. So I'm left with parasitic amperage draw as the only possible cause. I was hoping someone here would know where some voltage test points were for the 48V battery, so that I could verify it's SOC. From what I've read the generator charges the 48V battery and the 48V battery then charges the 12V battery. If this is indeed the case it must be working, since I'm monitoring 14.4V while the engine is running.
I installed an aftermarket solar panel to my Jeep and it has helped (See attached picture). Normally I would start out the week with full charge of 12.8V + and usually by the following Saturday the Jeeps battery voltage would be down to 12.2 to 12.3V. Now with the solar panel system installed the battery voltage measured 12.5V this last Saturday.
I need to spend some more time to see if I can track down where this parasitic draw is coming from. I've already ruled out the accessories that I've added as the cause by measuring for current flow when the Jeep was off. Besides, I was having this battery draining issue before any of these accessories were added.

 

[BrierPatch]

The only suggestion I can come up with right now would be: Put an amp meter on it and monitor the current draw and start removing fuses 1 by 1 in some kind of organized fashion and see when the current drops.

I'm curious about how the 48v battery charges the 12V. I would think it would be charged by the BSG and not from the 48v battery.

 

[azwjowner]

The only suggestion I can come up with right now would be: Put an amp meter on it and monitor the current draw and start removing fuses 1 by 1 in some kind of organized fashion and see when the current drops.

I'm curious about how the 48v battery charges the 12V. I would think it would be charged by the BSG and not from the 48v battery.

No need to remove fuses. I'd wait for the electronics to settle and then just measure voltage drops across the fuses, in conjunction with this table: https://www.meeknet.co.uk/E64/Fuse Voltage Readings To Give Current Readings.pdf

 

[4a4c55]

I was hoping someone here would know where some voltage test points were for the 48V battery, so that I could verify it's SOC.

I don't know of any. I've asked a couple questions about troubleshooting and maintaining the eTorque system here, but I haven't gotten any good answers at all. It doesn't seem to be particularly well documented.

just measure voltage drops across the fuses,

This can work for a coarse measurement, but the table assumes certain values for the resistance of the fuse. Since that can vary (and by a lot, since it's such a small number) these measurements are quite coarse. It's a good first step, tho -- to find the circuit that's using the most current without pulling fuses that could cause the vehicle to wake up again.

 

[Cujo7240]

Thx for all of your suggestions!

 

[4a4c55]

Thx for all of your suggestions!

Happy to try to help ... please do let us know what you find!

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