3.6L Alternator/Battery Charging

redsyphon

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I've been monitoring the battery on my JLUR 2018 for some time now as I've noticed it's always at 13.9 to 14.1 volts while driving (even on long trips).

I've been doing this for the past 2k miles / 1.5months.

This morning was our first cold snap (Florida) at around 37deg F. After a 30 minute drive to work, the display still showed 14.6

Would this be an indication the battery(ies) aren't holding a good charge? Or perhaps a bad voltage regulator assuming that's how the alternator is being told when to ramp up/down?

This is my second JL. My old Sport would start at around 13.8 and drop after some driving (30 -1hr) to 12.8 to 13.2 area.
20201201_084950-01.png

 

OldGuyNewJeep

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I've been monitoring the battery on my JLUR 2018 for some time now as I've noticed it's always at 13.9 to 14.1 volts while driving (even on long trips).

I've been doing this for the past 2k miles / 1.5months.

This morning was our first cold snap (Florida) at around 37deg F. After a 30 minute drive to work, the display still showed 14.6

Would this be an indication the battery(ies) aren't holding a good charge? Or perhaps a bad voltage regulator assuming that's how the alternator is being told when to ramp up/down?

This is my second JL. My old Sport would start at around 13.8 and drop after some driving (30 -1hr) to 12.8 to 13.2 area.
20201201_084950-01.png
This has been discussed a lot. At a minimum, please read this thread: https://www.jlwranglerforums.com/forum/threads/3-6l-ess-dual-battery-consolidated-information.25377/

Some vehemently argue that 14+ reading means you have a failing battery or batteries. Others, like me, say it’s normal. Mine has read 14+ since day one of ownership. I’m at nearly 36,000 miles and 2.5 years of ownership. I put my batteries on a tender several times a month. I have never had an ESS error or a dead battery.

By the way, my 2016 GMC Yukon XL with a one week old battery also reads 14+ volts regardless of how long a road trip we take; it always has.

Grab a $50 Deltran battery tender and keep your batteries well maintained. No harm in having your batteries tested in isolation, if you’re worried.
 

HoboJeep

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I think you are OK. On my daily short drive to work (12 miles) mine is almost always over 14V. This morning it was 14.5. It was cold here too (NC) and I thought that may have had something to do with it. I check mine regularly also. Just turned 15,000 miles. Only time it gets into the lower 13 range is when I drive for long periods of time (couple of hours maybe).
 

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I noted very high voltage readings last year. Then Stop/Start would not work. Later, it was difficult to start the engine ... lack of battery juice. Later, I had to jump start the JLUR 2018 to get it to the dealer ... hoping the engine would not die.

The dealer said they've seen this before and they've been told to replace the batteries ... so bad batteries. Everything work after that. After the batteries got replaced, I have voltage readings in the 12 to 14 VDC range. THen the voltage started to creep up again. Jeep said this was normal.

Moral of the story: make sure you have jumper cables in case the batteries die. lol :)
 

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My experience on hundreds of other vehicles, but none of them jeeps is the following. 12.7 ish vehicle off battery voltage reading. 13.5-14 battery reading at idle, and up to around 14.7 battery reading while driving /increased RPM. My last Chrysler vehicle (Charger) also had built in over volt protection. I installed an alternator, and randomly everything would shut off for a second and then come back on as I was driving. Testing charging volts everything appeared fine. Finally determined that as the diodes were heating up they were momentarily allowing voltage spikes of up to 16v to pass and the computer was shutting down until the spike passed, preventing the charge from frying it. I don't believe I would be worried about 14.5 ish volts.
 


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redsyphon

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Thanks for the feedback all. I had and continue to follow some of the other related threads. The progressive increase on top of the sudden spike to 14.6/7ish is what had me worried.

I do carry a jump pack in the Jeep at all times, so that does provide some insurance. Only as long as the batteries hold charge post start though.

I'll stick to my plans to swap out to the Genesis Dual Battery system in the Spring and sit tight until then.

If she starts acting weird, then I'll get her load tested. Hopefully that's never an issue.
 

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redsyphon

redsyphon

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That won’t help you unless you also carry a fused jumper wire so that you can bypass the aux battery. Search forum for “N1 N2”
Already ahead of ya :)

I've had a 30A fused cable in the glove box for the past year. It sits right next to a replacement fuse array for the those connects. P/N 68368853AA
 

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If you don’t use ESS you can run a jumper to N1 and N2 and disconnect the ESS negative off the main, you won’t get any error messages, don’t use ESS with this setup as doing so will tax the main crank battery.

I personally went to a dual battery system ( Genesis ) and have zero regrets, my electrical system seems so much happier with the added full size battery plus I have a so to speak built in jump pack
 
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redsyphon

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A quick update for this afternoon. On the way in this morning, the Jeep showed the "ESS not available... battery charging." message.

It was only a 20 minute drive and voltage held at 12.8 with engine off, so I parked and went about things as normal.

Come to 8hrs later, and I ended up jumping the Jeep with the power pack (glad I had it) to get her going again.

14.7 volts the whole way home and no ESS.

I've gone ahead and ordered the @Genesis Offroad System w/batteries to replace my current ones.

I was hoping to hold off a while longer, but the Jeep seems to have different plans.

I think the telling sign should have been the ESS message, but I only noticed that this morning. Had it stayed around 14 without other messages; I think all would have been well as others here and different threads have stated.

Oh well, now I know more... and I finally got to use my jumper :)

I'll be curious to see how the voltages show with the Genesis System in place.
 


WranglerMan

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@redsyphon when you get the Genesis system in I would suggest you get a decent higher end smart charger like a NOCO 10, NOCO G1500, Odyssey 12 or Odyssey 20 and fully charge you batteries after the install, not sure where you got the Genesis system from but my batteries needed a full charge after mine was in, I went with Full River 750-25’s

Your Jeep will start easier and crank faster with the larger full size battery, mine has been in for awhile and I have zero issues

If you get bored and need something to read here is my non scientific review, I am no affiliated with Genesis Offroad, NOCO or Odyssey and receive nothing for giving them kudos but so far my system is running perfect but if you choose not to read the below the down and dirty on the voltage is if my JL sits for a day or two off my charger the voltage on each battery is usually in the 12.55-12.65 range and my review describes why the voltage is this low after being parked but within 30 mins of driving they are back to the 12.8+ range so my voltage usually after parked for a day or two displays 14+ on the EVIC but that voltage is influenced by the alternator and after 30 mins of driving it drops to the 12.9-13.1 range so the smart charging system is doing what it’s designed to do.

One thing to understand is if you use ESS you are limited to (6) cycles and then ESS is disabled, this is not a Genesis issue this is built into the logic of the JL as when it see two voltages that are the same it assumes there is an issue so it disables ESS but I don’t use ESS so all I have is the dual system with what I call a built in jump pack

https://www.jlwranglerforums.com/fo...ll-by-tank-customs-and-charger-testing.61493/
 
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redsyphon

redsyphon

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@redsyphon when you get the Genesis system in I would suggest you get a decent higher end smart charger like a NOCO 10, NOCO G1500, Odyssey 12 or Odyssey 20 and fully charge you batteries after the install, not sure where you got the Genesis system from but my batteries needed a full charge after mine was in, I went with Full River 750-25’s

Your Jeep will start easier and crank faster with the larger full size battery, mine has been in for awhile and I have zero issues

If you get bored and need something to read here is my non scientific review, I am no affiliated with Genesis Offroad, NOCO or Odyssey and receive nothing for giving them kudos but so far my system is running perfect

https://www.jlwranglerforums.com/fo...ll-by-tank-customs-and-charger-testing.61493/
Thanks for the heads up.

I ordered the batteries straight from Genesis Offroad as a package to make it simple, etc.

The models are indeed Fullriver FT750-25
 

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Thanks for the heads up.

I ordered the batteries straight from Genesis Offroad as a package to make it simple, etc.

The models are indeed Fullriver FT750-25
Like I said not sure if you use ESS but there is a (6) cycle limit, during the install the ESS positive is moved to the main crank battery and both ends of the ESS negative are not used so the JL‘s ESS system sees both batteries voltage as the same so it assumes there is a problem and it disables ESS until the ignition is cycled then the count starts over, I have ESS disabled using a Smart Stop/Start module as I truly dislike ESS but I dislike the location of the ESS battery more but I won’t go into that.
 

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A quick update for this afternoon. On the way in this morning, the Jeep showed the "ESS not available... battery charging." message.

It was only a 20 minute drive and voltage held at 12.8 with engine off, so I parked and went about things as normal.

Come to 8hrs later, and I ended up jumping the Jeep with the power pack (glad I had it) to get her going again.

14.7 volts the whole way home and no ESS.

I've gone ahead and ordered the @Genesis Offroad System w/batteries to replace my current ones.

I was hoping to hold off a while longer, but the Jeep seems to have different plans.

I think the telling sign should have been the ESS message, but I only noticed that this morning. Had it stayed around 14 without other messages; I think all would have been well as others here and different threads have stated.

Oh well, now I know more... and I finally got to use my jumper :)

I'll be curious to see how the voltages show with the Genesis System in place.
What was the no start behavior, slow crank, no crank, dead electronics?
 
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redsyphon

redsyphon

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What was the no start behavior, slow crank, no crank, dead electronics?
Slow crank first two tries. Let her sit (30 seconds), just a click after that.

Inside electronics were on, but no error codes. I scanned for codes after getting her started with my odb2 reader, but nothing was thrown.

I did not try a crank after jumping N1 and N2 (maybe I should have).

Addition/edit: I did let her sit for roughly 2.5hrs after getting home. She started up and I drove for roughly 30 minutes. Still same voltage and ESS status, but there's no delay on crank at the moment. I'll see what it does in the morning.

 

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