Battery Voltage reading? What is normal?

Wranglerman

New member
I think some people were reporting that they have seen 12s and 13s while the Jeep is running. Maybe gecko can clarify, but it seems that the JL has electronics in between the alternator and batteries so it can disengage sort of, and not send a charge while the vehicle is running, allowing the running voltage to dip below the 14s....ie a smart alternator.

Wrangler, thanks for the tip. I just performed your tests and all is well. With the engine off, the main battery reads 12.63v across the negative and positive posts and the ESS battery reads 12.65v when isolated by pulling the negative lead.
I do have a Taser with ESS Kill activated and I tested that by pushing the dash button to turn ESS on and it does work properly. No error messages about battery charging or anything else. So it looks like I am in good shape. Appreciate the help.

I’m glad it’s all working correctly, I still have no idea why some are seeing 14.2-14.4 all the time as from what I have been told by several FCA techs that’s not normal and not the way the system was designed to charge, the charging amount is supposed to vary based on the condition of the batteries.

For me today when I first got in my Jeep the displayed EVIC voltage was 13.4 and within 20 mins of driving it dropped to 12.9 and by the time I got home it was 12.6-12.8 so I just checked the combined voltage of both real quick and I read 12.75 and I am currently running double programmers for testing
 

WWRuby_Svi

New member
Mine shows 14.2 or a little more all the time, even on 5+ hour road trips. I do have the alpine radio so i don’t know how much that affects the battery. Sometimes if the Jeep has sat for a week or so then it takes a few days of about 30min drives to and from work to charge up the ess battery before the Jeep will actually shut off when coming to a stop. I just always figured this was normal since I haven’t had problems.


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Wranglerman

New member
Is this real? Do people really wonder why a battery is running at 14 instead of 12.6? Jesus.


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Well when you see your voltage do what mine did right after purchase it makes you wonder if all is well, like I said when I first purchased my JL the idle voltage ran 12.7-13 and pretty much read the same going down the highway at 70 mph but if I braked or let my foot off the gas it ramped up to over 14.4 so I asked the service ppl what the hell was going on as I was used to seeing 14+ all the time on every vehicle I have ever owned and they advised it utilized a newer charging technology.

So I was good with that but then over a period of a few months it gradually went up to over 14 and stayed there and ESS did not work as it said battery charging all the time but when I went in for another service issue I brought it to there attention about ESS not working and the high voltage and after checking they found the main battery to be bad but I never had any trouble with it starting.

After repair all has returned to what it was like before and that’s idle sitting voltage can be 12.7-13.5 depending on how long it has sat and how often ESS has been engaged but after rolling on the highway for 20-30 mins it’s been 12.7-12.9 and ramps up during deceleration and once stopped drops back low again
 

OverlanderJL

Resident Smartass
Well when you see your voltage do what mine did right after purchase it makes you wonder if all is well, like I said when I first purchased my JL the idle voltage ran 12.7-13 and pretty much read the same going down the highway at 70 mph but if I braked or let my foot off the gas it ramped up to over 14.4 so I asked the service ppl what the hell was going on as I was used to seeing 14+ all the time on every vehicle I have ever owned and they advised it utilized a newer charging technology.

So I was good with that but then over a period of a few months it gradually went up to over 14 and stayed there and ESS did not work as it said battery charging all the time but when I went in for another service issue I brought it to there attention about ESS not working and the high voltage and after checking they found the main battery to be bad but I never had any trouble with it starting.

After repair all has returned to what it was like before and that’s idle sitting voltage can be 12.7-13.5 depending on how long it has sat and how often ESS has been engaged but after rolling on the highway for 20-30 mins it’s been 12.7-12.9 and ramps up during deceleration and once stopped drops back low again

No I wouldn’t. You JL people worry about the littlest things.


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wwood

New member
Mine shows 14.2 or a little more all the time, even on 5+ hour road trips. I do have the alpine radio so i don’t know how much that affects the battery. Sometimes if the Jeep has sat for a week or so then it takes a few days of about 30min drives to and from work to charge up the ess battery before the Jeep will actually shut off when coming to a stop. I just always figured this was normal since I haven’t had problems.

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That can't be normal. If my ESS did not work after our Jeep sat for a week and I had to drive it for a few days to charge up the ESS battery I would be pissed and make a warranty claim. There is no way a healthy battery will discharge in a week, either the battery is defective or the charging system is defective.

And having to make a warranty claim would piss me off even more, it's a super hassle to take the Jeep into the dealer for warranty work. Unless something big actually falls off they usually say " Oh, that's normal" and I have to fight with them to prove it's not normal. Then I have to leave the Jeep while they fix it.

As to the battery voltage gauge, all the new JLs should have similar behavior or a clear explanation for any material differences. There is something wacky if some JLs run at 14.2 or more all the time and some run in the 13s or the 12s. Our Jeep always ran in the mid 14s and now, suddenly as of yesterday, for no apparent reason, it runs in the low 13s? Why?

It appears to me that this new government mandated ESS crap is the culprit, it apparently requires substantial complication of the charging circuits to deal with 2 batteries and that Jeep does not have the new system perfected. Even more annoying is the fact that I can't simply remove the ESS battery and all related parts and circuitry so our Jeep runs off a normal single battery system that is dead reliable and cheap and easy to maintain like all our prior vehicles. Instead we have to worry about whether our batteries are charged properly and what it's going to cost to fix them when they break out of warranty!

And, in answer to Overlander's expected but nonetheless amusing jab, I want to know if the stuff in our fancy new Jeep that nailed me for well over $50k is working correctly. :)
 

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wwood

New member
If that’s abnormal, why does my wife’s Grand Cherokee run at 14 sometimes. It has a brand new interstate battery. It starts every time, so I don’t see what the problem is.


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WWRuby said his ESS does not work after the Jeep sits for a week because the ESS battery is discharged and he must drive the Jeep for a few days to charge the ESS battery up so ESS works. That is not normal.
Wrangler said the same type of thing, his ESS would not work and he got an error message saying battery charging, when he took it in for service Jeep replaced the defective battery. That is not normal.
Other JL owners have said their Jeep won't start at all after sitting. That is not normal.
Some JLs run continuously at 14v, while others run in the 13s or the 12s. That is inconsistent and not normal without an explanation for these extreme unexplained differences.
The fact that some folks don't worry about abnormal or inconsistent behavior does not mean all is well and that actual problems will not develop in the future.
 

notnalc68

That dude from Mississippi
WWRuby said his ESS does not work after the Jeep sits for a week because the ESS battery is discharged and he must drive the Jeep for a few days to charge the ESS battery up so ESS works. That is not normal.
Wrangler said the same type of thing, his ESS would not work and he got an error message saying battery charging, when he took it in for service Jeep replaced the defective battery. That is not normal.
Other JL owners have said their Jeep won't start at all after sitting. That is not normal.
Some JLs run continuously at 14v, while others run in the 13s or the 12s. That is inconsistent and not normal without an explanation for these extreme unexplained differences.
The fact that some folks don't worry about abnormal or inconsistent behavior does not mean all is well and that actual problems will not develop in the future.

If a battery is dead, that’s a problem. It is not abnormal to see a voltage of 14, though. Most modern vehicles need to be ran at least once a week, from battery drain while sitting. If it is going to sit longer than that, you need to disconnect the cables.


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Wranglerman

New member
You can actually disable/bypass the ESS battery, if you put a fused jumper on N1 to N2 and remove the ESS negative you are effectively taking the battery out of the circuit, I also have a Deltran Tender that I put my JL on if it’s going to be parked for 4-5 days
 

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Cozdude

Guy with a Red 2-Door
God some of you people are so hard headed. Go and hook up a battery charger to your battery and watch what it charges at. It will be close to 15v. It will be around 13 v if your trickle charging it. Your alternator put out and charges the battery with as much voltage as it needs to power ALL the safety and convenience systems in your jeep as well as help power it. Good god you worry about all the little shit.

I wish mfg’s would take the little gauge reading out of vehicles these days so people like you guys stop worrying about it. I can’t tell you how often someone comes to my job and thinks something is wrong cause the voltage meter fluctuates and I have to print the bulletin from GM to show it’s normal operation
 

wwood

New member
You can actually disable/bypass the ESS battery, if you put a fused jumper on N1 to N2 and remove the ESS negative you are effectively taking the battery out of the circuit, I also have a Deltran Tender that I put my JL on if it’s going to be parked for 4-5 days

Yes, I have been reading about that idea but I don't know if there are any unintended consequences of bypassing the ESS battery using a fused jumper.
Have you tried this out yourself?
 

Wranglerman

New member
Yes, I have been reading about that idea but I don't know if there are any unintended consequences of bypassing the ESS battery using a fused jumper.
Have you tried this out yourself?


I ran a week with the fused jumper and did not have anything bad happen and no error messages, I decided not to leave it installed as the Jeep is still under warranty and I even have a slightly extended warranty that is 4/48 so I carry the jumper in the glove box with some wing nuts and also have the ESS negative connected with a wing nut for easy removal so if the ESS battery craps out I won’t be stranded as I can easily put the jumper on and remove the ESS negative to get me going

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Wranglerman

New member
I dont see how the ess not working is a problem. I unplugged the sensor under my hood to stop it since I got tired of hitting the button every time I got in it.

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Yes you can disable ESS multiple ways like pulling the hood sensor which will give you the annoying tell tale on the dash or you can push the button everytime or you can disconnect the battery sensor so ESS thinks the battery needs charging, all of these things will not let ESS engage along with several other things but under normal operation with healthy batteries ESS should work correctly if one chooses to use it
 

wwood

New member
I ran a week with the fused jumper and did not have anything bad happen and no error messages, I decided not to leave it installed as the Jeep is still under warranty and I even have a slightly extended warranty that is 4/48 so I carry the jumper in the glove box with some wing nuts and also have the ESS negative connected with a wing nut for easy removal so if the ESS battery craps out I won’t be stranded as I can easily put the jumper on and remove the ESS negative to get me going

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Thanks, I like your idea and appreciate the info. Our Jeep is only a few months old so I agree about the warranty. I assume you made your jumper, I will look for the parts on Amazon. What gauge wire and what size fuse did you use?
 

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Wranglerman

New member
@wwood I was lucky enough to have someone make it for me and give me the low down on how the ESS and normal battery system are all tied together, he spent a considerable amount of time following cables and looking at wiring diaragrams.

I honestly don’t have any issues with the ESS system overall it’s just a poor placement of the ESS battery that bothered me, surly FCA engineers could have come up with a better place to locate that battery rather than under the main battery

The fuse is 40 amps and the wire is likely 8-10 ga
 

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