Battery voltage driving me crazy

WranglerMan

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As the title states the battery voltage displayed is driving me crazy trying to figure it out, when I first got my JLU a few months ago the voltage displayed would run 12.7-12.9 going down the road with everything on and as I would slow down it would increase and then once stopped and idle it would drop back down to the 12.7-12.9 and I was told this was normal as its designed to charge only when needed but now I am seeing it display 13.7-13.8 all the time except when ESS kicks in at a stop if I forget to turn it off and then once it shuts down at a light with everything on it drops to 12.2-12.3 and once it starts up again it goes back up to the 13.7-13.8.

I have never had any issues starting as in a dead battery and no error messages or warnings displayed so with all my rambling what’s up with it and do I have possible issue.
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mwilk012

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That's a pretty normal sounding response from this type of electrical system. When the alternator is charging the battery it is going to read high, as there is no way to measure just the battery voltage but rather it measures the entire system. Of course, it's under warranty so you can take it to the dealer to make sure.
 
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WranglerMan

WranglerMan

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@mwilk012 I have an appt on the 9th to have the U62 recall done and plan on mentioning this along with a few other concerns, it just seems like it’s charging high all the time now, in the old days seeing 13-14 volts constantly was the norm but I was under the impression that some some of ECM only charges when necessary and would jump up and down as needed but now it’s holding steady at 13.8 but like I said no issues or error messages.
 

mwilk012

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Well I'm no electrician, let us know if they say anything about it when you go in. I'm having unrelated electrical issues with mine and it's a bear to work on.
 

WXman

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Ford calls this system the "Battery Management System" but I don't know if FCA has a name for it or not. In any case, the computer uses a strategy to engage the alternator at certain times and maintain a certain battery charge level. This depends on RPM, speed, temperature, electrical load, and other things.

It could be changes in outdoor temperature, A/C usage, or any number of things that's causing your Jeep to charge more right now than it did when you first got it. I think it's 100% normal.
 
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WranglerMan

WranglerMan

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Thanks so far for all the replies gents, I am somewhat OCD driven and the way it jumps around drive me crazy, back in the day seeing a constant 13.5+ was perfectly normal but vehicles in general were easy to diagnose as far as problems.
 

redracer

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The higher the voltage when running, the less charged your battery is.

Or, another way of saying it.... When your battery is fully charged, the system will stay at around 12.6v - 12.9v . If your battery is about dead, the system will run at around 14v.

I'd suggest that you put your battery on a charger overnight.

Also, FYI, I had my Jeep die after not driving it for a DAY. I charged the battery and it was fine for the week, but right now it's at the dealer and they are troubleshooting it.
 

sm16

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The higher the voltage when running, the less charged your battery is.

Or, another way of saying it.... When your battery is fully charged, the system will stay at around 12.6v - 12.9v . If your battery is about dead, the system will run at around 14v.

I'd suggest that you put your battery on a charger overnight.

Also, FYI, I had my Jeep die after not driving it for a DAY. I charged the battery and it was fine for the week, but right now it's at the dealer and they are troubleshooting it.
Is this right? My battery always starts the morning around 14v and as I'm driving it fluctuates between 12.8-13.8. You think I have an issue with my battery?
 
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WranglerMan

WranglerMan

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@sm16 mine to has been starting at the 13.8-14 range everyday as well and after say a 30-40 min drive it drops to like 13.7 but no issues even after setting a day as it starts right up but when I go in for my recalll I am going to have the check the battery and see if they can do a load test, I’m sure testing the battery and charging system is a pretty quick test
 

Ron_H

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Dashboard voltage gauge readings are commonly misunderstood. They alert you to the current voltage of your electrical system and can be useful in diagnosing a variety of electrical issues but their information cannot be extrapolated as a battery or alternator condition indicator without knowledge of how the electrical components and voltage works.

A fully charged battery will measure 12.6 - 12.7 volts and it should not be drawn below 12.1 volts, when measured correctly. Depending upon how and when the voltage is measured, that same battery can read over 14 volts or under 12.1 volts. If a battery is being charged or was recently received a charge level voltage, it will read higher. Transversely, if the battery is under load it will read a lower voltage and can even drop down into the sub-12 numbers and still be perfectly okay. A battery will only reveal true values if measured in a rested state, with no load and not less than 30 minutes after receiving any charge.

On older electrical systems, the system voltage displayed on the gauge would read up to 14.6 or 14.7 volts whenever the vehicle was running and everything was working correctly. With many newer vehicles, the alternator does not put our a continual charge so the reading can be considerably lower at times, especially when the battery is being drawn upon. With the JL's newer battery management system and dual batteries, analyzing the voltage reading is even more complex and convoluted.

If you want to check your batteries condition, you must fully charge the battery, let it sit, without a draw for at least 30 minutes, and use a battery load tester to measure its ability to hold a charge. I do not believe a dash voltage meter is of much value to the average driver and only adds confusion and misunderstanding.
 

sm16

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@sm16 mine to has been starting at the 13.8-14 range everyday as well and after say a 30-40 min drive it drops to like 13.7 but no issues even after setting a day as it starts right up but when I go in for my recalll I am going to have the check the battery and see if they can do a load test, I’m sure testing the battery and charging system is a pretty quick test
Thanks. Would be helpful to hear what they think.
 
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WranglerMan

WranglerMan

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@RonH thanks for all the great info and thanks for all the other info others have given as well, my JLU Sahara has not given me a lick of problems as far a starting or running and no error messages at all, there has been on occasion a dash display staying lit longer than expected but I think this is a software glitch.

As I said I am somewhat OCD and it just bugs me to see the crazy voltages but the Mrs told me not to obsess about it but I had another Jeep vehicle ( not a Wrangler ) give me electrical nightmares so I am now at high alert on what info is displayed and then I also read about all the other issues others have had so maybe I am looking for a problem that does not even exist
 
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WranglerMan

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Forgot to post here on my battery voltage concern, I told the dealer service folks that it had been running high 12’s on voltage running down the road but now it’s running high 13’s and at times right at 14 and they checked the charging system and said all looks good and no codes are being generated so I’m guessing I need not worry until it leaves me stranded :jk:
 

Rhinebeck01

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Forgot to post here on my battery voltage concern, I told the dealer service folks that it had been running high 12’s on voltage running down the road but now it’s running high 13’s and at times right at 14 and they checked the charging system and said all looks good and no codes are being generated so I’m guessing I need not worry until it leaves me stranded :jk:
Will, you really have to start to listen to your Wife's advice!
 
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