Possible Battery Issue ?

[WranglerMan]

I have read about some possible issues with the new JLU Wranglers in regard to battery charging, here is the short version, I have a brand new 2018 Wrangler JLU Sahara trim, there are not a lot of electrical gadgets on her just the basic factory stuff, any how as I have been going thru the menus on the dash I see the battery voltage runs at 12.6-12.8 while going down the road and its a pretty steady voltage but then if I let off the gas the voltage jumps up as high as 14.2 and then drops back down again so as I am going up and down in speeds the voltage jumps up and down but never drops below 12.6-12.7 when idle so is this normal.

Sorry if this has been discussed already but just trying to get a feel for new technology, was told by the service center at the dealer that it's normal but lots of times these guys just tell you a story to get you to go away.

Thanks

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[Rusty Teeth]

Cant say if its desired, but if your asking if the rest of us have that? Yes exact voltage readings. On the Fuse/Battery distribution box You can take a meter and see the actual voltage of the starter battery and the big battery sitting there. Now know as the husband and wife batteries, yes 2 of them.

 

[WranglerMan]

Well have been kinda watching the voltage on/off for the past few few days and when I get in it after it sits all night or all day at work the voltage initially runs 13.5-13.7 then after driving it awhile it slowly comes back down to the 12.7-12.9 and of course it ramps up on deceleration and once stopped and idle it holds pretty steady at the 12.7-12.9 range, I checked with the sales rep and he advised after checking with service they said it’s normal and we all know how honest service departments are anyway she’s only got 512 miles on her and two weeks old so not gonna worry to much unless of course it leaves me stranded

 

[Ron_H]

Well have been kinda watching the voltage on/off for the past few few days and when I get in it after it sits all night or all day at work the voltage initially runs 13.5-13.7 then after driving it awhile it slowly comes back down to the 12.7-12.9 and of course it ramps up on deceleration and once stopped and idle it holds pretty steady at the 12.7-12.9 range, I checked with the sales rep and he advised after checking with service they said it’s normal and we all know how honest service departments are anyway she’s only got 512 miles on her and two weeks old so not gonna worry to much unless of course it leaves me stranded

A 12 volt battery, 100% fully charged, has a specific gravity of 1.265 and a resting voltage reading of 12.7. Your alternator will have an output of about 14.4 volts. This results in your voltage reading being higher when your alternator is producing power and the battery takes time to settle back to it's fully charged resting reading of 12.6 to 12.7 volts.

A battery that is 50% will show a voltage reading of 12.06v.

 

[WranglerMan]

A 12 volt battery, 100% fully charged, as a specific gravity of 1.265 and a resting voltage reading of 12.7. Your alternator will have an output of about 14.4 volts. This results in your voltage reading being higher when your alternator is producing power and the battery takes time to settle back to it's fully charged resting reading of 12.6 to 12.7 volts.

A battery that is 50% will show a voltage reading of 12.06v.

So guessing when I get in it after it sits all day or all night and the voltage jumps up to 13-14 volts that the alternator is sending that voltage to the battery to ensure it’s got a charge then as the voltage comes up it sends less voltage to the battery, its pretty funny that the voltage jumps up on deceleration and when you accelerate it drops off but never goes below 12.7-12.9 and at idle either at a light or parked it never goes below the the 12+ volts so maybe it has some type of smart charging instead of the old days where there was a constant charge being sent to the battery, alsmost like a smart trickle charger

 

[BillArnett]

Well have been kinda watching the voltage on/off for the past few few days and when I get in it after it sits all night or all day at work the voltage initially runs 13.5-13.7 then after driving it awhile it slowly comes back down to the 12.7-12.9 and of course it ramps up on deceleration and once stopped and idle it holds pretty steady at the 12.7-12.9 range, I checked with the sales rep and he advised after checking with service they said it’s normal and we all know how honest service departments are anyway she’s only got 512 miles on her and two weeks old so not gonna worry to much unless of course it leaves me stranded

I’ve been seeing much the same thing. VERY ODD. Can someone explain what’s really happening here?

 

[WranglerMan]

I’ve been seeing much the same thing. VERY ODD. Can someone explain what’s really happening here?

From my very limited research there may be some type of ECM connected or built into the alternator and it detects when the battery needs a charge, for example after my JLU sits all night or all day and crank her up the voltage runs high like 13.5+ then after about 15-20 mins it slowly drops off and runs in the 12.7-12.9 range sitting at a stop with a/c and radio on, still have not found out why the voltage climbs up during deceleration and when fully stopped it drops down, I have been told that it’s somthing to do with battery management but don’t have a detailed explaination.

 

[smithrd65]

Just like the other forum topic it seems as people or looking for issues so hard they are making them up just for a conversation

 

[WranglerMan]

Just like the other forum topic it seems as people or looking for issues so hard they are making them up just for a conversation

Not really making subjects up, I am pretty old school and am almost 60 and not up on all the new technology, back in the day alternators put out a certain voltage all the time and voltage readings were rock solid so when I saw the what I call resting voltage while parked and idling reading 12.7-12.9 then as,I would decelerate coming to a stop it would spike as high as 14.2 then after stopping would go back to the 12.7 I just had never seen this but again this is newer technology and apparently some type of smart batter charging .

I am sure all you younger guys out there know more about this type of newer technology like ESS, dual battery systems etc.. but I am from an era that has starter solenoids mounted on the firewall and had 4 bbl carbs with one batter and 3-4 belts and you could pretty much fix anything under the hood with some simple tools.

 

[subiescott77]

I've noticed at times while decelerating, especially more so going down hill, there seems to be an engine brake effect. I think that's where the alternator grabs power to recharge the batteries. I'm usually around 13.4v while driving. 14.1-14.2 at a stop light with ESS engaged. As low as 12.9 or so while driving with only radio on.

 

[WranglerMan]

I have pretty much stopped looking at mine as it’s been fairly consistent on readings, 12.7-12.9 rolling down the road with AC and radio on and it ramps up to 13.5-14.0 slowing down and then again at the 12.5+ once stopped, it’s started everytime and everything works so just going to enjoy the ride and if it craps out I can worry then.

 

[subiescott77]

I'm just curious if everyone with electrical-battery-voltage issues have the 240 Amp alternator, 700 Amp maintenance free battery, and HD electrical group.

 

[Capricorn]

Since everyone of us is seeing the same thing, like 12.6v when your foot is on the pedal, and ramps up to between 13 - 14v, I think this is normal.
I am not a technical person when it comes to electric or automotive subjects but this is what I am guessing and please correct me if I am wrong:
When you take the foot of the pedal to slow down, is the gauge showing 13.x or 14.x as the alternator's charging rate, and when the foot is on the pedal, it is showing the battery charge?

 

[TIDALWAVE]

My Chevy Silverado has a high output 'smart' alternator. It acts in a very similar way to the above descriptions. The manual specifically mentions the voltage fluctuations.

 

[The Acme Company]

My Chevy Silverado has a high output 'smart' alternator. It acts in a very similar way to the above descriptions. The manual specifically mentions the voltage fluctuations.

It’s normal. The alternator charges when necessary. It takes advantage of certain situations such as deceleration. It’s counter-intuitive to us old fashioned gear heads but it is the new reality.

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