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Discussion Starter · #1 ·
Hello guys, The battery on my 2020 Latitude was just replaced by the 3/36 warranty. I have noticed when driving the voltage sits at 12.8 volts mostly and sometimes goes to 12.6. While I am driving it will go up to 13.7- 14.0 for a few seconds and then goes back to 12.6 to 12.8 . The ESS says ready unless I turn it off.

I have always thought 14.0 was the charging voltage on a vehicle but mine does go there much and I wonder if FCA has it set to just charge it as needed to stop parasitic drain from the alternator and improve efficiency. I picked up my kids at school and getting them in the car loop the ESS activated several times and the battery was fine. I am planning a trip soon and with the dead battery on 2020 I just want to make the battery was the issue and not something else. Thanks in advance
 

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Hello guys, The battery on my 2020 Latitude was just replaced by the 3/36 warranty. I have noticed when driving the voltage sits at 12.8 volts mostly and sometimes goes to 12.6. While I am driving it will go up to 13.7- 14.0 for a few seconds and then goes back to 12.6 to 12.8 . The ESS says ready unless I turn it off.

I have always thought 14.0 was the charging voltage on a vehicle but mine does go there much and I wonder if FCA has it set to just charge it as needed to stop parasitic drain from the alternator and improve efficiency. I picked up my kids at school and getting them in the car loop the ESS activated several times and the battery was fine. I am planning a trip soon and with the dead battery on 2020 I just want to make the battery was the issue and not something else. Thanks in advance
Ya, I'm going to say that is not normal. Looks like they need to check the alternator. I would double check the battery connections too. Loose connection could cause that also...😎
 

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Ya, I'm going to say that is not normal. Looks like they need to check the alternator. I would double check the battery connections too. Loose connection could cause that also...😎
Definitely not normal. Unless... you read it while idling with all heaters turned on, then your alternator can't output enough to compensate for the high load. If running voltage stays below 13V (even 13.6V) while RPMs are above 1000-1200, then Houston... we have a problem...

Edit to add : drove a [new] Savana van last summer (rental) and it kinda did what the OP is describing which caught me off guard : running voltage slowly dropping while driving, down to mid 12s, then shot back up to 14V for a while, then back down. Maybe there's a new style of charging algorithm I haven't heard of...
 

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Not normal at all, you should never see a voltage below 13.47v while the vehicle is running.

Your IBS intelligent battery sensor is likely faulty
 

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It's not an issue with pulling too much power at idle. The most I could pull amp wise was a little over 90 amps. With a 160 or 180 amp alternator even at idle, it'll keep up.
 
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It could be a problem with the charging system, either the alternator or the PCM. From the service manual:

The amount of DC current produced by the generator is controlled by the EVR (field control) circuitry contained within the PCM. This circuitry is connected in series with the second rotor field terminal and ground.

If not enough current is supplied the voltage drops.

Also, low idle RPMs and high load (heaters on, headlights on, and... you get it) might be exceeding what the alternator can provide at idle. Does the voltage come up with RPMs?

Old school alternators are very sensitive to idle speed. My JK for example has a programmer to automatically kick the idle speed from 700 RPM to 1800 RPM when it detects a heavy load - like winching. Similar loads like when jumping another car might require increase in engine RPMs to provide enough current from the charging system. While the KL service manual doesn't indicate to increase idle speed while jump-starting another car, the internet is full of advice to increase the idle RPMs when jumping another car to make sure the alternator is putting out enough juice to get the job done. Perhaps the KL has a bit more down-low power available?
 
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I took it to the Jeep dealer and they said it will only charge for about 5 seconds and quit, engine RPMs or electrical does not matter. I had to leave it so I am back in my 22 year old F250. I appreciate the feed back.
Have them check the IBS and the alternator. The reason the battery is charged, cuz it's brand new, and won't take much to keep it charged up, but fluctuation in voltage is still not good...😎
 

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Discussion Starter · #14 ·
I don’t think they will either. My truck has the 7.3 power stroke and while it has mild electronics on it the only time it ever broke down on me is because the sensor on the fuel pedal went out and it would only idle.

I did replace the transmission at 175k because it was shifting funny. I had it a after market HD one built and at 525k it still runs good. I will miss it when it falls apart.
 

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It could be a problem with the charging system, either the alternator or the PCM. From the service manual:

The amount of DC current produced by the generator is controlled by the EVR (field control) circuitry contained within the PCM. This circuitry is connected in series with the second rotor field terminal and ground.

If not enough current is supplied the voltage drops.

Also, low idle RPMs and high load (heaters on, headlights on, and... you get it) might be exceeding what the alternator can provide at idle. Does the voltage come up with RPMs?

Old school alternators are very sensitive to idle speed. My JK for example has a programmer to automatically kick the idle speed from 700 RPM to 1800 RPM when it detects a heavy load - like winching. Similar loads like when jumping another car might require increase in engine RPMs to provide enough current from the charging system. While the KL service manual doesn't indicate to increase idle speed while jump-starting another car, the internet is full of advice to increase the idle RPMs when jumping another car to make sure the alternator is putting out enough juice to get the job done. Perhaps the KL has a bit more down-low power available?

The alternators in the KL are 100% capable of keeping up with any amount of load you can put on them, even at idle. Myself and @MikeR. have confirmed this.

I have pulled 132amps while idling and my duty cycle on the alternator wasn't anything close to 100%.

There is no need to increase rpm the max ouput does not change by revving it up, again I've tested this.



On my grand Cherokee should there be a large electrical load at idle, the PCM will command a 1000rpm idle speed to ensure the alternator output is sufficient
 

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Without actually monitoring the IBS you have no idea if the vehicle is actually charging the battery, voltage is not a sole indicator of a battery charging
 
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