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Discussion Starter · #1 ·
Waiting in drive-thru line, engine idling, info display switched to battery voltage on its own and indicated 12.6v. Car continued running normally. Got home, visually inspected under hood, negative battery terminal extremely loose. Tightened fastener, restarted,but voltage still 12.6.
Went to dealer the next day (Friday). They couldn’t service till next week, no loaner or rental available. Service writer connected to OBD port, found one code related to radio to display link but nothing pertaining to vehicle electric system.
Short trip on Sunday. Voltage showed above 13, engine fully warmed up.
Longer trip on Monday. Voltage 12.6, regardless of engine rpm. When decelerating, voltage rises to 13.7, 13.9, 14.0 as engine rpm drops through 1500. At idle, voltage is back down to 12.5, then 12.6. With lights and wiper on, voltage reads 12.4, which tells me I am on battery.
If I begin to accelerate before coming to a stop, the voltage drops again. Running the engine at 1200-1500 rpm in neutral does not bring the voltage back up either. Checked with multimeter, it agrees with the readings I get on the instrument panel.
The service writer at the dealership told me that the charging system on the new jeeps has AI (artificial intelligence) and nothing is wrong since there are no pertinent codes.
Battery failed about 2 weeks ago, dealer replaced under warranty. Battery was completely dead, could not jump start. This was the reason for the loose negative terminal - the tech didn’t check his work.
I’ve worked on cars since the 1960s, so experience tells me that the charging system isn’t right.
The car is a 2021 Cherokee Latitude, 10k miles, 4cyl engine. Operation normal otherwise.
Anyone else experiencing similar?
 

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Discussion Starter · #2 ·
Waiting in drive-thru line, engine idling, info display switched to battery voltage on its own and indicated 12.6v. Car continued running normally. Got home, visually inspected under hood, negative battery terminal extremely loose. Tightened fastener, restarted,but voltage still 12.6.
Went to dealer the next day (Friday). They couldn’t service till next week, no loaner or rental available. Service writer connected to OBD port, found one code related to radio to display link but nothing pertaining to vehicle electric system.
Short trip on Sunday. Voltage showed above 13, engine fully warmed up.
Longer trip on Monday. Voltage 12.6, regardless of engine rpm. When decelerating, voltage rises to 13.7, 13.9, 14.0 as engine rpm drops through 1500. At idle, voltage is back down to 12.5, then 12.6. With lights and wiper on, voltage reads 12.4, which tells me I am on battery.
If I begin to accelerate before coming to a stop, the voltage drops again. Running the engine at 1200-1500 rpm in neutral does not bring the voltage back up either. Checked with multimeter, it agrees with the readings I get on the instrument panel.
The service writer at the dealership told me that the charging system on the new jeeps has AI (artificial intelligence) and nothing is wrong since there are no pertinent codes.
Battery failed about 2 weeks ago, dealer replaced under warranty. Battery was completely dead, could not jump start. This was the reason for the loose negative terminal - the tech didn’t check his work.
I’ve worked on cars since the 1960s, so experience tells me that the charging system isn’t right.
The car is a 2021 Cherokee Latitude, 10k miles, 4cyl engine. Operation normal otherwise.
Anyone else experiencing similar?
Update - took car to a local dealer, after checkout, they changed the battery sensor in the negative lead of the battery, said all is normal. Still have questions, however - they said 12.4 to 12.6 is the normal system voltage for this vehicle with the engine running. I had my brother check his 2018 Grand Cherokee, voltages were more in line with what I expect - 12.6 with engine off, 14.2 with engine warmed and above idle, both on the in-dash gage and with an external DVM.
If someone could check on their vehicle, I'd sure like to see the results, especially on a 2021. Thanks.
 

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My 2020 Cherokee latitude runs 12.4 to 12.6 running and charges during deceleration to save fuel. I took mine to the dealer for it and if you Google star online publication case number S2008000031 you can read about Jeeps with Smart charge mode. I made some YouTube videos of it also. I can be driving and it will be at 12.6 volts and if I let of the gas it jumps to 15.4-14.6. If they battery is low it will charge at idle but not very often
 

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Discussion Starter · #4 ·
My 2020 Cherokee latitude runs 12.4 to 12.6 running and charges during deceleration to save fuel. I took mine to the dealer for it and if you Google star online publication case number S2008000031 you can read about Jeeps with Smart charge mode. I made some YouTube videos of it also. I can be driving and it will be at 12.6 volts and if I let of the gas it jumps to 15.4-14.6. If they battery is low it will charge at idle but not very often
Thanks. Guess I need to update my old school mechanic knowledge. I’ve heard all the manufacturers are getting very creative trying to squeeze the last .1 mpg out of their fleet.
Can’t stand the engine kill at every start, so that’s the first thing that gets shut off after I start the car. Probably a double win for them, though. They get to sell more batteries and starters plus claim the ‘improved’ gas mileage.
 

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Discussion Starter · #5 ·
Thanks. Guess I need to update my old school mechanic knowledge. I’ve heard all the manufacturers are getting very creative trying to squeeze the last .1 mpg out of their fleet.
Can’t stand the engine kill at every start, so that’s the first thing that gets shut off after I start the car. Probably a double win for them, though. They get to sell more batteries and starters plus claim the ‘improved’ gas mileage.
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Discussion Starter · #6 ·
Many new vehicles are using an advanced lead-acid battery type, the Absorbent Glass Material (AGM) battery instead of the traditional lead acid cells that have a liquid electrolyte. Some may have had a gelled lead acid battery, but according to the information I found, these were not as rugged as the older technology.

From a NHTSA bulletin I found through one of the Jeep forums, that since as early as 2019, some Chrysler, Jeep, and Dodge models have been programmed with an “intelligent battery charging algorithm” to prolong battery life and improve gas mileage. It is tied in to the start-stop operation where the engine shuts off at stops, then restarts when the driver takes their foot off the brake. Supposed to improve gas mileage. It may in heavy traffic, as well as sell a lot of starter motors. Fortunately, there is a button to turn that off.

Here is a link to the NHTSA pdf: https://static.nhtsa.gov/odi/tsbs/2020/MC-10175657-9999.pdf
 

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Glad you are on here Bill. I haven't had one of these to tinker with. There is also another feature you may want to explore. In the quest to get that last tenth of a mile to a gallon, there is a code in the current that tells the device if it can have the current or go to the next device. It causes the famous flickering headlights on the new Jeeps if they use LEDs
 

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Discussion Starter · #8 ·
Glad you are on here Bill. I haven't had one of these to tinker with. There is also another feature you may want to explore. In the quest to get that last tenth of a mile to a gallon, there is a code in the current that tells the device if it can have the current or go to the next device. It causes the famous flickering headlights on the new Jeeps if they use LEDs
Thanks for the tip. We have had our Cherokee Latitude since November, this is the first snag I’ve run into. We do have the LED headlights. I formed an instant dislike for the start-stop ‘feature’ - that gets turned off immediately after I start the engine. Other than that, we love our Cherokee.
About 3 1/2 weeks ago, the battery failed the day after we got back from a trip. Finally got it jump-started, but engine would die as soon as we disconnected the jump starter. Towed (flatbed) to the dealership and they replaced the battery. All seemed good, until I looked at the system voltage. Been an educational few days, to say the least.
 

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My 2014 BMW has the start/stop feature. It can be turned off. it also has 3 driving modes, sport, normal and economy. Normal mode shows an MPG graph and if you are coasting, will max out at 50 then has a pic of a battery and says "charge". Not having consulted the manual, I am betting this is what you guys were referring to about the volts only going up on coast or deceleration. When in econ mode, the graph changes to "charge" and "power" with the "Sweet Spot" in the middle. It also puts the tranny in neutral, and the rpms drop to idle speed. As an added bonus, it tracks the additional miles you gain by running in economy mode. pretty neat. In the FWIW column, it's a 328D xdrive. AWD dual turbo 2.0 diesel. And she will scoot!! :)
 
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