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Sunday Compass did not want to start. Acted like a low battery, starter barely turned over the engine. Voltage was 11.9 and 12.0 volts showing on the gauge. After several tries and having to pump the gas pedal it started. Voltage was then showing as 14.7 volts indicating that the battery was pulling hard charge from the alternator. Let it run for an hour and shut off. Voltage was then 12.8 volts. Went to AutoZone and had charging system checked. They said battery was good and charging system was good. All seemed well on way home and in driveway.

This morning, I went to start the Compass for my wife to go to work. First hit the start button without trying to start so I could check the battery voltage on the dash. 12.6 volts. Jeep started no problem. Voice came on saying something about "unable to complete something, no phone connected/paired. Please see settings." Voltage was then only reading 12.6 volts instead of the normal 13.8 - 14.4 volt range indicating that the alternator was not working and the car running strictly on the battery. I popped the hood and checked the voltage with a meter and it also read 12.6 volts. Turned car off and restarted while watching the volt meter on the dash. It started at 13.8 volts and fell to 12.6 volts. I tried this a couple times with repeated results and shut off the car. Couldn't let the wife try to drive to work like that. Her daily commute is 142 miles.
After I got cleaned up I drove the car to Walker Jeep Ram dealer 3.2 miles away. On the way there I kept a close eye on the voltometer in the dash. Once while going down a hill when I let off the gas the voltage started reading 14.7 and started falling before returning to 12.3 volts when I gave it the gas. I let off the gas to see if voltage returned but no. Then while turning right at the next intersection volts went back up to 13.2 volts again without giving any throttle before going to 12.3 volts. Then a few seconds later back to 13.2 volts for a split second before staying at 12.3-12.1 the remainder of the drive.
Dealership was packed and said they were booked into next week. I informed them that the Compass was our only vehicle and that my wife needed to get to work so I asked for a loaner. Dealership said they had no loaners available after first asking if I bought it there (which I had not). Shuttle van took me home.
I will update later as the dealership just called and said it was ready and was sending the shuttle to pick me up.馃榾
 

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Went to pickup the Compass from the dealership. They said they couldn't find anything wrong with it but did do an update on the BCM. I got in the car. Checked voltage before and after starting It. Voltage hits 13.7 volts for a breif second after starting then drops to battery voltage of 12.6 volts. Went back into dealership informed service department that it was still not fixed and wanted to show them. Then had me pull it around and back inside where I then tried to show them. They claimed nothing wrong and that the car is designed to do that, "These new cars aren't like the old ones." They couldn't have spoken a more true statement. I then asked them" Does the cars no longer have voltage regulators or the computer control the voltage? They said yes, but.....and couldn't finish the answer. They then asked if I wanted to leave it overnight. I said, "No", because thinking if they were that inept I would rather try taking it to a different dealership.

Drove it home. Several times after hitting the brakes the alternator/voltage regulator would kick in an out the proper voltage until I hit the gas pedal.

Anyone have any ideas what's up? Car only has 33,000 miles on the odometer. 2019 Jeep Compass 4x4 Sport model 6 speed manual.
 

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It sounds like something is wrong with whatever type of regulator this car uses to control the alternator, OR the alternator itself is bad, but I don't know why or how the alternator could work sometimes and not others which is why it feels more like a regulator.

Older cars the regulator was often a part of the alternator itself and it decided on its own when the system needed more current to put charge into the battery or power the car's electronics. With these ones I don't know, maybe the PCM uses sensors and a shunt to more precisely control the alternator's output to increase economy. The more amperage demanded from the alternator the harder it turns, since it is converting mechanical energy from the belt drive into electrical energy. It can take upwards of 3-6 HP to spin an alternator at full load so any time full load isn't required the regulator should ease off (I think), but I've never seen my voltmeter on my dash read less than 14.3-14.7 volts while driving.

The alternator should always be putting out some current, as far as I know. The running voltage should always be 14.3-14.7 the only thing varying would be how many amps is being drawn depending on load and battery SOC (state of charge).

So thats why it seems like its either a regulator of some sort or one of the voltage/current sensors could be providing bad data confusing the regulator too I supposed. Probably start by checking all wires from the battery and alternator area, I've found chipmunk chew marks under my hood on occasion.

If you have AlfaOBD it should have a bunch of electrical info it can plot and log during a test drive.
 

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x2 what arudlang mentioned. Last year we had ESS issues so I kept a close eye on the DC output. One trick I used is before starting the car, Key in hand, I press the start/stop without my foot on the brake. The display comes up and I toggle to the DC voltage screen and then start the car and watch what happens. Oddly, just now, it read only 12.0v, but when I pressed the brake peddle it dropped to 11.8v ... hummm ... started the car, the voltage did not drop and then slowly moved up to 14.4 charging voltage. Last year with a bad/week battery it would drop down to 10v. I'll have to double check this with my meter next time, seems odd that voltage did not drop on start up ...
 

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seems odd that voltage did not drop on start up ...
I don't think mine drops either. Its probably either

1) The update is so slow on that gauge that its already started before it updates, or
2) Perhaps more likely, its showing the voltage of the small battery only during startup and not the larger cranking battery.

I skimmed over the annoying extra complexity of having two batteries in my earlier post but these do have two batteries. There is a solenoid that couples and decouples the two batteries in parallel based on computer command, I don't really understand when it connects them and when they are separated, but I am pretty sure the solenoid is off/batteries separated during engine cranking. Probably why the gauge on the dash doesn't drop.

So if you do test with your multimeter, I would expect the big battery to drop during cranking and the small one to stay level. If you have a continuity tester mode you can also test when that solenoid is on/off, its right near the two batteries can't miss it.
 

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I never would have thought to even look at the voltage. Considering this post I watched mine today. It was 14 (I'm not sure of the decimal) right after starting this morning. I drove it 5 miles into town and let it set for a couple hours while I did some work. When I restarted it was showing 13ish. It's never given me a problem, even in severe cold (-35F). Today was more typical winter, +8F. Hardly anything to stress it other than sitting overnight. The alternator probably didn't have to work very hard.

Most of the cars I've had that even had a gauge didn't give you quantity. As long as it stayed slightly to the charge side I was happy and so was the vehicle. Ours is a 12V system -- that would be the center point of a conventional gauge -- so anything over that means it's charging. A lot or a little doesn't matter to me as long as it starts in the morning.
 

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Discussion Starter #7 (Edited)
Most of the cars I've had that even had a gauge didn't give you quantity. As long as it stayed slightly to the charge side I was happy and so was the vehicle. Ours is a 12V system -- that would be the center point of a conventional gauge -- so anything over that means it's charging. A lot or a little doesn't matter to me as long as it starts in the morning.
Those cars must have had an amameter not voltameters. In years past, many American auto manufacturers installed amameters instead of voltameters. But starting in the late '70s (?) they started switching to installing voltameters. Occasionally, a vehicle would/will have both which is the best setup because they show different things. Anymore we are lucky to have either as the manufacturers know most Americans (I can't testify regarding other country's citizens) don't even have a clue to look at either type of guage much less know what the data means.

For those interested
Amameters are wired in series to the system and indicate whether the system is consuming more amps than produced 馃槨(left of the zero centerline), producing more amps than consumed 馃檪(right of zero centerline), or equal amounts of consumed and produced amps 馃檮(zero centerline). OEM amameters normally didn't show numbers.

Voltameters are wired in parallel to the system and indicate how many volts the system is generating. If the vehicle is not running, it will indicate the total combined voltage of the battery plus any residual voltage from capacitance that may be in the system less any resistance of the system. If the vehicle is running and the alternator and voltage regulator system is performing correctly, it will indicate the voltage output of those two components. Most voltameters show numbers.
 

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Anymore we are lucky to have either as the manufacturers know most Americans (I can't testify regarding other country's citizens) don't even have a clue to look at either type of guage much less know what the data means.
. . .
Most voltameters show numbers.
So where are the numbers on my oil temperature gauge? If ever there was a useless invention! :D

Sometimes it's difficult to find a practical use for a gauge. Maybe they should put detailed gradients on the oil temperature gauge and measure it in some obscure scale (like Rankine) that would mean nothing to the average driver.
 

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So where are the numbers on my oil temperature gauge? If ever there was a useless invention! :D

Sometimes it's difficult to find a practical use for a gauge. Maybe they should put detailed gradients on the oil temperature gauge and measure it in some obscure scale (like Rankine) that would mean nothing to the average driver.
I wish they would let us select which and what type of guages are displayed on the dash.
I somewhat agree about the oil temp gauge. Transmission temp would be more useful but why not have both.

I had a car years ago that overheated and warped the intake and head. Coolant sensor was located in the highest part of cooling system so when the coolant started leaking out it read the air temperature inside the cooling system. The temperature indicated lagged behind the engine (oil) temperature.
 
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I don't think mine drops either. Its probably either
1) The update is so slow on that gauge that its already started before it updates, or
2) Perhaps more likely, its showing the voltage of the small battery only during startup and not the larger cranking battery.
So if you do test with your multimeter, I would expect the big battery to drop during cranking and the small one to stay level.
yep, looks like a lag with good batteries. I read off the main battery and it dropped down ~10.6v. Last year with a week/dead battery it would drop, that may be an easy/helpful trouble shooting idea for others to use.

H20DOG, any progress on your issue ? Have you found a new dealership to help?
 

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...I somewhat agree about the oil temp gauge. Transmission temp would be more useful but why not have both...
They do have both, but you can only display one at a time. The transmission temperature displays an actual number, but the oil temperature only has an indicator.
 

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The oil temperature only has an indicator.
That's like the TV weatherman saying, "It will be warm a couple days this week and cool on some others. Probably a fair amount of snow sometime before the weekend." I think George Carlin did a spoof on this, "The weather for tonight is dark followed by increasing light toward morning." That's about how useful a temperature gauge is without numbers. :rolleyes:
 

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Sunday Compass did not want to start. Acted like a low battery, starter barely turned over the engine. Voltage was 11.9 and 12.0 volts showing on the gauge. After several tries and having to pump the gas pedal it started. Voltage was then showing as 14.7 volts indicating that the battery was pulling hard charge from the alternator. Let it run for an hour and shut off. Voltage was then 12.8 volts. Went to AutoZone and had charging system checked. They said battery was good and charging system was good. All seemed well on way home and in driveway.

This morning, I went to start the Compass for my wife to go to work. First hit the start button without trying to start so I could check the battery voltage on the dash. 12.6 volts. Jeep started no problem. Voice came on saying something about "unable to complete something, no phone connected/paired. Please see settings." Voltage was then only reading 12.6 volts instead of the normal 13.8 - 14.4 volt range indicating that the alternator was not working and the car running strictly on the battery. I popped the hood and checked the voltage with a meter and it also read 12.6 volts. Turned car off and restarted while watching the volt meter on the dash. It started at 13.8 volts and fell to 12.6 volts. I tried this a couple times with repeated results and shut off the car. Couldn't let the wife try to drive to work like that. Her daily commute is 142 miles.
After I got cleaned up I drove the car to Walker Jeep Ram dealer 3.2 miles away. On the way there I kept a close eye on the voltometer in the dash. Once while going down a hill when I let off the gas the voltage started reading 14.7 and started falling before returning to 12.3 volts when I gave it the gas. I let off the gas to see if voltage returned but no. Then while turning right at the next intersection volts went back up to 13.2 volts again without giving any throttle before going to 12.3 volts. Then a few seconds later back to 13.2 volts for a split second before staying at 12.3-12.1 the remainder of the drive.
Dealership was packed and said they were booked into next week. I informed them that the Compass was our only vehicle and that my wife needed to get to work so I asked for a loaner. Dealership said they had no loaners available after first asking if I bought it there (which I had not). Shuttle van took me home.
I will update later as the dealership just called and said it was ready and was sending the shuttle to pick me up.馃榾
 

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All ! ! Those Jeep compass's have two batteries! There is an auxiliary battery in the cabin causing all of those issues.. $177 from Chrysler
 

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All ! ! Those Jeep compass's have two batteries! There is an auxiliary battery in the cabin causing all of those issues.. $177 from Chrysler
Only Compasses equipped with the Engine Start/Stop (ESS) system have an auxiliary battery, and it is located in the engine compartment directly in front of the main battery, not in the cabin.
 

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our 2019 jeep compass latitude with 51,000 on it doing the same thing after dealership replaced altenator battery. problem still not fixed. so frustrated! let me know if u get it fixed please and thank you.
 
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