Auto Start/Stop doesn't work anymore

[rcairflr]

I'm just a milkman, but my thought is this.

ASS is tied into the BMS as we know. If the system requires charging, I assume <75%, it will not allow ASS to engage. By setting a lower threshold ASS operates more frequently, increasing economy. In this case I feel they are viewing the battery to be sacrificial to economy.

The comment wasn't about ASS voltage limit, it was about the battery charging limit. Others here have said the same thing, that this battery only gets charged to 75%

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[rcairflr]

This is a Forscan photo. I changed it from the factory default of 75%. If you have Forscan go see for yourself

Thank you

 

[D Fresh]

The comment wasn't about ASS voltage limit, it was about the battery charging limit. Others here have said the same thing, that this battery only gets charged to 75%

You asked why it is set at 75%. It is set at 75% so that ASS functions more often. Make sense?

 

[rcairflr]

You asked why it is set at 75%. It is set at 75% so that ASS functions more often. Make sense?

Not to me. Why would a lower battery charge make the ASS function more?
A lower charge state would cause the battery to have a lower voltage, especially when there is a load on it.
I find it hard to believe that whether the battery is being charged or not has anything to do with ASS. The battery voltage (or available current)
would make more sense to me.

 

[D Fresh]

Not to me. Why would a lower battery charge make the ASS function more?
A lower charge state would cause the battery to have a lower voltage, especially when there is a load on it.
I find it hard to believe that whether the battery is being charged or not has anything to do with ASS. The battery voltage (or available current)
would make more sense to me.

There are certain things that will keep your truck from engaging ASS. The vehicle needing a charge from the alternator is one of them. If the alternator is not needed above 75%, ASS operates more often than say 95%.

You don't have to trust me. Read the manual, or even just look at the economy screen as the OP did. That's how it works. We're guessing at why it works that way, but I'm sure CAFE standards play in some.

 

[rcairflr]

The vehicle needing a charge from the alternator is one of them.

You don't have to trust me. Read the manual,

Here's is from the manual. Nothing about it being deactivateing while charging:


Enabling Auto-Start-Stop
The system is automatically enabled every
time you start your vehicle if the following
conditions are met:
• The Auto-Start-Stop button is not
pressed (not illuminated).
• Your vehicle exceeds an initial speed
of 3 mph (5 km/h) after you have
initially started the vehicle.
• Your vehicle is stopped.
• Your foot is on the brake pedal.
• The transmission is in drive (D).
• The driver's door is closed.
• There is adequate brake vacuum.
• The interior compartment has been
cooled or warmed to an acceptable
level.
• The front windshield defroster is off.
• The steering wheel is not turned rapidly
or is not at a sharp angle.
• The vehicle is not on a steep road
grade.
• The battery is within optimal operating
conditions (battery state of charge and
temperature in range).
• The engine coolant is at operating
temperature.
• Elevation is below approximately
12,000 ft (3,650 m).
• Ambient temperature is moderate.

 

[D Fresh]

Here's is from the manual. Nothing about it being deactivateing while charging:


Enabling Auto-Start-Stop
The system is automatically enabled every
time you start your vehicle if the following
conditions are met:
• The Auto-Start-Stop button is not
pressed (not illuminated).
• Your vehicle exceeds an initial speed
of 3 mph (5 km/h) after you have
initially started the vehicle.
• Your vehicle is stopped.
• Your foot is on the brake pedal.
• The transmission is in drive (D).
• The driver's door is closed.
• There is adequate brake vacuum.
• The interior compartment has been
cooled or warmed to an acceptable
level.
• The front windshield defroster is off.
• The steering wheel is not turned rapidly
or is not at a sharp angle.
• The vehicle is not on a steep road
grade.
• The battery is within optimal operating
conditions (battery state of charge and
temperature in range).
• The engine coolant is at operating
temperature.
• Elevation is below approximately
12,000 ft (3,650 m).
• Ambient temperature is moderate.

Might want to read that again, son.

 

[Ronbo]

If you're still under warranty and it's the battery it will be covered under the 3/36. I just had mine replaced under warranty earlier this year. The heat will degrade these fast and it's a good idea to put a battery maintainer on it.

Yes Sir. That’s true. The heat degrades batteries in Florida very quickly. I had mine go out and replaced by dealer earlier this year too, in May. Got maybe 20 months out of it.

 

[Rick - Saber]

I had them look at my truck recently because it had been some time (weeks to months) since I remember auto stop/start working as usual. Some on here with similar problems had mentioned a faulty battery cell as their cause. Went to the dealer to double check on that.

After them doing their tests the dealer says the truck is fine. I let them know how much I was driving lately. They told me that if you don't drive the truck much (as in not very far) and let it sit for 3 or 4 days in a row then the AS/S will take longer to kick in. In my case I have not driven it much the last few months and it does sit for a few days in a row. Recently most of where I needed to go was within 10 to 15 miles from me.

At least I have some piece of mind about it that the truck is alright. I do remember it coming on all the time when I first got the truck. My first vehicle with it and kinda miss the novelty of it turning on and off. Does not annoy me like it might do for some people.

This could be a good excuse to drive more often and make longer trips. Covid had put on damper on the scenic road trips. Planning a road trip soon so hoping that will help.

 

[AzScorpion]

I had them look at my truck recently because it had been some time (weeks to months) since I remember auto stop/start working as usual. Some on here with similar problems had mentioned a faulty battery cell as their cause. Went to the dealer to double check on that.

After them doing their tests the dealer says the truck is fine. I let them know how much I was driving lately. They told me that if you don't drive the truck much (as in not very far) and let it sit for 3 or 4 days in a row then the AS/S will take longer to kick in. In my case I have not driven it much the last few months and it does sit for a few days in a row. Recently most of where I needed to go was within 10 to 15 miles from me.

At least I have some piece of mind about it that the truck is alright. I do remember it coming on all the time when I first got the truck. My first vehicle with it and kinda miss the novelty of it turning on and off. Does not annoy me like it might do for some people.

This could be a good excuse to drive more often and make longer trips. Covid had put on damper on the scenic road trips. Planning a road trip soon so hoping that will help.

Mine was one that had a dead cell and they just replaced it under warranty back in April. There are times where I don't drive for several days and sometimes they're just quick trips so I bought a battery maintainer which helps keep it topped off. If you don't already have one it might be a good idea to pick one up.

 

[Rick - Saber]

@AzScorpion , I think your post might have been the one that inspired me to go get my truck checked out. I do have a battery charger and a jetski / boat battery tender that I might put on there every now and then. To make sure the battery is topped up. Remember checking it some time ago with a voltmeter and the voltage was still within tolerances.

 

[majorv]

I made my 2nd trip to the dealer last week because I am constantly getting the message on my nav screen that the system is off to save battery, plus I’m getting messages on my FordPass app. Oh, and AS/S hasn’t kicked on in a long time. After keeping it overnight they said it didn’t “fail” (whatever that means!) They charged it and nothing has changed…still getting messages. They basically told me there’s no use in bringing it back until it dies (assuming it’s still in warranty).

We put a voltmeter on it sitting in the garage today and it shows 12.4 volts. Guess I’ll give up and start using a battery maintainer. ?

 

[chasvs]

As others have reported in the past, if your battery health starts waning the system will disable ASS. Your battery "may" be on the way out.

Dang! Less than 3 years and battery dying? I'll be checking tomorrow and headed to the dealer! My A/S/S and Handle lock/unlock is acting you! Maybe both from a dying battery?

 

[AzScorpion]

Dang! Less than 3 years and battery dying? I'll be checking tomorrow and headed to the dealer! My A/S/S and Handle lock/unlock is acting you! Maybe both from a dying battery?

The heat is brutal on the batteries, mine had a dead cell in 18 months. They replaced it under warranty back in April.

 

[evoaire]

This is old info, but if it was accurate it should still be relevant.

Car batteries are considered fully charged at 12.5 Vdc and fully discharged at 12.0 Vdc. Although discharged I have seen them crank up an engine.

So when we are talking about 75%, we are talking 75% of .5 volt.
So 75% =12.375 Vdc, 95% = 12.475 Vdc, 100%=12.5 Vdc

Hope this helps.

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