Welcome Lighting May Drain 12V Battery

[Mach-Lee]

I've seen a few reports of 12V issues solved after disabling welcome lighting, and I think this now deserves its own topic for discussion. I haven't done a lot of testing with it personally since I disabled it shortly after delivery. I didn't have a good feeling about it behaved back then, and my suspicions may have been correct.

I believe the issue is the welcome lighting gets repeatedly triggered when you park in range of the key fobs or PAAK, such as at home. Since it relies on received signal strength (possibly time delay), anything that affects the received signal can trigger welcome lighting even though the fobs haven't moved. Simply walking around near the fob or the car could cause the signal to change and the car might think you are approaching based on that. Old timers will recall how walking around near a TV affected the reception, the effect on fob radio signals would be similar. Your body is conductive and acts like an antenna, which can absorb and reflect radio signals as you move around.

Folks with cameras in their garage could do some investigating to see how many times welcome lighting is activated per day, etc. PAAK vs. fob would also be interesting info. Perhaps standing between the fob and the car to block reception, then walking away might trigger something?

Or, it's possible the process of monitoring for fob signals alone could use too much battery, although that seems less likely than being caused by intermittent signal strength variations. Another one might be if there are other Ford fobs passing nearby (e.g. parking lot) and if it would repeatedly awake to interrogate those?

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[Benjamin Kegele]

I've seen a few reports of 12V issues solved after disabling welcome lighting, and I think this now deserves its own topic for discussion. I haven't done a lot of testing with it personally since I disabled it shortly after delivery. I didn't have a good feeling about it behaved back then, and my suspicions may have been correct.

I believe the issue is the welcome lighting gets repeatedly triggered when you park in range of the key fobs or PAAK, such as at home. Since it relies on received signal strength (possibly time delay), anything that affects the received signal can trigger welcome lighting even though the fobs haven't moved. Simply walking around near the fob or the car could cause the signal to change and the car might think you are approaching based on that. Old timers will recall how walking around near a TV affected the reception, the effect on fob radio signals would be similar. Your body is conductive and acts like an antenna, which can absorb and reflect radio signals as you move around.

Folks with cameras in their garage could do some investigating to see how many times welcome lighting is activated per day, etc. PAAK vs. fob would also be interesting info. Perhaps standing between the fob and the car to block reception, then walking away might trigger something?

Or, it's possible the process of monitoring for fob signals alone could use too much battery, although that seems less likely than being caused by intermittent signal strength variations. Another one might be if there are other Ford fobs passing nearby (e.g. parking lot) and if it would repeatedly awake to interrogate those?

I know that my car activates itself even having the fob 3 rooms over and I walk in the garage. It does not show welcome lights, but I hear relays clicking. I assume its from the alarm

Also in my office I see the lights going on many times. As I accidently walk "close" to the car. Maybe 30-40ft is the closest room away.

 

[Mach-Lee]

I know that my car activates itself even having the fob 3 rooms over and I walk in the garage. It does not show welcome lights, but I hear relays clicking. I assume its from the alarm

Also in my office I see the lights going on many times. As I accidently walk "close" to the car. Maybe 30-40ft is the closest room away.

The alarm only monitors inside the car with the ultrasonic sensors, or if the car is moved or rocked. It does not monitor for people outside the car. The only way it might detect a person without a fob nearby is if you parked with the windows down, and they happened to walk close by the window opening to trigger the ultrasonic sensor. Or possibly if they walked past the rear bumper and they were sensed by the handsfree liftgate. The cameras are all dead with the car off.

If you have empty pockets and walk past the car it shouldn't wake up.

 

[Benjamin Kegele]

The alarm only monitors inside the car with the ultrasonic sensors, or if the car is moved or rocked. It does not monitor for people outside the car. The only way it might detect a person without a fob nearby is if you parked with the windows down, and they happened to walk close by the window opening to trigger the ultrasonic sensor. Or possibly if they walked past the rear bumper and they were sensed by the handsfree liftgate. The cameras are all dead with the car off.

If you have empty pockets and walk past the car it shouldn't wake up.

So what is the clicking I hear so often then?

 

[Mach-Lee]

So what is the clicking I hear so often then?

I believe the clicking is the ABS HCU precharging the accumulators. Which occurs when the car is "woken up" from sleep. That shouldn't be happening all the time. My car only does that after I press the door button.

 

[Benjamin Kegele]

I believe the clicking is the ABS HCU precharging the accumulators. Which occurs when the car is "woken up" from sleep. That shouldn't be happening all the time. My car only does that after I press the door button.

Is this maybe part of the shut down procedure?

As we speak I am trying to measure the true 12 V I have the hood open and put the fob into the kitchen (3rooms away) and my car keeps doing the clicking sound I see the light under the hood flickers sometimes when clicking and sometimes goes off...

 

[mwtechy]

My 12v died in the middle of a 20+min drive so something else is going on with it. Some claim actual bad batteries, however they replaced my BECM. I think the problem was related to something changes in 2.7.2 for my issue personally.

I actually do have an IR camera in my garage and it's never recorded something when I'm not in the garage or at least when a spider is walking across it. My car usually goes into deep sleep after just a few hours so I'm not sure how that impacts the puddle lights. I think when parked it only activates when bluetooth movement is detected while in range and the cars motion sensors pick something up but I don't think it will do that when in deep sleep? I don't know but at least I haven't noticed anything on a camera yet. I however close my fordpass app "actually close it" when I'm not planning on driving.

 

[Mach-Lee]

Is this maybe part of the shut down procedure?

As we speak I am trying to measure the true 12 V I have the hood open and put the fob into the kitchen (3rooms away) and my car keeps doing the clicking sound I see the light under the hood flickers sometimes when clicking and sometimes goes off...

For your tests, put your fobs in a metal faraday box and disable Bluetooth on your phone if you use PAAK.

 

[Benjamin Kegele]

For your tests, put your fobs in a metal faraday box and disable Bluetooth on your phone if you use PAAK.

I have no metal faraday box but I am about 40ft further away with the fob than where it actually works for the buttons and I deactivated, deleted and reseted paak in june 21

 

[SnBGC]

At work, I park next to our break room straight ahead and my office just to the left. While sitting at my desk, I am maybe 15 ft from the vehicle. Those welcome lights are always activating. Get a cup of coffee....lights, go to the restroom pick up something from the printer.... lights. I bet they activate dozens and dozens of times per day.

No issues that I am aware of.

 

[DevSecOps]

How is this a 12v issue as your LVB will be maintained by the HVB if necessary? So, how exactly, based on the title, is the LVB "drained"?

If the battery is becoming drained then there's other issues not related to the welcome lights. If it's simply a notification that the HVB kicked in to charge the LVB, that's a different story and really no reason to be concerned unless there's an actual electrical problem outside of ones control and the notifications are continuous.

I have welcome lights turned on and have never had any issue or notification of the LVB having issues due to them. I never disable Bluetooth or PaaK.

Walk in front of any Tesla with sentry on and you'll get lights activating, screen activation, comms for notification and camera recording. I imagine in a busy parking spot it's activating many, many more times than our welcome lights ever will.

 

[Murse-In-Airy]

So what is the clicking I hear so often then?

There are a lot of relays always making clicking sounds. The HVB adding a little power to the LVB. The battery maintainer turning on the battery heater or cooling the battery if it’s too warm. I’ve spent a lot of time in my garage without a fob or phone. And these cars are almost always clicking.

As far as the welcome lights, I park right against the edge of my building at work. Just on the opposite side of the wall from my sleeping quarters and 15 feet from my office computer. If the welcome lights were a problem, I’d be on my 3rd battery by now.

Also, I was under the impression that the welcome lights worked for the first 3 times that you got close to the car then quit activating until you drove it. I didn’t think they woke up dozens of times.

 

[Mach-Lee]

How is this a 12v issue as your LVB will be maintained by the HVB if necessary? So, how exactly, based on the title, is the LVB "drained"?

If the battery is becoming drained then there's other issues not related to the welcome lights. If it's simply a notification that the HVB kicked in to charge the LVB, that's a different story and really no reason to be concerned unless there's an actual electrical problem outside of ones control and the notifications are continuous.

I have welcome lights turned on and have never had any issue or notification of the LVB having issues due to them. I never disable Bluetooth or PaaK.

Walk in front of any Tesla with sentry on and you'll get lights activating, screen activation, comms for notification and camera recording. I imagine in a busy parking spot it's activating many, many more times than our welcome lights ever will.

The title reflects that (in some cases) the 12V is being drained to the point of needing to recharge from HV battery. The way the car was designed, the 12V recharge event was meant to be rare/occasional only. Some people are seeing the 12V drain message daily, which becomes a durability issue for the 12V battery, along with a few other concerns.

The trigger threshold for an immediate recharge is 30% SoC, which is too low for daily cycling because it wears out the 12V battery faster. If the engineers wanted to do that often, they should have chosen a higher recharge threshold, like 50-60%. If you drain an AGM battery down to 30% and back daily, it’s probably only going to last a year, maybe two instead of a more typical 3-5 years.

BTW Tesla Sentry Mode is different than our cars because it leaves the DC/DC powered on the whole time. That’s the better way to do it but it drains the HV battery much faster ("phantom drain"). So Tesla keeps the voltage constant, vs. DC/DC switching on and off and cycling the 12V battery on Mach-E.

The problems will start when it gets cold out, and the battery is under more stress. If the battery is degraded in cold temps, 30% might not be enough to start the vehicle and get the DC/DC to charge it before it dies.

The 12V will also stop automatically recharging when it’s less than 5ºF. So if you park it around here in the winter and the welcome lights are going off all night, you may have a dead battery that requires a jump start in the morning. Same effect if you park with less than 15% SoC in the HV battery, 12V will not be recharged automatically so you will come back to a dead car.

Last, this issue of draining the battery daily could prevent you from getting OTAs installed. OTAs require the 12V battery to be above 80% or it will fail. If you have an OTA that requires an inhibit period that you schedule at night, the 12V may drain below the required 80% by your OTA time so it will never install. This could certainly be an issue with the current recall OTA deployment.

So in summary, the occasional 12V recharge notification isn’t a concern, but if it’s happening every day or two then it does need to be addressed before you are potentially left stranded with a dead 12V battery this winter. Turning off welcome lighting was a potential lead that seemed to solve issues for @Logal727 and @ProximusAl after exhausting other causes.

Also, I was under the impression that the welcome lights worked for the first 3 times that you got close to the car then quit activating until you drove it. I didn’t think they woke up dozens of times.

We are seeing some differences in behavior here. Only some people have this problem. Most don't and welcome lighting doesn't cause them major drains. I'd like to know why that is. I want to think software but ProximusAl probably has the latest versions of everything on his car?

 

[ProximusAl]

The only thing with me is my key is kept quite near the car, but as I’m in the UK and the key is always “hung up” on a key rack, the UK keys go to sleep after no movement. It could be faulty and somehow my key isn’t sleeping, but I have tested it and it does go to sleep.

All modules are indeed up to date on my car (Self FDRS)

 

[generaltso]

Also, I was under the impression that the welcome lights worked for the first 3 times that you got close to the car then quit activating until you drove it. I didn’t think they woke up dozens of times.

That‘s how mine behaves also. I haven’t counted, but the welcome lighting only activates the first few times I get near it with a key. After that, it ignores me.

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