Things you may not have discovered about your Model S?!

[HankLloydRight]

The "hill hold" is very well implemented. When releasing the brakes, it does so somewhat gradually. My BMW Z4 which had the same feature would release hill hold like an on/off switch. I know it's a subtle difference, but I like how Tesla does it as if you're releasing the brakes yourself with a light toe-touch on the brakes.

 

[mknox]

The "hill hold" is very well implemented. When releasing the brakes, it does so somewhat gradually. My BMW Z4 which had the same feature would release hill hold like an on/off switch. I know it's a subtle difference, but I like how Tesla does it as if you're releasing the brakes yourself with a light toe-touch on the brakes.

You're right, but on my car it does so with a kind of squeak or "groan" of the brakes as it gradually lets go. No biggie, but I don't get the groan when I release the brakes myself.

 

[mgdurand]

Mine is a "classic" pre-TACC car that just uses the regular old hydraulic brakes. I'm not sure how it does it, but it probably has something to do with the ABS/Traction Control hardware already there. Hill Assist was a feature added to my car quite a while after I first got it. My brake pedal does not move and is in the fully "released" position when Hill Assist is active. (i.e. I press the brake but when I lift my foot off, the pedal comes fully up but the car is held for a second or two).

Re Hill hold, I had always assumed that instead of the brake pads being squeezed, that the motor was being electronically "frozen," with the right amount of current to just remain stationary. I can do this on the accelerator with my foot and replicate the same feel as the hill hold though not as reliably since I have one of the old Z-80 processors installed.

 

[beeeerock]

Here's a little thing I discovered: When you are stopped on a hill with the hill assist engaged and take your foot off the brake, the brake lights will remain on until the hill assist releases a second or two later. Why I find this interesting is that I assumed the brake lights were activated by an accelerometer when slowing fast under re-gen and by a brake pedal switch whenever the pedal is depressed. There must be another mechanism at work here, because the lights remain on even though the pedal is not depressed and the acellerometer is not detecting any deceleration.

I imagine the brake lights are controlled by software with various inputs - brake switch, accelerometer, speed etc. There would likely be logic applied that doesn't just look at the pure acceleration numbers, but also the speed at which it occurs... is it necessary to show the lights if you drop from 100 to 95 km/h vs. 10 to 5 km/h over some arbitrary time increment? I could certainly be wrong and I haven't tested this extensively, but it appears there is more going on that I expected.

 

[HankLloydRight]

Re Hill hold, I had always assumed that instead of the brake pads being squeezed, that the motor was being electronically "frozen," with the right amount of current to just remain stationary. I can do this on the accelerator with my foot and replicate the same feel as the hill hold though not as reliably since I have one of the old Z-80 processors installed.

No, it's the brakes. It would be wasting energy to use the motor to hold a fixed position like that. Also, some people have surmised that doing that could potentially damage/heat up the motor, since the current would be going through a small set of adjacent windings for a longer duration. I don't know if that's a valid concern or not, but people who know more about A/C induction motors than I do have posted such assertions.

 

[beeeerock]

You're right, but on my car it does so with a kind of squeak or "groan" of the brakes as it gradually lets go. No biggie, but I don't get the groan when I release the brakes myself.

I've noticed this too... not sure why... perhaps the parking brake is being used? I thought at first it was the motor that would do the holding (and maybe it is).

...But now that I think about it, I'm not sure if the sound is heard when coming out of park on a hill, or just off of a traffic light on a hill. Maybe two separate things happening. I'm going to pay closer attention now!

 

[vitaliy]

If car parked and has no internet connection (underground garage), will I be able to turn on AC from the mobile app? I mean, will it find a way to connect to my car directly via Bluetooth/WiFi if I'm in range?

 

[beeeerock]

No, it's the brakes. It would be wasting energy to use the motor to hold a fixed position like that. Also, some people have surmised that doing that could potentially damage/heat up the motor, since the current would be going through a small set of adjacent windings for a longer duration. I don't know if that's a valid concern or not, but people who know more about A/C induction motors than I do have posted such assertions.

I thought I read somewhere that the hold is only for two seconds... which would limit heat buildup, energy wasting etc. Given that people could actually do this themselves (like riding the clutch on a hill), you'd think there would be a failsafe to prevent motor damage from heat? Although, in the scheme of things, the amount of heat might be relatively minor when compared with launching off of every traffic light on the street... ;-)

 

[!S4]

Probably the most inconsequential thing yet, but it surprised me this morning...

If you have the Cold Weather screen up with the rear defrost on the side mirrors will light up red on the screen indicating that the mirror heaters are on.

 

[mknox]

I've noticed this too... not sure why... perhaps the parking brake is being used?

No, it's definitely the regular brakes. My parking brake make a very distinctive "zip" sound when it engages/releases which isn't present with Hill Assist.

 

[Cyclone]

I've always said that if somebody wants to carjack me I'm going to get out of the car and give it to them without hesitation. I'll let the police take care of him and the insurance company take care of my car. That said, I've never been in that situation, so I can't really predict how I'd react, and even if so, to each his own I say. If you feel comfortable hopping the curb in that situation and avoiding the potential hassle, then by all means go for it. I wouldn't try that in my Model S, but I might in a 4Runner.

I was younger back then. Now I would do the same. Even the Model S can be replaced. That said, I still drive the same way and would be more than willing to move out the way to prevent an accident (distracted driving). That has happened with my newer 4Runner (not the same one as the story I shared before). I do that not so much to avoid the damage to my car, but to my body. I don't need whiplash.

 

[mknox]

If you have the Cold Weather screen up with the rear defrost on the side mirrors will light up red on the screen indicating that the mirror heaters are on.

Yes, I noticed that on a loaner I once had. My "classic" Model S (pre-Cold Weather availability) does heat the mirrors whenever I turn on the rear defroster, but the only indication of it is the snow/ice gradually melting off the mirror glass!

 

[Cyclone]

If car parked and has no internet connection (underground garage), will I be able to turn on AC from the mobile app? I mean, will it find a way to connect to my car directly via Bluetooth/WiFi if I'm in range?

No. Unless you phone acts as a wireless hotspot (to which your car connects to as a wifi network) and it has a connection too, since every routes through Tesla's servers. But in this case, your car is more likely to have connection b/c the car's antenna is likely much stronger than that of your phone.

 

[mknox]

No. Unless you phone acts as a wireless hotspot (to which your car connects to as a wifi network) and it has a connection too, since every routes through Tesla's servers. But in this case, your car is more likely to have connection b/c the car's antenna is likely much stronger than that of your phone.

Unless I misunderstood the original question, I think it could work. If you are parked in, say, a garage where there is no 3G/LTE coverage but you can connect to WiFi (for example, your home WiFi), then yes, you should be able to control the car. As far as I know, the car just has to have an internet connection and it doesn't care if it is via cellular or WiFi.

 

[Cyclone]

Unless I misunderstood the original question, I think it could work. If you are parked in, say, a garage where there is no 3G/LTE coverage but you can connect to WiFi (for example, your home WiFi), then yes, you should be able to control the car. As far as I know, the car just has to have an internet connection and it doesn't care if it is via cellular or WiFi.

I should have worded it better. What you said is what I meant. Both the car and the phone need an internet connection to Tesla's servers. It doesn't matter if that's through 3G/LTE direction, wifi, a hotspot on your phone, etc.

 

[vitaliy]

Ok, makes sense. Thanks @mknox, @Cyclone

 

[Kratus]

I do this all the time. I start the a/c about 10 minutes before leaving work. I pick up my daughter about 1 mile away. If it is a particularly hot day, say over 85 deg F, I exit the car and the a/c goes off and I immediately turn it back on before entering the building to get her so the car keeps cooling.

That's why I would like to be able to turn it on directly with the key fob, like with the Volt /Ampera.
It works even when there is no cellular network available.

 

[Big Daddy]

You can turn on the A/C from your smart phone. However, when exiting the car for a brief stop, it's easier to touch the display 2 or 3 times than use the app on your cell phone.

 

[yo mama]

I do this all the time. I start the a/c about 10 minutes before leaving work. I pick up my daughter about 1 mile away. If it is a particularly hot day, say over 85 deg F, I exit the car and the a/c goes off and I immediately turn it back on before entering the building to get her so the car keeps cooling.

What's creepy about this function is that my wife put the app on her phone, even though she has not driven (and/or been allowed to drive) the car yet. I obviously have the app, too. We were driving around the other day, with her in the passenger seat. She was able to change the A/C and honk the horn from her phone while I was driving. Seemed... odd. Now I'm mildly worried she's going to mess with me remotely via her app when I'm driving without her.

 

[EdA]

Thanks! My car is currently in transit from Fremont so I can't test this myself, but are you able to start the AC in the car from your phone while out of it and it's in park? If so, is there anything stopping me from just parking it normally, leave the car, then on the way into the store I could turn the AC on via phone?

Sometimes it takes a while to connect by the phone.