As my car experiences its first extended cold snap since delivery last November, I must say that driving a 4,400 lb iPhone on icy roads with no "engine braking" is kinda nerve racking. I do fine with "reduced regen" but on mornings like today, I get zero green showing on the power bar when I let off the accelerator. Is anyone else sketched out by this phenomenon?
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Cold Battery, No Regen, Not Fun
- Thread starter mrwug
- Start date
...I knew someone would pick up on this as soon as I pressed "reply". Yes, engine compression is there on ICE. I was referring to automatic engines where compression is minimal as transmissions tend to stay in high gears to save fuel. A manual car would more easily compress. Still, my main comment stays: our cars have physical brakes that are very capable of stopping the car without any regen. IT does take some getting used to, it's annoying, but there are workarounds and it's not a security concern.
Like others say, preconditioning on cold days is your friend. Here in QC, I've had to precondition my MYLR every. single. day. since picking it up in mid-December. Sometimes 2 or 3 time a day, if I have to go out several times a day. On really cold days, even preconditioning isn't enough and regen braking is still reduced when first driving the car. One thing I do love about my MY is that the inside of the vehicle doesn't frost up like my other ICE cars always did. Interior seems to heat up much better throughout the cabin. Nice to be able to see out of the rear side windows.
boulder.dude
Member
Gauss Guzzler
Safety Score = 42
Yeah I wish Tesla would at least program it to use the brakes to simulate regen when cold. Even if it was jerky it'd be better than unpredictable.
But @boulder.dude has an even better method - just do a terribly inefficient regen that creates lots of motor heat. That'd give a perfectly consistent feel and the motor heat could be used to warm the battery and cabin so there'd be little or no loss of efficiency.
But @boulder.dude has an even better method - just do a terribly inefficient regen that creates lots of motor heat. That'd give a perfectly consistent feel and the motor heat could be used to warm the battery and cabin so there'd be little or no loss of efficiency.
Regen is used to generate heat when the battery is too cold to accept a charge. In ScanMyTesla I can see my rear motor generate a few kW of energy in that situation. The front spends a few of those kW to generate heat to warm the battery itself, and the rest is seemingly used for cabin heating instead of using battery power. You just don't feel it, 6kW of regen isn't felt much.
If they are that icy. Reduced regen might be a good thing. First cold snap since Nov, really?
I could care less and barely notice reegen changes. Total muscle memory. Car not slowing down as much, my muscle memory puts my foot the brake. No drama. Don’t even think about it. Good to keep rotors polished now and then too.
Max regen on a dual motor is shown as 85kW by ScanMyTesla. That is a lot of power indeed, getting close to supercharger power. Whereas a supercharger requires 40C+ temperatures, regen is maxed out at 20C or even less. The car dynamically adjusts the max regen value when the battery is cool... The more you regen, the lower the maximum goes. It will go back up as you use energy from the battery.
sleepydoc
Well-Known Member
This is the problem - even with the heat on the maximum power used by the cars systems is a fraction of what is produced by regenerative braking. The car does use what it can, but above that if you can’t charge the cold battery there’s no place for it to go. It’s an unfortunate fact of physics and the current state of battery chemistry.
You’ve gotten used to regenerative braking and it’s a nice way to drive, but the brakes work. Gently using the brake is no different than regenerative braking when the car is warm. I’ll echo what others have said - take advantage of preconditioning your car.
No, it will not warm the battery occasionally when plugged in. Unless it’s charging. And it does not trickle charge. That would be a huge waste of energy if you are not going anywhere.
If you lose enough miles (over several days) it may kick in charging at some random time and top off. But it won’t last long nor warm your battery very much. So you can rely on it for warm battery, at all.
-25F and regen return quickly without charging? Maybe if you put the car in track mode. But no, it will NOT return quickly at those temps. The battery likes being above 60F !!
Next you’ll say you get full regen at 100% SOC.
BTW something not mentioned. If you keep your SOC lower you will get more regen sooner.
Preconditioning for the purposes of getting regen back will net you more total energy use. It cost more to precondition than you gain in regen. By a LOT. Just get in, drive it and use the brakes. If you want 5 minutes of cabin warming, Go for it. But it won’t put a dent in warming the battery.
True. Preconditioning the battery costs a lot of energy. Don't do it to save total energy unless you do a fricking long drive maybe? Even then, I don't think you ever recuperate it all. If you at least precondition the battery while the car's plugged then you'll have more range overall once you leave, that is true... if you need that range (long trips).
Precondition the battery fully if you absolutely want the regen as you like to drive it that way. That's perfectly acceptable, as long as you understand the cost. It's not necessary for the car.
I suggest starting the cabin preconditioning as you prepare to head out, a few minutes before. That way you are comfortable and some heat has been generated and starts circulating in the pack. This won't cost too much and will accelerate the availability of regen. I feel this is the best compromise.
Heading out and driving without any preconditioning at all is perfectly fine too. The car won't mind and it will protect everything, including reducing the available power to you. Nothing to worry about, but you'll freeze as you sit in the car (for about 1 minute as it heats quickly).
Precondition the battery fully if you absolutely want the regen as you like to drive it that way. That's perfectly acceptable, as long as you understand the cost. It's not necessary for the car.
I suggest starting the cabin preconditioning as you prepare to head out, a few minutes before. That way you are comfortable and some heat has been generated and starts circulating in the pack. This won't cost too much and will accelerate the availability of regen. I feel this is the best compromise.
Heading out and driving without any preconditioning at all is perfectly fine too. The car won't mind and it will protect everything, including reducing the available power to you. Nothing to worry about, but you'll freeze as you sit in the car (for about 1 minute as it heats quickly).
At least there are a few sane owners that understand how things really work.
I agree it might make sense if you want/need every inch of range at the start of a long trip. But it doesn’t mean it’s the cheapest thing to do.
sleepydoc
Well-Known Member
Agreed. The other reason to precondition is simply for comfort - it’s really nice to come out to a warm car! If you’re interested in saving as much energy as possible then just get in and drive like you said. Ultimately, driving in the wintertime takes more energy, no matter what you do.
Personally, I do as you suggest - I start to precondition 5-10 minutes before I go out to the car. Doesn’t use a ton of energy but it’s a nice compromise.
Similar threads
