Even if you did find Andy's old message I think there's a risk in relying on that information anymore. That was almost 2 years ago and who knows what Tesla has changed WRT Range Mode in dozens of firmware updates.
Mike
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Even if you did find Andy's old message I think there's a risk in relying on that information anymore. That was almost 2 years ago and who knows what Tesla has changed WRT Range Mode in dozens of firmware updates.
Mike
Only for the limited purpose of understanding if Range Mode should be off if charging in very cold weather. I think if that information came to light since that time we would have been notified about it particularly if it would damage a battery don't you?
jgs
Active Member
What do you find dumb about it? The fact you have to turn it on every time? (I agree, that's annoying.)
OR that it's buried in the menus like something someone would rarely use. OR that it doesn't turn on (like the heated seats or any of the defrosters) when you pre-warm the car remotely. OR that it's not used intelligently when turning on range mode, i.e. if the set climate control temp can't be maintained with "reduced performance" of the heater, automatically/intelligently warm other items being used.
I can think of more features too that are only severals of lines of code which would be extremely convenient for owners. Hasn't that always been the point? The futuristic car that you don't even have to start, get in and go.
jgs
Active Member
Yeah, I dunno. Most of those, I don't think I'd want. Either persisting it on (like the front seat heaters do) or making it easier to toggle on would be welcome. Beyond that, I wouldn't want it on during pre-warming since I find my wheel heats up in like 60 seconds, so why burn the power to pre-warm it? Likewise, I can see some people being quite annoyed if it started warming up without being told to (the range mode thing). Point not being that you're wrong (it's a matter of taste, so of course you're not wrong but neither am I) but rather that it's not so straightforward for them to do the right thing when people disagree on what "the right thing" is. They could toggle every single thing we've discussed but then see many instances of the "OMG it's hard to manage a software product with lots of toggles" discussion.
Just curious -- do you use your wheel heater every time you drive in the winter? Or are you in a region where it's only required now and then? For me, I use it pretty much every time from around now til spring, and so the UI moves required to turn it on have become reflexive, I don't even notice it any more.
Speaking of dumb stuff, do newer models have any way for rear passengers to control their own seat heaters? I'm guessing still not. And how about the wiper warmer? Now there's a feature I think should be exposed better in the UI and also made to function automatically (wipers on, temp below freezing? warm them!).
First of all no, none of the inconvenience needs to exist, it doesn't need a complicated interface to not do annoying things. Second, the reason for using it is exactly that it takes very very little power, versus turning on the cabin heater. For the cost of running the cabin heater to preheat for 5 minutes, you could run the steering wheel heater for TWENTY HOURS.
Every single time. Way more efficient and faster than blasting the cabin heater, plus it helps to defrost my hands from being outside.
Never seen it.
I referenced this above. If you prewarm the car, you want that thing to melt before you get to your car.
jgs
Active Member
I neglected to mention that I sometimes find the steering wheel to actually become uncomfortably hot. It would be perfectly straightforward to give it an independent toggle on the smartphone climate control screen, though, which ought to please everyone. For the same reason, I wouldn't want it rolled in as an always-on part of range mode. I mean, you could equally make the argument that range mode should automatically activate the seat heaters, but some people hate, hate, hate seat heaters ("makes me feel like I've wet my pants"). Can't fathom it myself, but there you have it.
It would be straightforward to have software driven PWM heat control like the heated seats have. You could actually match cabin set temperature based on a pre-calculated lookup tables. This is like an afternoon for a senior engineer to implement. No one at Tesla is looking at this, that is the only explanation, neglect.
But regardless, this range mode thing is just freakin dumb. We go from "Just get in and go" in the summer to pretending you're in the cockpit getting a 747 ready for flight in the winter.. Like WTF? Users have to guess that range mode on always kills the batter heater. And maybe that changes in some random software release, with no warning.
SmartElectric
Active Member
Different seats. Different heaters. Who knows how many versions of the heating element there are.
ThosEM
Space Weatherman
I'm very interested in extreme weather range and hence this discussion.
I question the basic premise that a warm battery has greater range than a cooler battery. I assumed that the reason for routing waste heat into the battery pack when in range mode is to conserve battery power by reducing the demand for resistive battery heating. If it raises the temperature of the battery above a normal operating value, it seems to me that energy is being wasted and the potential advantage is not being realized. That may account for the lack of observed range difference that is troubling some of us.
Maybe I'm missing something but I see no reason to expect a warmer battery to have a greater range. In my view the only path to greater range is reduced consumption. There isn't any way I know that the amount of chemical energy stored in the battery could be affected by its temperature. Tesla puts that blue bar on the state of charge indicator when the battery is very cold, but they don't increase the rated range when the battery is warm, so I think they are indicating that battery pack heating is going to sap a significant amount of range if the battery is cold, as indicated by the blue bar.
It is absolutely inexcusable that Tesla doesn't provide for reversing the heat pump to be a heater when that would be useful. This is an even more disappointing aspect of the Model S than the frunk hood dimple.
And why not scavenge the regenerative braking energy even when the battery is too full or too cold to accept it? Much of that energy could seemingly be put into pack and-or cabin heating when it is cold, into powering the AC when it is hot, or into an actively cooled resistor otherwise. The advantage would be that the one pedal driving characteristics of the car would not then depend on battery state of charge or temperature. When it's cold or hot, energy recycled into heating or cooling is just as valuable as energy recycled into battery charge.
Admittedly, the fraction of the time when the battery cannot accept charge is quite small, so I can see the argument for omitting extra complexity. My workaround is never to charge the battery above about 95%, preventing the regeneration limit from coming into effect. But that doesn't address the cold battery regen limit.
I question the basic premise that a warm battery has greater range than a cooler battery. I assumed that the reason for routing waste heat into the battery pack when in range mode is to conserve battery power by reducing the demand for resistive battery heating. If it raises the temperature of the battery above a normal operating value, it seems to me that energy is being wasted and the potential advantage is not being realized. That may account for the lack of observed range difference that is troubling some of us.
Maybe I'm missing something but I see no reason to expect a warmer battery to have a greater range. In my view the only path to greater range is reduced consumption. There isn't any way I know that the amount of chemical energy stored in the battery could be affected by its temperature. Tesla puts that blue bar on the state of charge indicator when the battery is very cold, but they don't increase the rated range when the battery is warm, so I think they are indicating that battery pack heating is going to sap a significant amount of range if the battery is cold, as indicated by the blue bar.
It is absolutely inexcusable that Tesla doesn't provide for reversing the heat pump to be a heater when that would be useful. This is an even more disappointing aspect of the Model S than the frunk hood dimple.
And why not scavenge the regenerative braking energy even when the battery is too full or too cold to accept it? Much of that energy could seemingly be put into pack and-or cabin heating when it is cold, into powering the AC when it is hot, or into an actively cooled resistor otherwise. The advantage would be that the one pedal driving characteristics of the car would not then depend on battery state of charge or temperature. When it's cold or hot, energy recycled into heating or cooling is just as valuable as energy recycled into battery charge.
Admittedly, the fraction of the time when the battery cannot accept charge is quite small, so I can see the argument for omitting extra complexity. My workaround is never to charge the battery above about 95%, preventing the regeneration limit from coming into effect. But that doesn't address the cold battery regen limit.
jgs
Active Member
I've wondered about those too, although it may be a case of easier in theory than in practice and as you later point out, might have small practical payoff in terms of energy usage. I'll add that this is especially true on long trips since the pack will be up to temperature relatively early in the trip. Long trips are probably when range is most likely to be important (I'm sure there are exceptions, including one all-day multi-stop holiday shopping in -20C weather mentioned upthread).
Of course active cooling itself would consume energy and so would serve to decrease range (maybe only a little but this whole thread is about small-percent changes in range). It would definitely be nice to keep the driving characteristics uniform though -- the behavior when regen is completely disabled can be outright alarming. But in the unlikely event Tesla were to actually take this on, it seems like it would be worth at least investigating doing it using the Bosch brake-by-wire system present in all AP cars (so, all cars built since 2015 or even very late 2014). That has the advantage of already being installed in the majority of the fleet and besides that, already having a system for radiating heat without any need for active cooling. It has the disadvantage that it amounts to a blended braking system, which the conventional wisdom says Tesla has been wise to avoid to date.
My understanding is that the internal resistance of the battery increases as it gets colder, which means you get less usable power out of it. (And why with ludicrous mode you can heat the battery to lower the internal resistance so you can get the most power out of it.)
As for using the "waste" battery/motor heat for the cabin heating Tesla probably figured out it was more complex than it was worth. Not to mention that when it is really cold there is no "waste" heat as the motor heat is piped into the battery to keep it warmer. (And even then sometimes they need to turn the resistive battery heater on to warm it up more.)
I suspect it is because they want it to be predictable. I think the cabin and battery heaters are 5kW/each, which means if the battery is too cold to accept a charge the most regenerative braking you could get would be 10kW which is only 16% of the full normal regenerative braking. (And that is assuming you wanted the cabin heater at full blast, which you probably wouldn't have it set for to anyhow.)
jgs
Active Member
They do allegedly use the waste battery/motor heat to warm the cabin when they don't need it elsewhere. What @ThosEM was complaining about was that they don't use the A/C compressor in "heat pump" mode when heating instead of cooling. (At least, I reckon that must be what he meant.) I can imagine various reasons they may not have done this. Air-source heat pumps are pretty much useless in really cold weather anyway, it's only during the shoulder season or in mild climates that they're any good.
Yes, but are the 'getting' the wrong thing? If range mode uses energy to make the car more efficient, then the pertinent criteria is length of travel (paying off that investment). It isn't trading performance for energy savings at all. "Range" would seem to be a better single word than "Econ" for that trade-off.
Thank you kindly.
I have seen speculation that the air conditioner Tesla uses is a heat pump and other places people have said that it's a more conventional A/C unit. A conventional A/C can't really be used for heating.
I did find this auction on Ebay for a Model S A/C unit:
2014 14 TESLA MODEL S AIR CONDITIONING COMPRESSOR AC COMP UNIT PUMP | eBay
As I understand it Tesla uses a resistive heater for their cars, which uses a fair bit of power, but has the advantage of instant heat.
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