ZenRockGarden
Active Member
Mild weather certainly helps both on battery temp and use of interior climate controls.
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Really low range
- Thread starter Max trieu
- Start date
Mild weather certainly helps both on battery temp and use of interior climate controls.
This is the key point. By not preconditioning, she is forcing the car to drive, heat the battery and heat the cabin all at once. Driving an EV with a dead-cold battery is very inefficient. I always precon, even though the car sits in my garage. I'd give up the (maybe) 1% it costs me to have a much more efficient drive.
ZenRockGarden
Active Member
I have sympathy for those in cold climates and no garage, but it's a really difficult use case for an electric car. It doesn't generate heat as a byproduct of burning gas, so yeah unfreezing cabin and battery each morning is gonna clobber your efficiency.
This should be on the practical-sincere-advice list for those considering Tesla (or any other electric): "Do you have a garage with a place to plug the car in? This is by far the best way to operate your potential electric car"
Difficult use case? There are thousands of Teslas and other EVs in Quebec where freezing is the name of the game and most don't have a garage. Nordic European countries thrive on EVs and they also see multiple months of freezing. It's not a problem.
EDIT: Freezing is a problem for ICE as well. They don't start, they take 15 minutes to heat up, etc. Nothing's perfect.
EDIT: Freezing is a problem for ICE as well. They don't start, they take 15 minutes to heat up, etc. Nothing's perfect.
ZenRockGarden
Active Member
Just trying to reduce the rate of "This stupid car can only go 150 miles, not the 300 I was promised!" posts
Education is the key, it takes a while to change something everyone's been used to for all their life. Yes, driving habits, rolling resistance are more important on an EV and that strikes people at first. Less intuitive is that the battery contains energy, not miles. Running the HVAC, turning on the lights, all sorts of things consume energy from that same battery. You could completely deplete it without having driven a single mile.
300 miles of EPA range is exactly that, cover 300 miles of distance if you drive like in the EPA test. That means no HVAC, slow-ish driving in ~70F weather. I'm sure it can do it, and many people do better than EPA. If you read up on the EPA test (Education), it won't be as surprising.
300 miles of EPA range is exactly that, cover 300 miles of distance if you drive like in the EPA test. That means no HVAC, slow-ish driving in ~70F weather. I'm sure it can do it, and many people do better than EPA. If you read up on the EPA test (Education), it won't be as surprising.
Good luck with that! Seems like a new one posted almost every day.... But the manufacturers do need to do a better job of publicizing the difference between warm and cold weather range. I suspect they won't do that until forced to by some regulation, just like they aren't required to provide 'real world range' and instead are using outdated EPA tests (certainly not their fault - they have to use what they are given). Just like ICE cars are required to provide city, highway and combined fuel mileage ratings, EV's should have to display averages for warm/cold ranges.
It’s a fair criticism though. ICE cars do not halve in range in any weather.
ZenRockGarden
Active Member
The way to look at is both vehicles "burn" an extra gallon of energy in cold weather for heating.... unfortunately that's 10% of the gas tank, but 40% of the battery tank. Gas cars are saved by being really inefficient in the first place so a gallon of waste doesn't hurt as much.
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Preconditioning the battery really isn’t necessary, and it won’t improve driving efficiency aside from enabling regen. The added regen will (almost) never make up for the energy used to heat the battery.
Battery heating while on shore power can be beneficial for driver experience (regen). Battery preconditioning from shore power is most effective when it’s used to bring the pack up to temperature prior to seeing out on a road trip where you’ll be DC fast charging. That heat would need to be added by expending battery power while en route to the supercharger, thus doing it from shore power improves range on the first leg of a road trip. It should be noted that preconditioning only warms the pack to about 10°C, so it will still need to precondition for supercharging even if you warmed it up on shore power.
If you monitor your consumption from the wall, you’ll find that it is more efficient overall to not precondition longer than necessary to heat the cabin.
It’s also worth noting that 3/Y will not actively heat the battery just by getting in and driving. You must either precondition or navigate to a supercharger. Not sure about S/X since I don’t have one of those.
It's because there are two very separate concepts that work in opposite ways that people try to smoosh together in simplifying whether EVs are "good" or "bad" in cold weather.
Reliable functionality? Yes--very good. Push button and go. Never have trouble starting. This is a big plus.
Efficiency or energy use? No--noticeably very high energy usage, and generally surprising and disappointing to people new to it.
Now that the Tesla Model 3, Model Y support blended friction braking when regenerative braking is reduced or unavailable the benefit of warming the battery prior to driving are so that the battery can output more power on demand. If you drive with the blue snowflake the maximum available power is reduced; you may not notice the reduced power if you don't test the 0 to 60 time when the blue snowflake is visible.
There is currently no way to disable battery warming. If the battery is cold enough the Tesla Model Y will warm the battery some amount while preconditioning. This can also happen if preconditioning while not plugged in. Maybe in the future Tesla could provide an option to disable battery warming while preconditioning as this would save energy.
Regarding using shore power while preconditioning the power used for preconditioning comes from the battery. The AC voltage would have to be stepped up to ~360V or 400V rectified to DC and sent to the AC Compressor and to the motor stators when warming the battery. That would be quite a bit of high power wiring, redundant as well. A trace of the high voltage wiring in the Tesla Model Y would only find a single set of high voltage cables exiting the power conversion system AC to DC converters and those go to the battery.
Another consideration is that the Tesla Model Y can be plugged into 120V/20A (1.9kW) or 120/15A (1.44 kW) or one of the lower power 240V circuits such as 240V/20A (3.8kW) None of these shore power connections can deliver anything close to the power needed to run the heat pump's AC compressor or warm the battery using the motor stators. There is not enough there there. The only source of enough power to perform the heavy lifting of running the heat pump's AC compressor and when needed heating the motor stators is the high voltage battery. The AC compressor alone can draw ~8kW; the stator warming draws ~3.5kW per drive unit. The maximum power demand when preconditioning and warming the battery could exceed 15kW. The maximum Level 2 charging rate is only 11.5kW. All of the needed power for preconditioning and battery warming can only be satisfied by the high voltage battery. The shore power is there to replenish the power drawn from the battery while preconditioning.
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