Model 3 - Preheat battery - Winter Range Concerns

[eprosenx]

I just noticed on Tesla's site that the Model 3 Mid Range has a 32 amp onboard charger (same as the yet-to-be-released Standard Range) vs the Long Range that has a 48 amp charger.

Based on figures posted at tesla website and looking at L2 output (say chargepoint) of 7.2kw @ 30A, i'm calculating 30mph. Is this a correct estimate

Wall Connector

https://www.chargepoint.com/files/datasheets/ds-ct4000.pdf

The charge point can deliver at 7.2kw @ 30A and tesla site says at this output, i should get 30mph. Which means if i plug the car for 2 hours, i should get 60 miles of range.

Yeah, there is a good chance your work charger is 30a (it is a common value) but it could also be 24a or some other amount.

It is likely though on 208v instead of 240v so 6.24kW instead of 7.2 (and there could be voltage drop below 208v even depending on distance from building).

It sounds doable, but I would be more comfortable with the LR.

Also not that I would prefer not to have to charge to 100% for my daily commute. I reserve that for trips.

 

[scottm]

You also may find value in having the 48a charger in the LR so you can regenerate recharge range faster from such a long commute in case you need to come home and turn around and go somewhere else quickly.

just to be clear, choice of words may confuse some... (the car's ability to regen has no relationship with the onboard charger spec)


If this is your only car and you frequent long trips that aren't serviced by SuperChargers but can find several high powered L2 offered along the way... then I'd get the biggest onboard charger you can, to maximize your gains from high powered L2's

Around here it's typical to see 68A L2's dotting the routes I take. I am happy that my S has 80A onboard charger so I can drink as much as possible from those sites and minimize my lunchtime delays.

 

[suwaneedad]

Thanks for the feeback. Assuming 40% range loss and starting at 90% charge, i have already lost 50% range. This means i am at a theoretical range of 130 miles of MR. Considering i have to drive 140 miles, this poses a problem. However, when i do the 140 mile trip,i make stops at two work locations both of which have charging locations. But, due to time crunch, i may be only able to plug the car two hours max at each locations. Which means 4 hours total charging at level 2 speed.
i also didn't know you can do an off-menu upgrade and get LR battery with no AWD. I will be calling tesla customer service and see what they can do.

Also those work chargers may not always be available when you arrive, particularly as EV adoption continues to grow.

 

[rsomrek]

There’s your problem. Turn down the heat and turn up the seat heater. You can use the energy in the battery for locomotion or to heat the air in the car— but not both. The seat heater uses a negligible amount of energy.

Thanks for the "help." I was only stating initial conditions and what was experienced. I'll be sure to remind you to turn off your air-conditioning, roll down all your windows and wear light clothes this summer when I'm enjoying a refreshing lake breeze and you're sweltering in TX heat & humidity.

 

[TexasEV]

Thanks for the "help." I was only stating initial conditions and what was experienced. I'll be sure to remind you to turn off your air-conditioning, roll down all your windows and wear light clothes this summer when I'm enjoying a refreshing lake breeze and you're sweltering in TX heat & humidity.

You can remind me, but in all seriousness many new owners aren’t aware that using the heat has a huge impact on range. Air conditioning is trivial in comparison. In ICE cars heat mostly comes from excess heat generated by the engine and does not have a “cost”, buy that’s not available in EVs so it has to be produced using the battery. Seat heaters are the much more energy efficient way of warming yourself in EVs.

 

[rsomrek]

You can remind me, but in all seriousness many new owners aren’t aware that using the heat has a huge impact on range. Air conditioning is trivial in comparison. People who are used to ICE cars don’t realize that heat mostly comes from excess heat generated by the engine and does not have a “cost”, buy that’s not available in EVs so it has to be produced using the battery. Seat heaters are the much more energy efficient way of warming yourself in EVs.

Thanks again. I appreciate your intention and I would agree that there may be a lack of understanding of the impact of resistance heating. In an ICE car the heat would have be cranked up to max and then throttled back. I thought we'd try 70 degrees for starters and actually dialed back as low as 68 - too cold on the feet. So I understand that this is the 'price' you pay in winter with an EV. I wish it weren't so but I'm okay with it. I know as winter really comes along, however, those seat heaters just aren't going to cut it when the outside temp is -10 or less.

 

[jgs]

Thanks again. I appreciate your intention and I would agree that there may be a lack of understanding of the impact of resistance heating. In an ICE car the heat would have be cranked up to max and then throttled back. I thought we'd try 70 degrees for starters and actually dialed back as low as 68 - too cold on the feet. So I understand that this is the 'price' you pay in winter with an EV. I wish it weren't so but I'm okay with it. I know as winter really comes along, however, those seat heaters just aren't going to cut it when the outside temp is -10 or less.

You're right. They also won't cut it for defogging your windshield, even at considerably warmer temps. (It really gets down to minus ten F in Illinois?!?)

I think it's already come up that prewarming the car on shore power helps a great deal when it's cold. I don't actually find my range loss is all that dramatic on road trips in the winter -- say 280 Wh/mi in nice weather vs. 340 in the winter? -- but it's far worse than that for local driving. There are long threads elsewhere about the factors that come into this (largely battery heating, and to a lesser extent drivetrain waste heat, IIRC), but that's the observed behavior from my keyhole. Oh, I generally keep my HVAC at 68F in the winter.

I think you're right on planning to keep the cabin heated to a comfortable temp in the winter. What's the point of getting a nice car only to endure torment every winter in order to drive it? Turning off cabin heat may be OK for occasional hypermiling, but for everyday commuting? Pfft.

 

[aaronM3]

You can remind me, but in all seriousness many new owners aren’t aware that using the heat has a huge impact on range. Air conditioning is trivial in comparison. In ICE cars heat mostly comes from excess heat generated by the engine and does not have a “cost”, buy that’s not available in EVs so it has to be produced using the battery. Seat heaters are the much more energy efficient way of warming yourself in EVs.

Interesting. I thought both heating and cooling had the same drain on the battery and hence the range. Curious to know why AC doesn't have the same impact on range as heating.

 

[smatthew]

Interesting. I thought both heating and cooling had the same drain on the battery and hence the range. Curious to know why AC doesn't have the same impact on range as heating.

Heating is done by a big resistor heating element. To get one watt of heat, you use one watt of power.
The air conditioner is more efficient. I'm unsure of Tesla's Coefficient of Performance (COP, a measure of how efficient an AC system is), but I'm fairly certain it's greater than 3.5. That means it takes less than one watt of power to remove 3.5 watts of heat.

TLDR: Air conditioning is at least 3.5x more efficient than heating on a Tesla Model 3.

Question: If using a compressor is so efficient for cooling, why not use it for heating?
Answer: A compressor's efficiency for heating drops as the outside temperature drops. It doesn't work below 25-30 degrees F. And it's more complex than a straight air conditioning system. So when you need it most, it produces the least. So you have to have a backup resistor heater.

Prediction: Tesla will eventually change to a heat pump arrangement, with backup resistive heat, but given that they haven't bothered yet, I don't see it happening anytime soon. Changing would provide an EV advantage in cold weather, but Tesla until the competition shows up......

 

[ivan801]

One very important thing to consider is the temperature in your garage (both at home and at work). I live in Utah, it gets pretty cold here in the winter, but my home garage is insulated and stays pretty warm (usually above 50F), so I start out with a relatively warm car (and battery). My office parking is also warm-ish, it never drops below 40F.

I have a friend with a similar commute and the same car, but his remaining range at the end of the day is MUCH lower because he has a car port at home and parks on the street at work.

 

[dumbass]

Aaron, as a Leaf owner in Chicago, I can assure you range anxiety becomes a real thing. I don't have the kind of drive you do, and the Leaf's battery is not as sophisticated as Tesla's. Still...if at all possible, get the LR. (once pulled into O'Hare with a 1% charge for a weekend trip. Back then only chargers were in very short term parking...parking was double the flight!)

You will certainly want to make a habit of preheating in the morning while plugged in. That really does help. Actually along the way too.

I appreciate the comments here about range reduction being less on the road than in town. Going to me making my first road trip soon, so thanks.

On the plus side, you won't have to pump gas when its 15F out! That really is liberating. But why replace that annoyance with fretting about state of charge?

 

[Emmexx1]

You're right. They also won't cut it for defogging your windshield, even at considerably warmer temps. (It really gets down to minus ten F in Illinois?!?)

Yup. We've also had wind chills in the past year down to -40 F. In the spirit of testing the capability of the car, I want to see that temp change. I don't want it personally for my vehicle, but it will be good to have the experience.

 

[taraquin]

After driving a Model S for 5 years now I have learned a lot from winterdriving and improving range.
- Using less heat and more seat-heating is the obvious one.
- One that is also quite obvious is preheating\precharging as they give you better regen and less internal resistance in battery. Charging to 99% actually makes it worse since regen is limited due to high state of charge. Charge to 90% or less.
- Going at high speeds, cold air is more dense so aerodynamics are reduced. High speeds at low temps reduces range more compared to low speeds at low temps percentagevise compared to high and low speeds at high temps.
- Your tires matter, A LOT! Summertires and all-season tires (master of none in my mind) becomes hard and rolling resistance increases a lot when temps drop below 10C outside. Wintertires with nordic rubbercompound like the Nokian R2\R3, Michelin Xi3 and Continental CVC 6\7 all have lower rolling resistance in high temps than the stock tires on my car in summertemp (15-20C in Norway mostly). When temp drops below 10C they keep getting better due to the soft rubber compared to summer and all season. At short trips at low speeds my Nokian R2 uses about 20% less energy than my stock Goodyear RS-A2 all-season. At long trips when tires heat up due to driving and aerodynamics etc matters more the difference is still 5-10% in favor of the Nokian R2.
- Tirepressure drops when temp drops. If you had 45psi at 20C, 35psi at 0C is normal. That alone could account for 5-10% higher consumption.

In the winter I use about 50 psi (45 is normal according to car manual), I preheat and often precharge, I use seat-heater and conservative cabin-heating and range mode (not an option on Model 3). With no preheating, too low tirepressure, high climate-setting and use of all season tires in 0-10C (below that I never use all season due to ice), my range is typically 10-20% worse (30-40% compared to summer) and 30 minutes trips.

 

[jgs]

Charging to 99% actually makes it worse since regen is limited due to high state of charge

Yes, it makes your Wh/mile worse until you deplete the charge a little so regen can operate. Of course it doesn't make your range worse, it makes it better.

 

[mswlogo]

Thanks for the feeback. Assuming 40% range loss and starting at 90% charge, i have already lost 50% range. This means i am at a theoretical range of 130 miles of MR. Considering i have to drive 140 miles, this poses a problem. However, when i do the 140 mile trip,i make stops at two work locations both of which have charging locations. But, due to time crunch, i may be only able to plug the car two hours max at each locations. Which means 4 hours total charging at level 2 speed.
i also didn't know you can do an off-menu upgrade and get LR battery with no AWD. I will be calling tesla customer service and see what they can do.

Folks need to stop doubling up on the worst case numbers. As the post you replied to said “up to 40% depending on length of drive”. If you really have a 140 mile trip it’s not gonna be a 40% hit.

You’re taking worst case numbers on a short trip (e.g. 5 miles) and applying it to a long trip.

 

[Big Earl]

Folks need to stop doubling up on the worst case numbers. As the post you replied to said “up to 40% depending on length of drive”. If you really have a 140 mile trip it’s not gonna be a 40% hit.

You’re taking worst case numbers on a short trip (e.g. 5 miles) and applying it to a long trip.

Right! Although his 140 mile drive consists of at least one stop, and it sounds like it's actually two. That could result in three cold-soak events, which will impact his consumption significantly compared to 140 miles of straight driving with no stops.

As for charging at work, definitely take advantage of this. Most workplace charging is 30 amps at 208 volts. At about 6 kW, OP be looking at about 24 miles of rated range per hour of charge. If charging for 4 hours, that's nearly 100 miles of additional rated range. I emphasized rated because that energy won't get you as far in the winter, so the actual usable range added is probably around 70 miles.

 

[taraquin]

Yes, it makes your Wh/mile worse until you deplete the charge a little so regen can operate. Of course it doesn't make your range worse, it makes it better.

Makes your consumption worse. That was my point Where I live, starting with 99 or 97% battery would give same range since I live on top of a high hill

 

[taraquin]

Heating is done by a big resistor heating element. To get one watt of heat, you use one watt of power.
The air conditioner is more efficient. I'm unsure of Tesla's Coefficient of Performance (COP, a measure of how efficient an AC system is), but I'm fairly certain it's greater than 3.5. That means it takes less than one watt of power to remove 3.5 watts of heat.

TLDR: Air conditioning is at least 3.5x more efficient than heating on a Tesla Model 3.

Question: If using a compressor is so efficient for cooling, why not use it for heating?
Answer: A compressor's efficiency for heating drops as the outside temperature drops. It doesn't work below 25-30 degrees F. And it's more complex than a straight air conditioning system. So when you need it most, it produces the least. So you have to have a backup resistor heater.

Prediction: Tesla will eventually change to a heat pump arrangement, with backup resistive heat, but given that they haven't bothered yet, I don't see it happening anytime soon. Changing would provide an EV advantage in cold weather, but Tesla until the competition shows up......

Actually taking advantage of their heat recyclyng system and using it for heating cabin would be a big improvement. The eGolf uses was heat from battery, engine etc to heat cabin. My aunt has one and the range is 20-30 km longer on their model than the one without. On a 24kW battery that makes a lot of difference. High consumption in cold weather is the biggest flaw of the Model S. With same tyres (Nokian R2) and climate off it uses slightly more energy than the Leaf 2013. When turning on climate with range mode in 0C Model S uses about 3kW for 22C, the Leaf uses 3kW first 5-10 minutes, after that it uses about 1kW.

 

[tburk32]

My scheduled delivery is 12/14 for a MR RWD. That same weekend, I have a trip planned to visit my parents which is a 200 mile round trip, temperatures in Pennsylvania are typically around 32 or slightly lower at this time of the year.

A majority of the driving is going to be highway at 70-75 mph. Do I need to worry that by using the heated seats and heater that I will not make it back home? Crazy to think that I just bought a car that I'm worried won't make that trip in the winter.

 

[TexasEV]

I wouldn’t say worry about, just use best practices— Start with 100% charge. Always preferentially use the seat heater in winter and set heat temp down to what you’re comfortable with when having seat heater on. That’s what it’s there for. Plug in at your parents house, even if’s only 120V. If you find yourself using more range than you expect, just slow down by 5 mph.