Who has lost regen with winter tires?

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CCIE

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That's why it doesn't pay to "pre heat battery". You're better off saving money and charging when the battery is already warmest when you get home.
Letting a warmed up battery cool off overnight, without taking advantage of it to charge it right then, is wasted energy.

I don't think it warms the battery very much to get it warm enough to accept home charging rates. The regen watts are much higher and need a much warmer battery for full regen.
The car doesn’t have a battery heater and doesn’t seem to really use the motor heating function. So, I don’t think it’s costing me any more charge from 4-7am. At least I get some regen in the morning because charging does heat the battery a little.
 

CCIE

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I'm steadfast in believing that the RWD regen "issue" is also temperature dependent because of the changes in the tires rubber with changing temperature.
For me the tire tread in the Xi3 would firm up a bit at very low termperatures and improve regen a bit. But, 2018.50 has fixed the issue for me at 50F and 22F. So, temperature isn’t impacting my tire-related regen anymore.
 

mswlogo

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The car doesn’t have a battery heater and doesn’t seem to really use the motor heating function. So, I don’t think it’s costing me any more charge from 4-7am. At least I get some regen in the morning because charging does heat the battery a little.
It most certainly does use motor heating for charging. Mine clearly does. It’s not gonna be huge, but it will cost more kWh to charge a cold battery at 4 AM (unless you have off peak metering) than it will save you with 1-2 less dots on regen. It will heat the battery enough to charge at your max charge rate. It won’t heat it up enough to significantly help regen, because that’s much higher current for battery to accept.
 

CCIE

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It most certainly does use motor heating for charging. Mine clearly does. It’s not gonna be huge, but it will cost more kWh to charge a cold battery at 4 AM (unless you have off peak metering) than it will save you with 1-2 less dots on regen. It will heat the battery enough to charge at your max charge rate. It won’t heat it up enough to significantly help regen, because that’s much higher current for battery to accept.
I've yet to see any proof of motor-heating the battery during charging. I have experienced terrible cold-weather supercharging rates which indicate to me that Tesla is not heating the battery during charging.

I get much more than 1-2 dots improvement by charging at 4am. There is at least a 50% improvement in cold-weather regen reduction.
 

JWardell

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I've yet to see any proof of motor-heating the battery during charging. I have experienced terrible cold-weather supercharging rates which indicate to me that Tesla is not heating the battery during charging.

I get much more than 1-2 dots improvement by charging at 4am. There is at least a 50% improvement in cold-weather regen reduction.
It's easy to see proof if you have Teslafi or can watch your charge rate. A very cold pack will show a zero charge rate while still drawing power from your wall. As it warms charge rate will increase.
Don't write off the regen improvement either, charging can bring zero regen up to a good 50kW or more.
I now regularly start charging a half hour before leaving in the morning not to top it off but to bring up the temperature so I don't have to suffer the zero regen blues anymore.


Here's a recent morning top-off example. Temps start at 17F and I bump the charge level up to 79 to kick off charging. For the first 6 minutes NO charge energy is added even though 3kW are being drawn from the charger. Then as it starts to get warm enough, charge rate and charge energy added slowly increase. Full speed charging would be 19Mi/h but it only has a chance to get up to 8.4 when I turn on HVAC to start warming the interior. This takes all the energy away from charging so the charge rate drops to zero again as you see the interior temps start rising. I then get to drive a nice warm car with some regen!

Screen Shot 2019-01-10 at 9.39.08 PM.png
 

CCIE

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It's easy to see proof if you have Teslafi or can watch your charge rate. A very cold pack will show a zero charge rate while still drawing power from your wall. As it warms charge rate will increase.
Don't write off the regen improvement either, charging can bring zero regen up to a good 50kW or more.
I now regularly start charging a half hour before leaving in the morning not to top it off but to bring up the temperature so I don't have to suffer the zero regen blues anymore.


Here's a recent morning top-off example. Temps start at 17F and I bump the charge level up to 79 to kick off charging. For the first 6 minutes NO charge energy is added even though 3kW are being drawn from the charger. Then as it starts to get warm enough, charge rate and charge energy added slowly increase. Full speed charging would be 19Mi/h but it only has a chance to get up to 8.4 when I turn on HVAC to start warming the interior. This takes all the energy away from charging so the charge rate drops to zero again as you see the interior temps start rising. I then get to drive a nice warm car with some regen!
Cool, love seeing the data! Do you know what the temperature cutoff is to require heating the battery before commencing charging?

Even knowing that the car is heating the battery for charging, I would still schedule to charge at 4am. That way it is still charging, or has just completed charging, when I elave the house in the morning. I like having regen and a warm/happy battery in the morning!
 

JWardell

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Cool, love seeing the data! Do you know what the temperature cutoff is to require heating the battery before commencing charging?

Even knowing that the car is heating the battery for charging, I would still schedule to charge at 4am. That way it is still charging, or has just completed charging, when I elave the house in the morning. I like having regen and a warm/happy battery in the morning!
We haven't had many cold days this winter so I don't know for sure yet. Typically I get a slow rate at first, but in the above example you can see on that cold 17-degree morning it was chilled enough to not charge at all for a while.
I'm still chasing down a reliable measure of actual battery temperature on the can bus, once I have that this will be much easier to answer.
I do have regen limit in kW which is much more informative than a few dotted pixels.
 

JDM3

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So I've finally received the x.50 update and I can say that once the car is warmed up, regen seems to be back to normal. Now it's been hovering around -10C to -15C over the past few days, so I'd be curious if this is due to the rubber hardening on the tires or if it is a true fix. Will post again once I test in warmer temps.

Also, I wanted to get an opinion on winter range loss. I've been noticing significant range loss since the cold weather has kicked in. Here is an example from last night. Temp was -15C. I had 270km of range left and had a 150km drive. Before starting, car was in the garage at about 8C and was plugged and charging. About 20% of the drive was at speeds around 85km/h and the rest was at a consistent 120km/h. When I arrived home I had 32km of range left which means I lost 88km of range (~33% loss). Does that seem right?
 

Mike

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So I've finally received the x.50 update and I can say that once the car is warmed up, regen seems to be back to normal. Now it's been hovering around -10C to -15C over the past few days, so I'd be curious if this is due to the rubber hardening on the tires or if it is a true fix. Will post again once I test in warmer temps.

Also, I wanted to get an opinion on winter range loss. I've been noticing significant range loss since the cold weather has kicked in. Here is an example from last night. Temp was -15C. I had 270km of range left and had a 150km drive. Before starting, car was in the garage at about 8C and was plugged and charging. About 20% of the drive was at speeds around 85km/h and the rest was at a consistent 120km/h. When I arrived home I had 32km of range left which means I lost 88km of range (~33% loss). Does that seem right?
I don't know so I'll do some back of napkin math.

The figure of 149 wh/km is (about) what the fuel/distance-remaining gauge in this car is based on (74.3 kWhs of usable battery capacity applied to a 499 km (EPA) rated range).

Your 150 km drive should use (in an theoretical EPA test environment) (.149 × 150) 22.35 kWhs (30.08% of tank capacity).

Your actual 150 km drive consumed (.149 x 238) 35.46 kWhs (47.7% of tank capacity).

Put another way, instead of .149 wh/km your trip used .236 wh/km (or 58% more than the theoretical rate of use that your distance remaining gauge numbers are based on).

I guess you are asking is a 58% increase in the expected energy used an acceptable premium to run this car at -15c and speeds at 120 kph?

If the headwind situation was not in your favor and/or you were dealing with any precipitation issues, I would expect this performance.

If you had no headwind or precipitation issues, was the terrain hilly?

Do you run your HVAC in set and forget "auto" (which seems to run the a/c compressor in cold climates for some reason)?

o_O

Grumpy old man ranting on a soapbox now: this is why I set my fuel gauge to "% remaing" the day I took delivery 7.5 months ago and have never looked back. The kms/miles remaining numbers only work if you run the vehicle constantly and at EPA test regimen specifications. I gotta go yell at some kids to get off my lawn now!
 

JDM3

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"I guess you are asking is a 58% increase in the expected energy used an acceptable premium to run this car at -15c and speeds at 120 kph?

If the headwind situation was not in your favor and/or you were dealing with any precipitation issues, I would expect this performance.

If you had no headwind or precipitation issues, was the terrain hilly?

Do you run your HVAC in set and forget "auto" (which seems to run the a/c compressor in cold climates for some reason)?
Thanks for doing the math, but yeah, 58% increase seems high to me. I've got a road trip ahead of me that would result in two supercharger stops in normal conditions, now I'm re-thinking about taking my ICE mobile. It wasn't very windy last night, traffic was light as I was traveling at 12:30am and there are hills, but I wouldn't call them mountainous (not sure if you've ever driven on the northbound 400?). I wasn't aware of the HVAC point. Heat was on at fan was set to "2". I can't remember if it was in Auto. I did use my high beams quite a bit during the first 20% run (driving on single lane roads in the country).
 

mswlogo

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Thanks for doing the math, but yeah, 58% increase seems high to me. I've got a road trip ahead of me that would result in two supercharger stops in normal conditions, now I'm re-thinking about taking my ICE mobile. It wasn't very windy last night, traffic was light as I was traveling at 12:30am and there are hills, but I wouldn't call them mountainous (not sure if you've ever driven on the northbound 400?). I wasn't aware of the HVAC point. Heat was on at fan was set to "2". I can't remember if it was in Auto. I did use my high beams quite a bit during the first 20% run (driving on single lane roads in the country).
By my calculations you were ~37% below "ideal range". That's pretty high but -15C going 120 kmh can be tough.

A/C is not the killer. It's the Recirculate Off that is the real killer (which Auto almost always does). Constantly heating -15C air takes a lot of energy.

Low fan speeds save very little and can throw off good measurement for the HVAC.

Sometimes you can run Recirculate On but fogging can creep up on you when you do. You can fight that with A/C and high fan, but when it gets too cold you can't.

Some folks turn seat heaters up and HVAC temp down. Try experimenting with HVAC. It's 99% HVAC that chews up watts when it's cold.

What tires and what tire pressure?
 

Mike

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Thanks for doing the math, but yeah, 58% increase seems high to me. I've got a road trip ahead of me that would result in two supercharger stops in normal conditions, now I'm re-thinking about taking my ICE mobile. It wasn't very windy last night, traffic was light as I was traveling at 12:30am and there are hills, but I wouldn't call them mountainous (not sure if you've ever driven on the northbound 400?). I wasn't aware of the HVAC point. Heat was on at fan was set to "2". I can't remember if it was in Auto. I did use my high beams quite a bit during the first 20% run (driving on single lane roads in the country).
The 58% increase is against the EPA test regimen.

Another way to look at it: what was your burn rate for that same 150 km trip last summer or fall (if you had the car and have that data)?

That real world, non heating season burn rate compared to your .236 wh/km that you just experienced, that would be your true "winter correction" rate for planning purposes.

I've been on northbound 400 and IIRC it isn't level terrain, that's for sure.

As for two supercharger stops in summer versus ???? in the winter for your planned trip, have you tried: https://abetterrouteplanner.com/

Doing the same trip at 110 kph, or simply planning a third supercharger stop may be the required thing to do in the winter........and if you have any "lost regen" dots showing on the left side of the grey horizontal line under the speed readout (indicating a cold battery), the supercharger will be very slow (30 to 40 kW) until your battery is warm enough to handle a large amount of power being dumped into it.
 

Mike

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A/C is not the killer. It's the Recirculate Off that is the real killer (which Auto almost always does). Constantly heating -15C air takes a lot of energy.

Low fan speeds save very little and can throw off good measurement for the HVAC.

Sometimes you can run Recirculate On but fogging can creep up on you when you do. You can fight that with A/C and high fan, but when it gets too cold you can't.

Some folks turn seat heaters up and HVAC temp down. Try experimenting with HVAC. It's 99% HVAC that chews up watts when it's cold.

What tires and what tire pressure?
Good point about the tires (and if aeros are being used), never even thought of that angle.

I will respectfully disagree regarding some of the HVAC points you raise.

IMHO, battery conditioning (until those reduced regen dots are gone) can have a significant impact on energy used in cold conditions.

Once those regen dots are gone, one can actually feel when the HVAC no longer uses resistance heat and is using the scavenged heat from the battery pac.

I leave the fan set to "1" (manual mode, ac off, fresh air only, airflow to windscreen/side windows/floor, set point 18c) and the heat is no longer "toasty hot" once the waste heat from the battery pac is providing the majority of the heating load.

Everyone's driving style is different even if driving at 120 kph on a 400 series highway, but in my (very limited) experience so far this (first) winter, I'm seeing 175ish wh/km on my daily trip odometer for highway trips with those HVAC settings.

The first 20% of the trip is always much worse (>200 wh/km) until the battery is fully warmed up (no limited regen dots) but I always seem to settle back down to the 170s.

Maybe I need more data points (long range trips below -15c) to see if your observations regarding the total impact of HVAC settings have on the numbers are correct and I've just had good luck.
 
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A brief followup to my earlier post about loss of regen in a Mid-Range (Nov 2018 delivery) once I switched to Michelin X-Ice on 18" Aero wheels. Defintely had issues until the 2018.50 update where regen would be very weak and then suddenly kick in strongly at less than 20mph.

Today was my first long run since receiving the 2018.50 update, from the Boulder CO area approx 5200' through the Eiesenhower tunnel at 11,000' to the Supercharger in Silverthorne at 9035' then to Copper Mtn at 9700'. Temp/time stats: The car was charged up starting at 2:30am so at our departure time at 5:30am it showed 99% and 30 min remaining, so the battery was pre-heated. Garage temp was approx 45F/7C, ran the heater while plugged in for about 15 min prior to departure. Ambient temp outside when starting was about 12F/-11C and dropped down to 0F/-17C at the mountain.

Starting out I got the limited regen warning and about 5 dots under the speed indicator for the first 30 min. Once we started climbing, all the dots went away.

During descents and when I had to brake for merging people, it appears I had full regen (green stripe all the way to the left on aggressive slow-downs).

During the return trip, I got *great* regen coming back down to Denver, using less than 20% battery for the whole 100mi return trip. That includes several traffic jams, including the climb from Silverthorne back up to the Tunnel, averaging only 11mph on that climb.

So I'm going to vote for 2018.50 having fixed the majority of the MR + Michelin X-Ice regen issues for me, even though that wasn't really listed as a feature in the release notes.

Now the "Bang"/Big Oil Can sound under the floorboards during low temperature/high-altitude changes is the last remaining "weirdness" with the car, but that's for a different thread.

-=- D. J.
 

JDM3

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if you have any "lost regen" dots showing on the left side of the grey horizontal line under the speed readout
I can honestly say I've never seen these dots. When car is cold I get a snowflake on the screen and a warning that regen may be limited due to cold, but have never seen the dots. Regen always shows a green line (even when I can physically tell there's no regen happening).
 

garsh

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I can honestly say I've never seen these dots. When car is cold I get a snowflake on the screen and a warning that regen may be limited due to cold, but have never seen the dots. Regen always shows a green line (even when I can physically tell there's no regen happening).
If you live in Ontario, then you've seen them. It marks the limit for how far left the green regen bar will go when it's cold.

 

MelindaV

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I schedule charging to start so it ends around when I leave. I always have full regen in the morning.
I do the same, but never have full regen, and assume my temps here are not as low as yours.
Mine is charging 60-90 minutes before I leave, in 50F temp garage, and when I leave have about 6 or 8 dots remaining. The times I had driven further on the prior day, and start charging closer to 2 hours prior, it goes down to 3 or 4 dots, but rarely in the last few months has it been no dots for me.