Disappointed with cold-soak battery range (no garage) Or is it just me?

[Brass Guy]

Preheating the cabin while plugged in will heat the battery if not in range mode. Range mode definitely reduces (if not eliminates) battery heating, plugged in or not.

In my 2013, the battery heater energy use shows up on the dash display. I still have the round gauge center display. With a cold soaked battery, it shows the 6kw use even with climate control off. (Over 10 with cabin heat.) It drops to near nothing when I turn on range mode.

In the past I used range mode to lower my wh/m. If I forgot to turn off range mode, charging would take much longer since the BMS will trickle charge if the battery`s too cold.

The battery heater only seems to heat enough for about 30kw regen, about half the max. Charging always heats the battery, which is why you want to time charging around your departure time. The higher the charge rate, the faster it heats.
If the battery is cold soaked, and range mode is on, it will trickle charge which will take a very long time to heat up.

 

[whitex]

Preheating the cabin while plugged in will heat the battery if not in range mode. Range mode definitely reduces (if not eliminates) battery heating, plugged in or not.

In my 2013, the battery heater energy use shows up on the dash display. I still have the round gauge center display. With a cold soaked battery, it shows the 6kw use even with climate control off. (Over 10 with cabin heat.) It drops to near nothing when I turn on range mode.

In the past I used range mode to lower my wh/m. If I forgot to turn off range mode, charging would take much longer since the BMS will trickle charge if the battery`s too cold.

The battery heater only seems to heat enough for about 30kw regen, about half the max. Charging always heats the battery, which is why you want to time charging around your departure time. The higher the charge rate, the faster it heats.
If the battery is cold soaked, and range mode is on, it will trickle charge which will take a very long time to heat up.

Never tried this while plugged in, but last year on a road trip parked the car outside overnight. The temperature barely hit freezing. As the hotel was near a supercharger, I was going supercharge firs thing, so I cranked the heater to HI and restarted it a few times when it timed out - all together it was heating for about 90 minutes. When I got to the car, I realized I managed to melt some chocolate bars and M&M's I had on the floor (where the new cars had a console). The battery however was completely cold, no regen, and when I got to the supercharger it started at something like 3 or 5KW rate (don't remember what it was exactly, but remembered thinking that a public L2 charger can beat that) and stayed there for few minutes before ramping up.

PS> I don't like driving without regen in the winter, even though I live in Seattle where it doesn't get as cold and I park in the garage. I do find that some hard acceleration helps heat the battery much faster. Not sure whether heating using battery internal resistance takes more or less energy than slowly heating using the heater.At least all the energy from internal resistance is applied to the battery, no inefficiencies there. It gets me regen faster, which is more pleasant for me (I rarely use the brake pedal) and it saves on brake pads.

 

[Brian-MS90D]

Interesting. Is there not a way to just activate the battery heater independently of charging? I don't have a regular daily commute. I may travel 10km one day and then 500km the next. This obviously makes it not impossible but certainly impractical to preprogram (even on a daily basis) charging.

I'd much rather be able to wake up in the morning and start the battery heater then and when I get in the car the battery's ready to go at a reasonable kW consumption. Is that too much of a stretch?

There is no way to start the battery heater other than charging for a time (I don't believe a short time is sufficient) with a 40 amp source or higher (I say this to be safe; I don't think there is an official Tesla released parameter). Your question presents a math equation for which one variable is always changing; thus, there will be no automatic calculating of your always changing schedule. If I were you, I would set up the normal routine for your long trips because that's when it matters. For your short trips, you could choose between:
1. Don't worry about it and be comfortable because you're never going to run out of range.
2. Warm the car up with the cabin heater while plugged in, then turn off the cabin heater when you unplug and depart and rely on heated seats and steering wheel for your 5 minute drive. This will greatly minimize your consumption as the cabin heater consumes a massive amount of electricity (relative to what you are used to in the summer).

I don't worry at all about consumption for my local driving in the winter. Having the car always toasty warm whenever I want it is a tremendous luxury that ICE vehicles cannot do (in many circumstances). I view it as a luxury perk.

 

[Dax279]

There is no way to start the battery heater other than charging for a time (I don't believe a short time is sufficient) with a 40 amp source or higher (I say this to be safe; I don't think there is an official Tesla released parameter). Your question presents a math equation for which one variable is always changing; thus, there will be no automatic calculating of your always changing schedule. If I were you, I would set up the normal routine for your long trips because that's when it matters. For your short trips, you could choose between:
1. Don't worry about it and be comfortable because you're never going to run out of range.
2. Warm the car up with the cabin heater while plugged in, then turn off the cabin heater when you unplug and depart and rely on heated seats and steering wheel for your 5 minute drive. This will greatly minimize your consumption as the cabin heater consumes a massive amount of electricity (relative to what you are used to in the summer).

I don't worry at all about consumption for my local driving in the winter. Having the car always toasty warm whenever I want it is a tremendous luxury that ICE vehicles cannot do (in many circumstances). I view it as a luxury perk.

I could not agree with this quote more and just think that you should plug in at home and at work. Set your charge so that it completes your desired level of charging just before you leave. This way, at least the battery will be earned a little and while you may not get full regen, you hopefully will see it improving quicker during your commute.

 

[Brass Guy]

I don't think there's a link between how much current you're charging with and the battery heater. I'm not certain, but pretty sure that if you plug into a 120V 15A (for example) circuit, and the battery heater turns on, you will lose range rather than add to it.

 

[mspohr]

I'm not sure why people are concerned about preheating the battery.
Any range that is "lost" due to a cold battery is regained as soon as it warms up during normal driving.
The only downside of a cold battery is that regen is limited.

 

[David29]

Lots of good tips. Those that don't know what cold is -- it got several times below 0F in Chicago last winter and I only exceed 400kwh per mile average once.

The only advice I can add is to try to evenly draw power from the battery (AP is great at this). Don't floor it and then try to regen back as it will be very inefficient at both producing power (sometimes you'll be power limited due to cold as well as regen limited).

Start regen braking far further out than usual. Regen, even if 10kw, will help warm the battery and make your drive more efficient. Since regen will be limited, you'll need more distance to stop but you should be able to capture most of your KE into PE again (and warm the battery in the process).

Consider using the cabin pre-heat from app as it will draw tons of power (6kw for PTC heater!) but if you do it for 15 minutes, you'll only use at most 2kw but it will result in a more efficient drive overall and you'll be happier). Sometimes 2kw makes a big difference on how you feel about losing efficiency in the winter (as in, you'll be warm so you might not care anymore).

My lifetime average after 1 full year (of Chicago weather) is 281wh/mi which is below the rated average. I never use cabin heat when alone but with my child, I use it to take the chill off (and if that's >15 minutes the PTC draw usually drops to 1-2kw so I might keep it on).

Just remember, this isn't even winter yet. You might stop caring about being efficient once it gets truly bitter cold but these things also even out over the year.

Very impressed by your low lifetime average energy consumption! Mine is more like 325 or so, and winter here is mild compared to Chicago! I guess I am a wimp, though -- I do use cabin heat even when driving alone.

My car is parked outside. You did not say if yours is or not -- that could make a huge difference in your starting condition each day.

Also, I am retired so I make lots of short trips and have no regular daily commute. As others have said, longer trips are more efficient for cabin heating/cooling as well as better for regen and efficiency.

 

[David29]

I'm not sure why people are concerned about preheating the battery.
Any range that is "lost" due to a cold battery is regained as soon as it warms up during normal driving.
The only downside of a cold battery is that regen is limited.

If I understand you correctly, I disagree. First off, when a cold battery limits regen and you need to slow or stop the car, you forever lose any energy that could have been regained by use of regen and goes instead into heat loss from the service brakes. You can't "regain" that energy later.

Second, when regen is limited, the car does not behave as I have come to expect it to. I have to be extra vigilant about using the service brake when needed. And yes, every ICE driver has to brake that way and everyone should be ready to, but once in a while I am a bit surprised that the car does not decelerate when I lift my foot off the accelerator, especially in those first few cool fall days when I encounter regen limits for the first time in a season. So avoiding those limits is, for me, a safety advantage.

 

[mspohr]

If I understand you correctly, I disagree. First off, when a cold battery limits regen and you need to slow or stop the car, you forever lose any energy that could have been regained by use of regen and goes instead into heat loss from the service brakes. You can't "regain" that energy later.

Second, when regen is limited, the car does not behave as I have come to expect it to. I have to be extra vigilant about using the service brake when needed. And yes, every ICE driver has to brake that way and everyone should be ready to, but once in a while I am a bit surprised that the car does not decelerate when I lift my foot off the accelerator, especially in those first few cool fall days when I encounter regen limits for the first time in a season. So avoiding those limits is, for me, a safety advantage.

I agree about regen (which I mentioned).
I was referring to battery range which is regained as the battery warms up.

 

[David29]

I agree about regen (which I mentioned).
I was referring to battery range which is regained as the battery warms up.

Ah. Thanks for that clarification.

 

[RDoc]

I'm not sure why people are concerned about preheating the battery.
Any range that is "lost" due to a cold battery is regained as soon as it warms up during normal driving.
The only downside of a cold battery is that regen is limited.

Because the range lost heating the battery from battery current is gone permanently.

 

[mspohr]

Because the range lost heating the battery from battery current is gone permanently.

The "battery current" drives the car so is not lost.

 

[croman]

Very impressed by your low lifetime average energy consumption! Mine is more like 325 or so, and winter here is mild compared to Chicago! I guess I am a wimp, though -- I do use cabin heat even when driving alone.

My car is parked outside. You did not say if yours is or not -- that could make a huge difference in your starting condition each day.

Also, I am retired so I make lots of short trips and have no regular daily commute. As others have said, longer trips are more efficient for cabin heating/cooling as well as better for regen and efficiency.

My car is garaged and it's an attached 2.5 car garage. It's not heated but yes, but having a completely cold soaked battery helps a lot. I also drove 60% of my miles during the warmer months. But I am battle hardened from 3 years of leaf ownership.

I also commute 28 miles each way so that gives my battery plenty of time to get more efficient. I also have taken 6 long road trips totaling about 8k miles and they help keep my average lower than my daily winter average suggests. I think I average 318 wh/mi in winter. More if family needs heat.

 

[aesculus]

I'm not sure why people are concerned about preheating the battery.
Any range that is "lost" due to a cold battery is regained as soon as it warms up during normal driving.
The only downside of a cold battery is that regen is limited.

No. Range that is lost because the battery is cold and then naturally reheated is regained. But any power used to heat the battery is gone. It was used up as heat and cannot be recaptured.

 

[brkaus]

When I really need the range for a day (not frequently), I bump the charge % limit 30-60 min before I need to leave. The charging will heat the battery. It also reduces the time the car sits at a high charge.

Regarding this -

Any range that is "lost" due to a cold battery is regained as soon as it warms up during normal driving.
The only downside of a cold battery is that regen is limited.

I do not believe it to be totally true. Some of the energy is going to the heater that warms the battery. That energy towards heating is never recovered.

 

[mspohr]

When I really need the range for a day (not frequently), I bump the charge % limit 30-60 min before I need to leave. The charging will heat the battery. It also reduces the time the car sits at a high charge.

Regarding this -



I do not believe it to be totally true. Some of the energy is going to the heater that warms the battery. That energy towards heating is never recovered.

I think the battery heater only comes on in Range Mode.

 

[croman]

I think the battery heater only comes on in Range Mode.

No range mode eliminates battery heating. The battery is most efficient above 20C. I believe wk057 said 30-50C is the peak operating range.

As others have said, the net gain from battery warming means using some energy to warm the pack results in a net gain of range but that energy is, indeed, used (but not wasted as long as the trip duration is such that the energy expended is actually realized as range gain).

 

[brkaus]

No range mode eliminates battery heating. The battery is most efficient above 20C. I believe wk057 said 30-50C is the peak operating range.

I really wish there was some sort of better spec on range mode.

My understanding is that there is a ideal battery temp range and an OK range. The car tries to keep the battery in the ideal temp, but in range mode it just goes for the OK temps... that saves energy on heating/cooling the battery.

Let's say ideal is 30-50C as you mentioned.

Then OK might be 20-60C.

Of course, totally pulled from the sky (with unicorns flying past). I think I read it here somewhere, but cannot find any references so not sure.

 

[mspohr]

No range mode eliminates battery heating. The battery is most efficient above 20C. I believe wk057 said 30-50C is the peak operating range.

As others have said, the net gain from battery warming means using some energy to warm the pack results in a net gain of range but that energy is, indeed, used (but not wasted as long as the trip duration is such that the energy expended is actually realized as range gain).

There seems to be a lot of confusion about range mode.
This post says it heats the battery to a higher temperature.
What does Range Mode? | Tesla

 

[brkaus]

There seems to be a lot of confusion about range mode.
This post says it heats the battery to a higher temperature.
What does Range Mode? | Tesla

Agree!!!