Interesting finding about Range Mode

[jerry33]

so reading thru this thread, i should leave range mode on in the summer (very hot here in so cal 90F-105-110F summers) which really seems to help conserve battery life

But in the winter (temps 32F-50F) should i leave it off? 75D AP2 car. It was 55F outside with range mode ON during a 50 mile drive and final range was 32 miles left _ I got this warning:

battery low there will be significantly less energy if it gets colder we recommend charging now. (which I did since I was back home).

Summer : range mode ON
Winter: keep range mode OFF?

I've found just the opposite. It does almost nothing in the summer here in Texas (where it's warmer than in California). In winter, when the temperature is 17C or lower, turning it on helps a great deal in short trips. On long trips the benefit is slight, and be sure to remember to turn it off when charging to warm the battery. Preheating and setting the charging to end shortly before you start to drive also works well in winter. I've used this technique in Canada during winter (on a trip) and didn't see anything that would lead me to believe that it isn't correct.

In addition, having range mode on in summer limits the cooling to the battery somewhat, so the battery is allowed to get warmer before the cooling kicks in. I get reasonably Wh/mi so the way I use range mode appears to work for me.

 

[dgpcolorado]

...In winter, when the temperature is 17C or lower, turning it on helps a great deal in short trips...

I'm puzzled by this. For short trips range isn't limiting so what useful difference does range mode make?

I've never really figured out a good use case for range mode, so I leave it off. I want my battery warmer in winter to reduce the loss of regen (needed for very steep hills) and cooler in summer to protect it — I'll just drive a bit slower or turn cabin climate control off if range is limiting, which is quite uncommon. I must be missing something because I just don't "get" range mode.

 

[David99]

so reading thru this thread, i should leave range mode on in the summer (very hot here in so cal 90F-105-110F summers) which really seems to help conserve battery life

But in the winter (temps 32F-50F) should i leave it off? 75D AP2 car. It was 55F outside with range mode ON during a 50 mile drive and final range was 32 miles left _ I got this warning:

battery low there will be significantly less energy if it gets colder we recommend charging now. (which I did since I was back home).

Summer : range mode ON
Winter: keep range mode OFF?

I've generally been leaving it on with the general feeling it seems to help (it's socal we use the AC 90% of the time).

Warm temperature is good for battery performance but bad for longevity. A cold battery performs less, has a higher resistance, is capable of less output and when pushed hard, the battery gets damaged. When the battery is 'idling', low temperatures are good, as the chemical process is slowed down thus less degradation.

For driving, charging and to be able to get the most energy out of the battery you want it warm. A warm battery has a lower resistance and higher efficiency. You get higher power rates and more energy out of it. It gives and takes charge better. But the degradation is higher.

Range mode doesn't use the battery heater, it just redirects the heat from the inverter and motor and DCDC converter into the battery until it reaches a higher temperature than it would without range mode on. If you live in a warm climate, Range Mode might not make much of a difference, though. Because of the high ambient temperature the battery will get warmer anyways.

 

[jerry33]

I'm puzzled by this. For short trips range isn't limiting so what useful difference does range mode make?

It reduces the amount of energy you use. And it could be range limiting. For example: Let's say you're a real estate agent or something similar where you make many short trips all day long. In this case, range mode can make the difference between having or not having to charge during the day.

 

[rhumbliner]

Warm temperature is good for battery performance but bad for longevity

Most academic studies tend to focus on the number of recharging cycles as the main culprit in battery degradation — not operating temperature. We all seem to agree that too high temperatures age a battery (as well as too cold) but there doesn’t seem to be a consensus on what is too high or too low, or conversely, what’s the perfect operating range. Similarly I’ve yet to see anything definitive on how quickly a lith-ion battery degrades solely with regard to temperature.

TMC has several threads on this subject and there don’t seem to be any simple answers. This is obviously a complex topic and we’ll just have to accept our position as bleeding-edge pioneers. For now, I’m happy to let the Tesla battery experts control the temperature range with the hope they know more about the subject than I.

 

[David99]

Most academic studies tend to focus on the number of recharging cycles as the main culprit in battery degradation — not operating temperature. We all seem to agree that too high temperatures age a battery (as well as too cold) but there doesn’t seem to be a consensus on what is too high or too low, or conversely, what’s the perfect operating range. Similarly I’ve yet to see anything definitive on how quickly a lith-ion battery degrades solely with regard to temperature.

TMC has several threads on this subject and there don’t seem to be any simple answers.

The thing is there is no ideal temperature. Both low temps and high temps have advantages and disadvantages. To get the best performance, lowest internal resistance and most energy out of the battery, a high temperature is better. But it comes with the disadvantage of causing higher degradation. Low temperatures keep the battery live longer but it operates less efficient. These are opposing attributes so there is no ideal. It's always a compromise.

 

[rebra]

I use range mode in winter (at least when it's below freezing) when driving short distances. This is mainly to reduce the energy spent to warm up the battery, as there will be no benefit of spending energy to warm up the battery pack slightly just before parking. Lack of regen is good as it makes you use the brakes to get the small layer of rust off.

 

[gavine]

I'm puzzled by this. For short trips range isn't limiting so what useful difference does range mode make?

For short trips (when it's cold), range mode warms the battery to enable regen which can net more energy than no battery warming with no regen. If your trip is short, then the only benefit is saving energy since range isn't really an issue.

I've never really figured out a good use case for range mode, so I leave it off. I want my battery warmer in winter to reduce the loss of regen (needed for very steep hills) and cooler in summer to protect it — I'll just drive a bit slower or turn cabin climate control off if range is limiting, which is quite uncommon. I must be missing something because I just don't "get" range mode.

Plain and simple explanation. If you're going on a very long trip and will be getting on the highway early-on, there's no reason to spend energy warming-up the battery for enabling regen, when you're likely not going to need regen since you will be on the highway. In the summer, it mostly just limits the AC power.

 

[gavine]

It reduces the amount of energy you use. And it could be range limiting. For example: Let's say you're a real estate agent or something similar where you make many short trips all day long. In this case, range mode can make the difference between having or not having to charge during the day.

Not necessarily the case, depending on how short the trips are, but if the battery pack is cold, those short trips with range mode on will not warm the battery to enable regen so you'll be losing-out on a lot of energy recapture potential. Plus you'll use the brakes much more, adding wear to them.

Warming the battery might use 3 to 5 kW, but regen can be 60kW so Tesla decided that, in most cases, spending energy to warm the battery is worth it in the potential regen gain. These short trips of yours will likely net positive from the battery warming energy with range mode off.

Now, if you're just going to a convenience store a mile away, it's not worth it because it does take time to warm the battery and you likely recover the spent energy warming the battery.

 

[scaesare]

I think lots of people are over thinking this, and trying to second guess what the engineers designed the car to do.

How about: If I'm not absolutely pushing the limits of range.. don't' enable range mode. The car is designed to keep itself, and passengers comfiest.

If I really need extra range... enable range mode! This helps more in cold than heat.

SImple, really.

 

[David99]

There is one misconception here! Range Mode sets the target temperature higher. It does not activate the battery heater to do so. The heat from motor/inverter/DCDC converter are used to heat the battery to a higher point. Range Mode does not use more energy by using the battery heater. That would totally defeat the purpose. Range Mode just keeps pumping the excess heat from the drive unit into the battery until it reaches aprox 40 Celsius. Without Range Mode, the car does the same but stops putting the excess heat into the batter at 30 Celsius. It doesn't use more or less energy to get the battery warmer it just directs the excess heat into the battery longer.

The battery heater is activated when the battery temperature drops below aprox 10 degree Celsius. The car does that regardless of Range Mode settings.

 

[rebra]

@David99, I think you are mistaken. In cold temperatures with range mode _on_, the car will not use the battery heater to heat the battery. With range mode _off_, it will use the battery heater to get the temperature up to a certain point. Hence the wasted energy for short trips, where you will not get much benefit of regen.

This is easily confirmed by a simple experiment in cold weather.

Edit: You _are_ correct that range mode will not heat the battery to achieve the higher temperature.

 

[jgs]

Warming the battery might use 3 to 5 kW, but regen can be 60kW

kW are not the right units to use here -- kWh are, since you're talking energy, not power. Sure, regen can net 60 kW but over relatively short timespans unless you're going down a mountain. It only takes 12 seconds of pack heater at 5kW to use up the energy you capture in 1 second of hard regen.

 

[David99]

@David99, I think you are mistaken. In cold temperatures with range mode _on_, the car will not use the battery heater to heat the battery. With range mode _off_, it will use the battery heater to get the temperature up to a certain point. Hence the wasted energy for short trips, where you will not get much benefit of regen.

This is easily confirmed by a simple experiment in cold weather.

Edit: You _are_ correct that range mode will not heat the battery to achieve the higher temperature.

I don't have too much winter driving experience myself living in Los Angeles. I did notice that the battery heater stops once the battery has reached around 10 Celsius (50 F). I wonder if Range Mode just sets this threshold lower. I can't test it here. DOesn't get cold enough

 

[gavine]

kW are not the right units to use here -- kWh are, since you're talking energy, not power. Sure, regen can net 60 kW but over relatively short timespans unless you're going down a mountain. It only takes 12 seconds of pack heater at 5kW to use up the energy you capture in 1 second of hard regen.

I was talking power. The meter on the dash shows 3 to 5kW of power use when the battery warmer is working. The amount of kWh would depend on how cold-soaked the battery is and how cold the ambient temperature is.

 

[Rocky_H]

kW are not the right units to use here -- kWh are, since you're talking energy, not power. Sure, regen can net 60 kW but over relatively short timespans unless you're going down a mountain. It only takes 12 seconds of pack heater at 5kW to use up the energy you capture in 1 second of hard regen.

I am really trying to be polite, but everything in this is wrong. kW is the right unit. It is talking about power; not energy. And the regen meter is showing up to 60kW of instantaneous power usage. It is the rate of energy use. Sheesh, a wrong correction got two likes.

 

[jgs]

I was talking power. The meter on the dash shows 3 to 5kW of power use when the battery warmer is working. The amount of kWh would depend on how cold-soaked the battery is and how cold the ambient temperature is.

At least on those factors, and probably more. Likewise, the kWh recovered by regen depends on the route being driven, driving style, road conditions, traffic, and so on. In any case, while I accept that you did intend power and not energy in your units, even after rereading the post I still think it's misleading to be talking in units of power, and the point you're making is ultimately about energy of course:

Not necessarily the case, depending on how short the trips are, but if the battery pack is cold, those short trips with range mode on will not warm the battery to enable regen so you'll be losing-out on a lot of energy recapture potential. Plus you'll use the brakes much more, adding wear to them.

Warming the battery might use 3 to 5 kW, but regen can be 60kW so Tesla decided that, in most cases, spending energy to warm the battery is worth it in the potential regen gain. These short trips of yours will likely net positive from the battery warming energy with range mode off.

Now, if you're just going to a convenience store a mile away, it's not worth it because it does take time to warm the battery and you likely recover the spent energy warming the battery.

My point was not to be a know-it-all about unit analysis, but to point out that looking only at power units can be deceptive, since "60 kW > 5 kW therefore pack heating is good!" isn't a reasonable conclusion without considering the time part of the equation -- how much time are you capturing that 60 kW for, how much time are you spending that 5 kW for? But even though the complete set of potential factors is huge, a simple rule of thumb is, as long as you're not touching the brake pedal, you're not missing out on any recapture even if regen is limited. So, if conditions allow you to adjust your driving so you don't have to touch the brake pedal (much), there's no need to heat the pack. FWIW, for my purposes I usually find I can do this.

BTW I think it's a little too simplistic to say "Tesla defaulted the heater on which must mean they think you can save energy that way." It could as easily be that the engineer who decided to do it that way wanted to get the most consistent driving experience possible out of the car and considered it OK to spend a few joules to do it. I don't know.

I am really trying to be polite,

Thanks for trying!

but everything in this is wrong.

Can you explain what about "It only takes 12 seconds of pack heater at 5kW to use up the energy you capture in 1 second of hard regen" was wrong?

kW is the right unit. It is talking about power; not energy. And the regen meter is showing up to 60kW of instantaneous power usage. It is the rate of energy use. Sheesh, a wrong correction got two likes.

I went back and reread the OP pretty carefully and I'm not convinced that it was a "wrong correction", see above.

 

[Rocky_H]

Can you explain what about "It only takes 12 seconds of pack heater at 5kW to use up the energy you capture in 1 second of hard regen" was wrong?

I do apologize. That last sentence was separate from your attempted correction, and standing by itself, is accurate, so I should not have said "everything".

 

[jgs]

I do apologize. That last sentence was separate from your attempted correction, and standing by itself, is accurate, so I should not have said "everything".

Thanks. For that matter, I suppose you don't take issue with "regen can net 60 kW but over relatively short timespans unless you're going down a mountain." I guess you were really disagreeing with the first sentence, about units of energy being preferable to units of power for this discussion, about which I suppose we continue to disagree.

 

[Rocky_H]

I guess you were really disagreeing with the first sentence, about units of energy being preferable to units of power for this discussion, about which I suppose we continue to disagree.

I don't think anyone but you thinks that was about what was "preferable". You told @gavine he didn't know what he was talking about--not cool. Anyway, we should probably leave this alone pretty soon before mods think we need to stop talking.