Question to the battery experts concerning range mode

[CygnusX1]

Hi,

I get quite high energy consumption while driving in cold weather. Example: 41 mi, 40 F, 65 mph mostly highway => 340 Wh/mi. Sounds not that high, but: That is with cabin temp set to 66 F and seat heater set to 1, so no too comfortable... The car is pre-heated for about 10 min which is enough to get the interieur warm but not the battery of course.

In the energy app I see a broad peak at the beginning of the drive which I interpret as the energy consumption of the battery heater. This peak offsets my average...

I never tried to set range mode to "on" because I don't know if that is bad for the battery life. If the battery isn't heated actively, it longer stays in a condition where it has limited performance (regen and max power). But that wouldn't be much of a concern to me. And I wouldn't mind the reduced power of the cabin heater, too.

So the question is: Does "range mode off" help to reduce battery "wear" in cold weather, or is it just for the convenience of having full regen and full power more quickly? Or put it the other way round: Can I use "range mode on" without any technical concerns?

Thanks,
Bernd

 

[Johan]

Range mode isn't bad for battery life. It does use the battery heater if necessary but, like you allude to, does have a bit higher tolerance for driving around with a colder battery. If anything this prolongs battery life, seeing as a cold battery degrades less and as limited power draw and regen is a bit of "pampering" for the battery. With regards to actual range achieved though it's a bit double edged: if your battery is quite full and you intend do drive for a long time it will heat up eventually (unless it's very very cold in which case the heater will have to come on) and all the range will be made available to you. If the battery is low when you start driving it might result in better range if it's quickly heated up, since a cold soaked battery will be able to deliver less total charge before its voltage gets low ("0% state of charge").

TL;DR: Range mode if anything reduces battery wear, it can be used all the time without concern.

 

[CygnusX1]

Thanks Johan for your reply,

so you are saying that even range mode uses the battery heater in very extreme conditions, but not as early as RM off?

I will give it a try and see if I can get my consumption lower. My aim is getting below 320 Wh/mi, 300 would be great (186 Wh/km)... This would give my S70 a max range of 350 km (218 mi).

I see you're from Drammen, Norge! We're planning a holiday vacation in Norway this summer! With our Tesla, of course... Just checking Type2 chargers in your country and how to get access to them.

 

[Johan]

Thanks Johan for your reply,

so you are saying that even range mode uses the battery heater in very extreme conditions, but not as early as RM off?

I will give it a try and see if I can get my consumption lower. My aim is getting below 320 Wh/mi, 300 would be great (186 Wh/km)... This would give my S70 a max range of 350 km (218 mi).

I see you're from Drammen, Norge! We're planning a holiday vacation in Norway this summer! With our Tesla, of course... Just checking Type2 chargers in your country and how to get access to them.

This isn't properly documented anywhere, not by Tesla anyway, but I believe the battery heater will only come on when driving in range mode should the battery get very cold i.e. close to stop working properly, with severe drop in range as a result (i.e. defies the purpose of range mode). So you could say range mode increases range by cutting down on cabin heating as it's main modus operandi, and less convenience in the form of a higher change of reduced acceleration and regen in the first part of the drive (could last for a long time if it's cold).

If it's cold, for optimal range you should turn range mode off and do the last bit of charging just before you leave, then turn range mode on as you start driving (the battery will be preheated).

I never use range mode.

Also check out Ladestasjoner.no where you can filter for type 2 chargers.

 

[jbcarioca]

As another aside, if you charge using any fat charger the battery will heat up during the charge so not needing to use battery power to do that. The colder the temperature is the grater the advantage of charging just before driving, including preheating the car interior. I'm sure you already know all about that. I find my cold (<0C) weather efficiency on long trips is only about 5/6% lower than in warm (>15C) conditions when I follow that process. When the weather is cold I try to plug in to any power I can find, even level 1, when I stop, just to keep the battery and the interior warm.

I am positive Johan knows vastly more than I do about such issues, so I am a bit reluctant to even make these comments.

I use range mode almost all the time except when the weather is very hot.

 

[CygnusX1]

I thought that charging a cold battery usually invokes the battery heater? When I plug in the Tesla with cold battery, it draws the typical 16 amps (I have a 11 kW Type2 home charger) but the charging speed shown in the app at the beginning lies below 51 km/hr (which is the reading I get when the battery is warm). I interpret that as the power used by the battery heater which subtracts from the 11 kW supplied from the grid.

Therefore, I usually charge the car in the evening after returning from work when the battery is still warm. Maybe I do some thinking errors here?

 

[gracchus]

Interesting commentary on range mode, Johan. Wouldn't there be some kind of balance between the degree to which acceleration and regen are reduced, and the effect of range mode on the battery? I've always wondered why acceleration is mostly unlimited compared to regen, which is severely limited by cold. Is that because discharging is less hard on the battery than charging at the same power? Or is it because regen is more of an optional benefit whereas acceleration is more needed for driving?

 

[Rocky_H]

I've always wondered why acceleration is mostly unlimited compared to regen, which is severely limited by cold. Is that because discharging is less hard on the battery than charging at the same power?

It's just the chemical nature of lithium ion batteries. The chemical reaction to discharge energy out of them can be fine and non-harmful at cold temperatures (to a point), but it causes permanent damage to charge them up (or charge too fast) when they are very cold.

 

[johnmull]

Hmm. My usage is well over 400 (440 wh/mi) even though I drive the car exactly the way I drove my hybrid with which I routinely got 45 mi/gal, and had a high of 48 mi/gal. Why is my consumption so much higher than any posted here? It is winter and I live in Connecticut but the car wasn't driven for most of Jan/Feb. Given the electricity current electricity rates and gas costs, I am getting the equivalent of 21 mi/gal. So this car is costing me far more I expected, a rather unpleasant surprise.

I have a Model S 100D with 930 miles on it. Range mode is on as is a single heated seat, single bar and cabin temp is 70. I don't use the heated steering wheel. All my driving thus far is urban, no highway. Is something wrong with this car? If so how would I tell?

 

[N..8]

Even with Range mode on the battery heater may come on depends on temps. Since your doing a lot of shorter trips you are really getting hit hard. I commute 30 miles and the first 15 miles I can sometimes hit 400 wh/mi. With the battery heater on it's about a 30% hit in range for me if it's cold.

 

[tnt1971]

Short trips, in the cold, is where it helps a lot. I am a hockey dad, and I have taken the car to many tournaments. When I get to the destination, and there is no supercharger nearby, it causes some angst. I turn on the low power mode and range mode and don't use the heater for short trips to and from the rinks, dinner, etc. It helps, but the long term solution is more chargers. Because we stay at the hotel with the team, they don't select hotels with destination chargers most times.