Preconditioning the i3 a cold winter day and effect on range

A great function on the BMW i3 is that it can be preconditioned. It can be started by setting a time in the car or through the iRemote app. It  can also be started immediately using the key or iRemote app.

The preconditioning will warm the cabin as well as the battery. Warming the battery will increase range and heating the cabin will make the ride more comfortable (and increase range if you were preconditioning while the car was still plugged in).

Setting up preconditioning

The preconditioning can be started in the iRemote app (iOS or Android). Immediate preconditioning is started by pressing the fan symbol at the bottom and the press “Activate preconditioning”. Alternatively a timer can be set by pressing the clock symbol and then enter a specific time. This timer can also be set up to be repeated specific days of the week, e g all Mondays or all working days. Do not forget to press the ok button in the top right corner to active and send the command to the car. The timer can also be set in a similar way from within the car using the iDrive.

iRemote Precondition Immediate iRemote Precondition Timer

Personally I often start the immediate preconditioning through the iRemote app. This is great if I just ended a meeting and have a block or two of walking to the car.

Living in Stockholm, that occasionally has some very cold winter days, I use the preconditioning a lot . However, to go through all the steps in the iRemote app and making certain that the command is sent from the BMW server to the car takes a little bit of time (and it has happened that there is an error in the communication). I have therefore also programmed the button on the key to immediately start the preconditioning. What this button is doing can be set up using the iDrive in the car.


Important time limits

If a time of departure has been set at least three hours in advance, the high voltage battery will also be preconditioned. If immediate preconditioning has been initiated or the departure time is less than three hours away the HV battery will not be preconditioned at all. Also, the car has to be plugged in for the HV battery to be preconditioned (but it can be to a normal 120V or 240V).

It can also be noted that both preconditioning (cabin and battery) are using power from the HV battery, but if the car is plugged in it will start charging the battery. However, if the car is plugged in with only a standard charger the preconditioning will use more power (approx. 4000W) than what the car is able to draw from the socket and the car will hence not be fully charge at the time of departure.

Finally, the cabin preconditioning is only active for 30 minutes so starting too early may result in a cold car.

Nick, a BMW i Concierge at, has created a great Preconditioning Q&A.

Time to a warm the cabin

In my experience the cabin preconditioning makes a difference even if it has only be turned on a few minutes before departure. The cabin is warmer and since the hot air is blowing against the windshield it has often saved me from scraping ice.

To give you an idea I measured the temperature during a cold Scandinavian winter day. The thermometer showed -15 degrees Celsius (about zero Fahrenheit). The cabin preconditioning was turned on and the temperature was measured in the middle of the driver backrest and rear seat backrest.

PreheatedDriverSeat PreheatedSeat

The result shows that the driver seat temperature increased 15 degrees (to 0C, 32F) in about 10 minutes (blue line) while the rear seat took a minutes more (orange line). The first five minutes the fan was only working at very low speed and after 30 minutes the preconditioning is stopped. The air blowing on the windshield measured about 35 degrees Celsius (almost 100 F).

Pre heating temperature 3 604x270

The energy used to preheat the cabin is about 1 kWh for 10 minutes and 3 kWh for 30 minutes. This suggest that the effect is actually about 6000W rather than the 4000W I have seen in other forums.

The estimated range reduction (as reported by the i3 itself) is about 3 km for 10 minutes of preconditioning and 9 km for 30 minutes. As always this must be taken with a grain of salt as this is based on only one data point and the range estimation itself is a science that is influenced by many parameters. Above all it should be remembered that this was during a cold winter day (-15C, 0F) and with the car in comfort mode. Also by preconditioning the car it may be possible to reduce the heat during the ride and hence compensate for the energy used to preheat.

EDIT: Just tested to set the timer for this morning. The cabin temperature was similar to the immeadete cabin preconditioning described above. The battery temperature, however, was now +8C (46F) instead of the outside -10C (14F). 30 minutes after the preconditioning ended the cabin temperature had dropped significantly but the battery temperature was only down one degree. Another 30 minutes later the battery temperature was down to +5C (41F). Since I only use a standard charger at home and limited it 2000W the battery level (SOC) was 97% at the set departure time.



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22 thoughts on “Preconditioning the i3 a cold winter day and effect on range

  1. Hi,

    I want to share a humble hint of my practice. Charging our i3 is my honorable duty (-: and as İstanbul (my hometown) is not so cold and snowy I prefer plugging in our i3 just after midnights in our condo’s underground garage. By this routine my wife has a chance to unplug it in the mornings when the battery is near full and rather warm.
    This detail helps us to avoid a fully charged battery as well as a cooling down (or cold) HV battery.
    PS: Excepting winter days I don’t bother with this timing issue. (-;

  2. Nice article, thanks for your work!

    I have read somewhere, that there is not enough heat recoverable from the heatpump under ~-5C°, so resistive heating is used then with much higher consumption impact. There is only resistive heating (integrated into the battery compartment) used for the battery, therefore available if plugged-in only.

    1. Thank you for the info, ACMik. Air source heat pumps certainly have lower performance in cold weather (COP = Coefficient of performance). While there are stationary models that can produce heat from very cold ambient air (some reaching a COP of 1 as low as -32C) it can probably not be expected from a small mobile heat pump inside a car. Do you know the source of the -5C statement? It would be interesting to get some COP data for the BMW heatpump in different ambient air temperatures.

      1. All I can now find is this statement from BMW University I01 Heating and A/C Systems:

        “The operation of a heat pump in all its operating modes makes sense in a temperature range between–10 °Cand+40 °C/14 °Fand+104 °F.”

        5.1.Prerequisites for stationary cooling
        The stationary cooling can only beoperated when the following preconditions are satisfied:
        • The high-voltage battery is sufficiently charged
        • The vehicle is connected to a chargingstation
        • The charging power at the power socket must be at least 1.5 kW
        • Windows and doors should be closed to increase the efficiency.

  3. Justed added some experience from preconditioning the battery by setting the timer. See end of the post above.

  4. The energy used to preheat the cabin is about 1 kWh for 10 minutes and 3 kWh for 30 minutes. This suggest that the effect is actually about 6000W rather than the 4000W I have seen in other forums.

    Do you mean 1 kW for 10 mins (0.15kWhr) and 3kWhrs for 30 mins (1.5kWhrs). Total 1.65kWhrs.

    Typical in the UK for precon is 1 to 1.5 kWhrs.

    1. Hi David,

      No I mean 1 kWh for 10 min and 3 kWh for 30 minutes. At that rate it will use 6 kWh each hour and that means that the power is 6 kW (6000W).

      Yes, in warmer weather I believe 1 to 1.5 kWh is about right, but this was a test done in -15 degrees Celsius to show how well the i3 is doing in cold Nordic weather. As ACMik has pointed out the heat pump is probably not very efficient at this temperature and the resistive heater is probably working at its maximum.

      1. Thanks. If you mean 1 KWhr for 10 minutes then the power is 6kW – 6kW for 10 minutes is 1kWhr. The difficulty I have with that is that the precon battery heater is only 1kW and it doesn’t run for long otherwise it would contort the battery pack as it takes a while for the heat to soak through.
        The cabin heating can be as high as 5.5kW and cabin heating can run for 30 minutes so will use up to 2.75kWhrs but rarely does.
        I know that the UK is warmer in winter than Sweden but I have a precon trac for -20degC in Canada. The total energy used is about 1.75kWhrs with the first 10 min/1kW peak in the first hour and another similar in the second hour followed by the cabin heating in the last 30 mins.

        1. Hi David
          Thanks for clarifying – I believe I now see the misunderstanding. The energy and seat temperature in the graph above as well as the 6 kW power mentioned ONLY concerns the cabin preconditioning. The resistive heater is 5.5 kW and maybe there is more power used by something else. Fans? The preconditioning of the battery may use lower power – I have not come around to test and measure that (yet).

          1. OK, I see the misunderstanding.

            In the UK at the moment it’s minus 6 degC and my 3-hour pre-con was 3-kWHrs instead of my normal 1.5kWHrs.

            There are a couple of graphs posted on the forum from someone called Rodham in Canada who has monitored the power and energy and posted the graphs. I can send them to you so you can compare them when you do your test.

  5. Hej! Tack för en superbra informativ blogg!! kanon! Fortsätt med denna!
    Jag undrar lite över hur föruppvärmning fungerar..Säg att jag idag kl 18 ställer in avresetid i morgon bitti kl 07,och har bilen på laddning i garaget (med “vanlig” hushållskontakt) Blir då batteriet uppvärmt+att resandeutrymmet ochså värms upp tills jag ska avresa? dvs startar värmning av kupe i lagom tid ex 30 min innan kl 07 så den är varm när jag ska åka vid 07? sköter bilen av detta värmande själv i rätt tid till avresa?/Thomas

    1. Thank you Thomas!
      If you set a departure time more than three hours in advance the battery preconditioning will generally start 180 minutes before departure and then switch to cabin preconditioning about 30 minutes before departure. It will do it automatically and adjust the times to the outside temperature. The power for the preconditioning will come from the High Voltage battery, but it will start charging from your outlet. However if you use a normal socket the maximum power is 2500W (at least in Europe) and this is less than half of the power the car will use during precondition so the car will probably only be 97% charged at the set time. With a preconditioned battery and cabin your range will still be longer than if you did not precondition.

  6. Tack för snabbt svar! Hur ställs temperaturen på varmluften som skall komma inne i bilen in? Är det senast inställda i bilen och bara mot vindrutan(defroster)? Eller full värme överallt i bilen?
    Fråga 2: om man väljer att INTE ta kompfortpaketet(allergisk mot massa knappar i ratten) då har ju bilen manuell AC som standard…funkar föruppvärmning då med?
    offtopic: Är i3 jobbig att köra utan farthållare med tanke på regeneringen när man släpper på gasen? eller kan man lägga i Neutral och rulla o vila gasfoten? Aldrig hört nån som lagt i Neutral o rullar i o för sig../nyfiken 🙂

    1. Hi Thomas,
      1) Preconditioning will always use full heat and against the windshield.
      2) I believe precondition is available on all i3, but please ask your dealer to make sure. An important aspect is that I do not believe that the REX model has a heat pump (there is no room) so the heating uses more power.
      3) The one pedal driving is awesome! You will like it. During the first test drive it takes some time to get used to, but soon you will discover that it is very comfortable. Unfortunately the regen is not as strong as it used to be (software update).

  7. Följer med spänning utvecklingen..väntar på den ankommande med längre räckvidd i sommar! Tack för en jättebra info sida 🙂

  8. Hello, I own an I3 REX and have cabin heating problems. Last Friday I left for a 50km trip here in Germany with a preconditioned car. The temperature in the car was fine throughout the trip. The outside temperature was -2C and it was snowing. After arrival I parked the car in a parkhouse for an hour. German parkings rarely have charging stations. (Germany is a terrible EV backwater…) On the way back home, I started the REX to be able to get back home but I noticed that the heating system, nor the A/C worked. After 20 km, I pulled over, stopped the car 5 minutes to reset the software but still no heating. I called BMW from the car but they had no clue. Later in the evening I read on an American forum that this is a known phenomenon. The next morning I preconditioned the car for a short trip (without REX) and all was well.
    Does anyone have an idea what is the cause and perhaps the cure ?

  9. Hei
    Jeg bruker forvarming av min i3 daglig. Problemet er at det er mye støy forbundet med viften. Jeg måler fra 60-85dB 8-10m fra bilen når det er -2 grader ute.
    Er dette normalt?
    Viftelyden er så høy at jeg har sluttet å bruke forvarming av hensyn til mine naboer.

  10. I am a little uncertain on time.
    If I leave home at 0700, I would set departure In car for 0400?
    It would be nice if BMW had you set 0700, and it determined based on temp when the battery conditioning and cabin conditioning should begin.

    1. Hi Walter,
      You set the departure time (07:00). If it is very cold the car may need to start preheat early and if it is not it will start later. It is optimized.

  11. Jag undrar om man måste ha tillvalsutrustningen ConnectedDrive för att kunna styra förvärmningen via app

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