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.
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.
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.
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).
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.