BMW i3: Understanding How Preconditioning Works

Setting the preconditioning feature from the i3's iDrive is simple, but not as intuitive as I believe it could be. You can set the time of departure for every day of the week and the i3 will be charged, preconditioned and ready, provided you're charging from a proper 240v, level 2 electric supply. 

In many ways electric cars are very similar to their internal combustion counterparts and that's by design. Most major OEMs are afraid to make something that's "too different" from what their existing customer base is comfortable with. However there are features in electric vehicles that are indeed drastically different. The first one that comes to mind is regenerative braking which allows the electric motor to convert the vehicle's kinetic energy back into electricity which in turn recharges the battery. This feature changes the driving dynamics of the car (some more than others depending on how aggressive the regenerative braking system is) and the operator needs to adjust to this when they first transition to an electric vehicle.

During the winter months preconditioning in New Jersey not only means getting into a warm car in the morning, but it also adds valuable miles to the car's range by warming the battery cells up to their preferred operating temperature.

Another unique feature most modern electric vehicles have is the ability to precondition (warm or cool) the high voltage traction battery as well as the passenger cabin. This allows the driver to begin their journey with a properly heated or cooled battery and cabin, while still having the state of charge at or near 100%. Some conventional combustion cars also allow you to remotely start the vehicle to warm it up in the winter or cool it off in the summer, but the reasoning behind that is purely comfort-driven, and with EVs it goes beyond that. Since electric vehicles have shorter range and longer refueling times than their combustion counterparts, it's important to save the energy in the battery for its main purpose; to propel the vehicle, and not waste too much of it on ancillary power draws.

Warming the battery and the cabin uses a lot of energy, and doing so while the vehicle is plugged into the main power allows the driver to begin their trip with a properly warmed battery (which will increase the range) and still have a fully charged pack. This is very important for EV owners in cold weather climates. It is also useful to cool the car in hot ambient temperatures, but more frequently used by EV owners in the cold since a cold battery can reduce its range up to 30%. A hot battery won't reduce the car's range, but it can have an adverse effect on the longevity of the battery cells. Therefore preconditioning the battery in very hot climates is also advised, but for different reasons than doing so in the cold.

During the day my i3 is parked outside while I work. Accessing the preconditioning from my iRemote app is very useful as I don't have to go outside to the car to turn it on.

OK, so it's clear preconditioning is useful, but do you really know how it works on your i3? I'm afraid most i3 owners don't. In fact, judging by how many people have messaged me this winter asking for help with preconditioning, I'm thinking it's right up there with how to properly care for their battery as the top misunderstood items of i3 ownership. This is all new stuff, and even most dealers don't know all of the answers so it's no surprise the customers are a bit confused. This post should clear the air on most questions about how preconditioning works on your i3. I knew how most of the i3's preconditioning worked, but just to make sure I didn't have anything confused, I reached out to BMW's top electric vehicle technical services manager in the US to get answers to direct questions that I had previously received from readers:

Q. When Preconditioning via the iRemote app Remote Control menu is activated, only the cabin is preconditioned, not the battery, correct?

A. When triggering Preconditioning from the Remote Control menu, the answer is Yes, only the cabin.

Q. If you want to precondition the battery from the app, you need to set the departure time and then enable �preconditioning for departure," correct? 

A. Yes, provided the departure time programmed is at least 3 hours from the time when it is selected.
*Important: This is a very important fact that most i3 owners are not aware of. If you don't set the departure time at least three hours in advance the car is not performing battery preconditioning at all, only the cabin will be preconditioned.

Q. Can you precondition the battery without the vehicle being plugged in?
A. The HV battery, no. The cabin, yes.

Q. Can you precondition the battery while the vehicle is plugged into a 120v source or does it need to be connected to a 240v source?
A. 120V (Level 1/OUC) or 240V (Level 2) have the same effect in terms of Preconditioning. However, if charging on Level 1, the preconditioning consumption is higher than the charge rate, therefore potentially the vehicle will not be fully charged at the departure time.

Q. How early before the departure time will the vehicle begin to precondition?
A. When using the vehicle preconditioning menu, it will depend on temperature, but generally 30-40 minutes prior to the set departure time the cabin preconditioning will start, and the battery preconditioning will start 150 minutes prior to that.

Q. Will the car ever turn a battery warming on by itself if the battery temperature gets critically low. For example, the car is parked outside and plugged in and the battery temperature drops below 30 degrees, will the preconditioning turn on and warm the battery up without owner intervention?
A. No. User intervention is required for battery preconditioning. If the battery temperature is very low, it will be outside its normal operating temperature. As a result, the power output and usable energy of the battery will be reduced.

Q. How about if it gets critically hot � over 105 degrees?
A. If the battery temperature is higher than the optimal operating range and preconditioning is activated, the battery can be cooled. This is not very common due to the fact that the battery is such a high thermal mass, is located close to the ground, and is not exposed to direct sunlight.

Q. Why is it that sometimes after preconditioning (plugged in) the car is left at 97% or 98% SOC? Why doesn�t it fully recharge the car to 100%?
A. When preconditioning using a Level 1 charger, the car will always be below 100%. It could be about 80% or lower.(Because it uses more energy than the 120v source can provide) When using a Level 2 charger, the SOC could be slightly under 100% as the vehicle electrical load stays somewhat constant while the charger will switch off and on.

Q. Will battery cooling occur automatically while you are driving when the battery temp exceeds a certain set point?

A. Yes.

Q. When battery preconditioning is being performed, what is the battery temperature that the vehicle is attempting to achieve?
A. The battery is warmed or cooled to bring it close to or within the optimal operating range of 25-40C (77-104F)

I'm certain that the vast majority of i3 owners are not aware that the car does not initiate battery preconditioning unless they set the departure time at least three hours in advance. Also, based on feedback I've received here, many i3 owners aren't aware that they aren't preconditioning the battery if they initiate precon by pressing the small fan icon at the bottom of the main state of charge screen on their iRemote app. By doing so, that only initiates cabin warming or cooling. In order to precondition the battery as well as the cabin from the app, you must set a departure time at least three hours in advance and then slide the preconditioning tab to "on." Don't feel bad if you own an i3 and didn't know all this, most client advisers at many BMW dealerships don't know it either. It's a little confusing at first, and honestly I think the app could be made a little more intuitive, but once you understand how it works, it's easy to set. You can also set the departure times and precon from the iDrive in the car.

Using the "Activate Climate Control" app feature on the left only preconditions the cabin. To precondition the battery as well as the cabin, use the "set departure time" feature which is accessed by pressing the small clock tab on the top right of the state of charge display screen. Once you set the departure time, you also need to slide the precondition tab to the "on" position.

Living in northern New Jersey I get to experience a range of temperature extremes and using the preconditioning feature is definitely helpful. We just finished the coldest month I can ever remember and it seemed just about every day I was leaving the house in the morning with temperatures in single digits or below zero. One day it was actually minus eleven degrees Fahrenheit when I began my morning drive. Even though my car is parked inside my garage, when it's this cold the battery temperature drops to levels that severely impact its performance and the range is reduced. I noticed I could add as much as eight to ten miles to my range if I used the preconditioning on the coldest days. It's also nice to get into a warm car, and this enables you to turn down the cabin heat a bit, which additionally helps extend the range. I found that if I allowed the preconditioning to warm the cabin, I could then lower the cabin heat, or even turn it off for a while and just use the heated seats which use much less energy than the cabin heater. 

I hope this helps i3 owners understand a little more about preconditioning. If you have more questions, please leave them below in the comments section and I'll do my best to answer them.

BMW Initiates "Light and Charge" Pilot Program

It seems BMW has been busy developing new ways to charge your i3 or i8 lately. A few months ago I posted information on BMWs new low cost DC Fast charger and I just got word from an i3 owner in California that the first one is already up and will soon be ready for use at Crevier BMW in Santa Ana, California.

A member of the i3 Facebook group posted this picture from Crevier BMW. BMW's new DC fast charge station has just recently been installed there.

The latest news out of Munich is BMW's "Light the Charge" program. BMW has developed LED streetlights that also have built in charging stations. They already have a couple of them in place outside their Munich headquarters, and will soon begin installing them around the city of Munich for a pilot program. The units will be networked and allow the customer to pay with a credit card or by swiping an RFID card from a partner charging network provider. In the US, BMW's charging partner for ChargeNow is ChargePoint.

The European version of BMW's light pole charging station. In Europe, the EV driver carries the cable that plugs into their car as well as the EVSE. Here in the US, the cable is permanently tethered to the EVSE.

The obvious issue with adding charging stations to light poles is available capacity. Will the utilities have to pull new wires to accommodate the added demand or are they already over sized and can handle the additional load? In Europe the standard electrical supply is 230v so there is already more available power than we have here in the US where the basic household supply is 120v. I'd imagine most light poles here are typically 120v, but I'm not 100% certain about that. Pulling new wires and upgrading the lights could prove very costly, more so than even installing stand along charging stations, but I could see how using these on new light pole installations would work.

Charging stations on all these light poles would be great for workplace charging, airports and shopping malls.

Besides street side parking, I could also see how this approach would work well for large parking lots. Instead of having the charging stations all located in one place, which typically is a desirable location close to the buildings, they could be scattered all over the parking area, and each light pole could service the four parking spaces surrounding it.

Whether this idea comes to fruition and becomes a reality beyond the pilot program is unknown at this time, but I like that BMW is really giving thought to how they can improve public charging for their customers. The maturation of the public charging infrastructure is crucial for mass electric vehicle adoption, and I hope BMW continues to explore new ways to help make it ubiquitous.

REx To The Rescue

Those that have followed this blog since before I got my i3 know I toiled a bit over whether to get the range extender option or not. Having lived with pure battery electric vehicles for five years I really didn't like the idea of hauling around an internal combustion engine if I really didn't need to do so, even if it was a very small, efficient one.

Ultimately, the decision was easier than I had hoped. Once it became clear the i3 would have significantly less electric range than the two previous BMW-made electrics that I've been driving (MINI-E and ActiveE) I knew I needed the REx. As much as I love the i3, I'm still disappointed BMW moved backwards with the electric range in every EV they have produced. The MINI-E was good for a reliable 100 miles in moderate temperatures, the ActiveE about 90 miles and the BEV i3 is EPA rated at 81 miles per charge. I drive a lot and 81 miles would just be cutting it too close for me, especially in the winter when the range is negatively effected by the cold weather.

Our Equinox, Tacoma and i3 joined by my old ActiveE before I turned it back in.

So i3 REx it was for me, and fortunately I'm very happy it worked out that way. Without the reassurance of a long range EV like Tesla's offerings, there will indeed be some cases where the limited range of the sub-100 mile EVs require you to alter your plans or make compromises. I accept that because for me the advantages of driving electric far outweigh any small inconveniences that occasionally arise from the limited range or charging times. However the range extender option on the i3 was inciting because I knew I'd be driving on electric for 95% of the time, but still be able to take the car on days that I knew I needed to drive further than the range could accommodate. That has indeed held true because I have a little over 11,000 miles and only about 500 of those miles were with the REx running. However so far the REx was just a convenience, allowing me to take my i3 on days I needed to drive far when I otherwise would have taken one of my gas cars. I hadn't faced a situation where I really needed the extra range, and didn't have any other options, until last weekend.

Plugging the tire

My wife and I have two gas vehicles besides the i3. Meredith drives a Chevy Equinox and I also have a Toyota Tacoma pick up which I use when I need to haul large items like refrigerators for my restaurant, and I also use it to plow my driveway and the parking lot of the shopping plaza that I own and manage. These are our long range cars for trips like when we go to my in-laws in Vermont. So when Meredith needed to go on a company retreat which was 95 miles away in Pennsylvania she naturally planned on taking her Equinox. About a half hour before she was ready to leave, I went out to the garage to give the Equinox a once-over. I always do this when she's going far from home, just to be safe. The first thing I did was a quick visual inspection of the tires and wouldn't you know it, the first tire I looked at had a large screw sticking right into it and in a perfect position for me to see it. OK, there is no time to fix this now so the Equinox is ruled out. No problem, I'll load up her stuff into the Tacoma and she'll use that. It can use a good run anyway since we barely ever drive it. I then remembered that I needed to refill the washer fluid because it was empty the last time I drove it. I popped the hood, filled the fluid and when I closed the hood I heard a loud cracking noise and the hood popped back up. As I lifted the hood I could see the latch that holds it closed was rusted and cracked in half. With no way to secure the hood closed that rules out the Tacoma. There's only one option now, she'll be REx-ing it to the retreat.

The owners of the B&B she stayed were nice enough to let her charge up. They told her their son in law drives a Volt so they weren't totally surprised about a car that needed to plug in.

After a quick REx briefing (I don't think she had ever driven it in REx mode before) she was off. Since the temperature was in the 40's and it was all highway driving, I knew she'd only get about 60-65 miles before the range extender turned on so she'd be driving about 30 miles with it running. I had a full tank of gas so she wouldn't need to stop for gas on the way there, however we didn't know if she could plug in at all once she got there and she may have to drive the whole 95 miles home in charge sustaining mode. I've driven the car enough to know this wouldn't be a problem as long as she kept her speed under 75mph, other than the fact that she'd have to stop for gas twice on the way home. I did a quick check to see if by chance there were any level 2 charging stations near where she was going , but as I expected, there were none. Luckily, the bed and breakfast she stayed at allowed her to plug into an outlet they had on the garage, so she was able to charge at 120v overnight. Since the retreat lasted for four days, she had no problem fully charging even with using the car to run some local errands every day.

So even though I've used the REx a dozen or so times already, this was the first time it was absolutely necessary, and further validates my decision to shell out the additional $3,850 for it. It really makes the car so much more versatile, and allows me to not even think about the range. As others have noted, it really does allow you to drive more electric miles because you can use it for trips you otherwise couldn't with the BEV i3. Obviously, the ultimate goal is for longer range electric vehicles to become more affordable, and infrastructure to mature to the point where public charging and DC fast charge is ubiquitous. However until then, the range extender will play an important role in the adoption of electric vehicles, as it allows for utility that is simply unavailable in the vast majority of today's electric vehicles. 

Trip stats: I was very happy to see 3.7 miles per kWh considering it was about 70% highway driving, with the cabin heat on the entire time.

Stats from the trip:

Going to PA: 61 miles on battery, 34 miles on REx
While there: 49 miles all on battery
Coming home: 65 miles on battery, 30 miles on REx.
Total: 239 miles; 175 miles on battery, 64 miles using range extender
Total gas used: 1.7 gallons (.9 gal refill when she was in PA & .8 gal refill when she was 1.5 miles from home). Averaged 37.65mpg while REx was running.