It’s the time of year when the leaves start turning color, when Sundays mean most televisions in the US are tuned to football games and the Holidays are just around the corner. However something even more grim than the best Halloween costume is also making its return: Reduced range for EV owners.
I think back six years ago to my first year in the MINI-E program. It was 2009 and there weren’t many electric vehicles on the roads, especially outside of Southern California. About five months into the MINI-E Trial Lease program there was suddenly a rush of owners bringing the cars to their MINI dealer for service, telling them something was wrong with their cars. This occurred in late October…
Suddenly, the cars couldn’t go as far as we were used to, and the range drop off seemed to happen very quickly, without notice and without reason, leaving many people to assume their car was malfunctioning, and perhaps had a bad battery. Some of the people even swore the range drop coincided with their last service visit, so there had to be something done at the dealership that caused the loss of range. I had read quite a bit about electric cars before getting mine, and knew there would be some range degradation in the cold winter months of Northern New Jersey, but I really didn’t know how much the range would drop. Evidently many of the other participants were completely in the dark about what to expect once the winter months arrived. Some were so put off by the range degradation, they insisted that BMW take the car back and allow them to leave the program. I remember one particular person tell me that drop in range meant they could no longer make the round trip to work every day, so the car was of no use to him for three months of the year.
When the MINI-E program ended in 2012 I joined the BMW ActiveE lease program. By then some of the participants were aware of the effects the cold weather has on EV batteries since mainstream EVs like the Nissan LEAF and Chevy Volt had both been available for over a year. However there were still quite a few ActiveE drivers who were caught off guard by the loss of range once winter rolled around, and this became a major topic of discussion among the ActiveE discussion forums. Just as with the MINI-E drivers, many believed their car was experiencing some kind of battery problem, and couldn’t believe the range would be affected so much by the cold weather.
This issue affects all electric cars, even those with sophisticated thermal management systems. Tesla for instance, like the i3 has a state of the art thermal management system, and the Model S is just as susceptible to cold weather range degradation as any other EV. The good news for Model S owners is that the range is so great, you usually don’t miss the miles you lose in the cold. However there are times you do. Last fall I had a Model S pull into the parking lot of my restaurant, the owners plugged in, came in and sat down to eat. As I usually do when an EV owner comes in, I went over to their table, welcomed them and asked about their car. They told me they were new owners, and traveling from Upstate New York State to South Jersey. They had planned to stop at the Edison Superchargers but realized they wouldn’t make it without stopping to charge. They said they were getting 250 miles per charge in the summer, but on this trip, which was all highway and temperatures were in the 30s they were only getting 185 – 200 miles on a charge. The cold effects us all…
Not Much Progress With Education
So here we are in 2015 and not much has changed. The US i3 launch was a year and a half ago and for many owners they are about to witness for the first time how the cold will reduce their range. I am the admin in the i3 discussion forum over at mybmwi3.com and the reduction of range in the cold is a frequently discussed topic. Just as with the MINI-E and ActiveE programs, there are people who are convinced that there is something wrong with their car. There’s always the possibility there could be a problem with a particular vehicle, so I would recommend anyone concerned to take their car in for service to have it checked out. However I’m sure most everybody is going to get a clean bill of health, and at that point they are going to have to come to grips that the reduced range is due to the temperature, and learn how to live with it.
I will say I believe BMW (and most other OEMs) aren’t doing an adequate job of offering educational information for new owners. It wouldn’t have been too difficult or expensive to prepare an information card which would help new owners understand how temperatures can affect their range. I’ve had many i3 owners reach out to for information about this, many concerned they have a problem with the car. I think BMW should make a “Battery 101” information card and hand it out to all new owners at the time of delivery with their other vehicle documents. This could cover temperature issues as well as tips to help extend the life of their battery, offer advice for long term vehicle storage and offer a brief explanation on how the battery system works. I believe owners would appreciate this kind of information. It feels a little like Groundhogs Day with the same questions about range coming up every winter. There has to be a better way to prepare the customers before it becomes a problem. BMW has the educational information available, and they have posted it (see charts below) on the BMW i Circuit Forum. However, I believe this information should be included with the car, and explained to the customer along with all other pre-delivery documents.
That said, there are techniques which can help offset the effects the cold weather has on the battery and improve your range. Here are some of my recommendations to help get you through the cold winter months:
Precondition: Use the precondition function as much as possible. The i3 will preheat the battery and passenger cabin off grid power, so you don’t drain the battery performing these functions. By doing so, you will use less of the stored energy in the battery, which will allow that energy to be used for its main purpose, to propel the vehicle. You can set the preconditioning to begin every day at a set time so your car is ready for you when you leave in the morning. Make sure the car is plugged in to a Level 2 (240v) charging source while you precondition because a Level 1 (120v) EVSE cannot provide enough power for preconditioning. If you use the 120v Occasional Use Cable that came with the car, you won’t be 100% charged when you leave, as the preconditioning function uses more energy than the OUC can supply. To precondition properly, you need a 240V Level 2 EVSE.
*Read my detailed post on preconditioning the i3: Understanding How Preconditioning Works
Cabin heat: Limit the use of the cabin heater as much as possible. The BEV i3s are equipped with an advanced heat pump which is much more efficient than the resistance heater used for the REx i3s. However it still can use a fair amount of energy and will indeed cut into the range. If your i3 is equipped with heated seats I highly recommend using them as much as possible. By doing so you can use the cabin heater less which saves energy since the heated seats use much less energy than cabin heater; heat pump or not. If you simply dress a little warmer and use the heated seats you can really cut down on the use of the cabin heat, and this will definitely have a positive effect on your range. If you are wondering why i3s with the range extender do not have a heat pump, there are two main reasons. First and most importantly, the actual heat pump on the BEV i3 is located where the gasoline tank is on the i3 REx, so there isn’t room for it. Secondly, squeezing every mile possible out of the battery isn’t quite as important with the REx i3, since you can still continue driving once you exhaust your battery. With the BEV i3, those extra 3 or 4 miles the heat pump may add might make the difference in you getting home or not on a cold night.
Properly inflated tires: Tire pressure falls as weather turns colder. Some tire experts say that for every 10 degrees of temperature drop your tires can lose 1-2 lbs of pressure. Under-inflated tires create more road friction which will reduce efficiency. Some EV drivers I know actually add four to five pounds of pressure to all of their tires before the winter months begin. Always make sure to check the recommended and maximum pressure for your tires, as proper tire pressure is different for every tire and car.
Park inside: Whenever possible park the car in garages, especially if they are heated. If you park outside for an extended period like while you work, you should find a spot that will be in direct sunlight for as much as possible. By parking in direct sunlight you’ll have a warmer cabin and battery when you return to your car later.
Slow down: Besides preconditioning and conservative use of the cabin heater, driving a little slower is perhaps the best way to extend your range. This is true regardless of the ambient temperature, but during the winter months driving a little slower can help offset the range you lose to the cold. If you do knock off a few miles per hour on the highway, make sure to move over into the right lane so you don’t hold up traffic. Also, try to accelerate slowly form a standstill. Jack-rabbit launches are definitely fun with the i3 but they do consume a lot of energy.
Charging times increase: While you’re charging, the thermal management system will also be working to warm the batteries. This takes some of the energy that would have gone directly into the battery and uses it for the thermal management system. On really cold days I’ve noticed it takes my car 30 to 45 minutes longer to fully charge. Knowing this you may have to adjust the delayed charging setting on the car and allow for more time before you can unplug.
Use Eco Pro Modes: The i3 has two Eco driving modes to complement the default “Comfort” driving mode; Eco Pro and Eco Pro+. Both modes reduce power supplied to the motor and energy consuming features like the cabin heater. Most features work fine in Eco Pro mode, but Eco Pro+ restricts the power so much to them that some no longer even function. Another benefit to using Eco Pro and Eco Pro+ in the winter is by reducing the power to the motor the car accelerates slower and helps to reduce the possibility of wheel spin. I definitely recommend using Eco Pro mode whenever driving on ice or snow covered roads, it definitely improves traction.
Below is an interesting chart prepared by FleetCarma. It compares the effects of the cold on the fuel efficiency of an electric car and a gasoline car. It isn’t i3-specific and not exactly what I’m discussing here today, but it helps to see how both gas cars as well as electric vehicles are effected by the cold. It’s interesting to see that the cold affects the EV more, but the actually energy cost of the reduced efficiency is less on the EV. So while it may be a greater inconvenience for the electric car driver, the cold weather inefficiencies actually costs the gasoline car driver more money.