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Tuesday, June 11, 2013

When 94 no longer means 94

When I first got the car I could achieve 100 miles per charge if I drove efficiently. However those days are gone unless I drive very slowly and accelerate gingerly. No thanks, I'll live with the lower range!   :)

The range of an electric vehicle is impossible to explain in a single number. The EPA range rating is the simplest way to offer the public an estimate of what to expect form the car and also so it can be compared to other electric vehicles.

However as I have tried to explain in past blog posts, range is a moving target. There are so many factors that can influence how far the car can go like speed, driving style, ambient temperature, topography of your route and many others that's it becomes difficult to really explain to someone how far the car can go on a charge. And that's problematic. It's usually one of the first things people ask me when we talk about the ActiveE. While I want to be as descriptive as possible, I also realize I can't spend to long harping on how different conditions can influence the range because that scares people. Well now I'm going to make it even more scary.

Up until now I have only focused on the outside influences that can effect range; now I'm going to talk a bit about the car itself. I've had the ActiveE for about 17 months now, I'm closing in on 50,000 miles and I've recharged it 1,125 times. In other words, it's no "Spring chicken" anymore, and the battery is showing signs of reduced capacity which means reduced range. For example, in the month of May in 2012, I averaged 96.51 miles per charge, but in May of 2013 I averaged only 83.19 miles per charge. However it wouldn't be fair to only only look at the average range. My consumption rate(my personal driving efficiency or how many miles I drive per kWh's used) was much lower in 2013 so I was driving less efficiently which would account for some of the drop in range by itself. In May of 2012 I had a 3.53 mi/kWh rate and in May of 2013 it was down to 3.27; no doubt due to my late night, highway driving at higher speeds. Still, if I adjust the consumption rate based on the current available battery capacity I would have averaged 89.4 miles per charge instead of the 83.19 that I averaged, which is still a 7% loss of range from May of 2012.

A 7% annual loss of range would be very bad, but you must remember I'm not the average driver. From May 1st, 2012 to May 1st, 2013 I put 35,229 miles on the car and recharged it 822 times. That's probably about equivalent to what an average driver would need two years to do, if not longer. My car lost 7% of its range in that time, which is in line with what industry experts estimate, an approximately 3% annual loss of battery capacity. So actually the EPA rating is simply a snapshot of the approximate range expected when the car in brand new. The car is only new once, and the battery pack immediately begins to degrade, albeit at a very slow rate that isn't even measurable for many months unless you had sophisticated instruments that could measure capacity.

So if you lose about 3% of your battery capacity annually, how long before you need to replace the battery? That will depend on your personal driving needs. Lets say your EV have a 94 mile EPA rating like the ActiveE. If you lose 3% of the range annually your "average" range may look something like this:

Year 1:  94 Miles per charge
Year 2:  91
Year 3:  88
Year 4:  86
Year 5:  83
Year 6:  80
Year 7:  77
Year 8:  74
Year 9:  72
Year 10: 69

At what point does the car fail to function as acceptable transportation for you? One thing for sure that will help immensely is if you can arrange to have charging available at your place of work. Personally I believe the auto manufacturers would be wise to partner with large corporations and help them offset the cost of installing charging stations at their campuses. Having the ability to plug in at work will allow many people that wouldn't otherwise consider an EV do so. Plus it would alleviate any concern that the people may have that in three or four years their EV may no longer be capable of the round trip to work. Of course increasing the amount of other public charge points will be helpful also, but workplace charging is by far the most important place to plug in after ones home. I believe manufactures should provide prospective buyers a guideline like above, perhaps it could even be custom tailored to the customers driving demands, climate they live in and consider other factors that effect range also. This would help the customer understand what to expect from the car.

Remember the above figures are only to be viewed as a basic guideline. There are many other factors to consider like how well you care for your pack, where you live, plus there are different battery chemistries used in EV's and some will fare better in the long term than others. Will large format li-ion cells that BMW(and just about all other major EV manufacturers) uses outlast the small cylindrical laptop-type batteries used by Tesla? I'm not sure anyone really knows that answer yet. I do know a lot has to do with how well the thermal management system maintains the proper temperature of the pack, since excessive heat is really the biggest enemy to long battery life.  Many people say leasing an EV is a smart decision now because there are still so may unknown factors that could negatively influence the future value of an EV and NADA resale values of used EV's tend to confirm that. I'm typically not a supporter of car leasing, but in this case I think it may be a smart decision if you can get a decent lease deal on the EV of your choice. I hope BMW comes out with a strong lease offer on the i3, and really believe the lease offer may hold the key to whether or not they hit their targeted sales goal. For people interested in purchasing an i3 a strong warranty that covers not only manufacturing defects but also battery capacity is also essential. I've written before that I feel a 5 year, 75,000 mile battery capacity warranty that guarantees at least 70% capacity would help ease concerns that the car will not rapidly lose its range and leave the customer with a vehicle that can no longer deliver the range needed for daily use.

I don't want readers to get the impression I'm not still optimistic about the adoption of electric vehicles, because I certainly am. I am completely convinced that plug in electric vehicles are here to stay and that we will only see more and more of them every year. However that doesn't mean there isn't along way to go in educating the public about what to expect from an EV and until the education improves, EV's will continue to be fringe, niche cars. In fact, I believe one of the reasons many people aren't considering one now is because they know so little about them so they are a bit afraid of them. That plus the fact that there really isn't a great crop of plug in offering. There are some good EV's out there like the Model S, the Volt and the LEAF, but very little otherwise. Once more manufacturers like BMW get in the EV game and more compelling plug in models are brought to market, interest in these cars will certainly increase. However interest alone isn't enough. Offering solid warranties, attractive lease deals and having thorough information available about what to expect from the car over its lifetime is key to selling them. Many people are genuinely interested and I talk to them every day,  but they need that final push to be convinced they aren't making a mistake.