Published on March 17th, 2015 | by Christopher DeMorro80
Lighter Batteries May Prove The Tipping Point For Electric Vehicles
March 17th, 2015 by Christopher DeMorro
For battery electric vehicles to overcome the built-in advantages of vehicles rocking conventional internal combustion engines, many analysts point to battery costs as being the determining factor. But an article written for Seeking Alpha emphasizes that there may be another tipping point in the battery electric vehicles vs. internal combustion engines battle, and that’s the weight of the batteries themselves.
To be sure, the main goal of the Tesla Gigafactory is to bring battery costs down by some 30%, allowing the Tesla Model III the ability to offer a 200-mile driving range for just $35,000. Elon Musk has again and again targeted the BMW 3-Series as the Model III’s main competitor, and with a curb weight of just over 3,400 pounds (1,542 kgs), the Bimmer represents an excellent “goal” weight for the average family sedan. The Tesla Model S, with its 4,600 pound (2,086 kgs) curb weight, is a much heavier car in comparison, with about 1,600 of those pounds dedicated to the battery alone. In order to bring the batteries weight down Tesla must bring the watt-hours per kilogram (Wh/kg) up, and it will do that with new battery cell technology.
Currently, Tesla uses thousands of individual Panasonic 18650 laptop battery cells in its battery packs, which cost an estimated $250/kwh and offer an estimated energy density of 233 Wh/kg. Once Gigafactory production begins though, Tesla will be upgrading to new 20700 battery cells, which will be physically larger, capable of holding more energy, and thus requiring fewer individual modules. As battery chemistries and energy densities improve, battery electric vehicles could actually end up weighing substantially less than traditional internal combustion engine vehicles.
According to the above chart, once battery pack density hits about 333 Wh/kg, the Tesla Model III could be on par, weight-wise, with the BMW 3-Series. And what about when the batteries grow even more energy-dense? Electric cars could actually undercut the weight of conventional vehicles — though that assumes conventional vehicles don’t utilize their own weight-saving measures (which they almost certainly will).
Obviously there’s a lot that still needs to happen for electric cars to even be on par with their conventional counterparts, but it’s certainly doable as batteries continue to come down in weight and cost. The BMW i3 manages more than 80 miles of driving per charge, but weighs in at just over 2,800 to 3,000 pounds (1,270 to 1,360 kgs) thanks to its expensive-but-lightweight carbon-fibre body. Now imagine if its 20 kWh battery pack was 50% lighter, and suddenly you’ve got an electric vehicle that weighs no more than the 2016 Mazda Miata.
And should Tesla hit its goal of batteries that cost just $100/kWh? It’ll be even cheaper than the Miata too.