Increased Battery Efficiency: What's the Forecast?

Jack Tyler

Active Member
As some of you know, I'm an ebike novice and using this Community site to build knowledge before purchasing an ebike for use in a small Montana city an hour north of Yellowstone. But one fundamental aspect of ebike performance crosses over into my flying avocation and that's battery efficiency. Being a pretty tech savvy group, most of you will already know that electrically powered aircraft are already being produced, sold and used in pilot training. And there is a LOT of development work being done right now on hybrid and electric-only aircraft designs, with a number of these designs in prototype form and being flown. Even Air Bus has decided to enter this arena in a big way, building a $55M USD factory with the expectation - eventually, perhaps three decades down the road - of building a regional commercial carrier that's hybrid powered.

I mention this because it's now somewhat common to see discussions about energy density improvements in battery systems when reading about aviation. (Who would have expected this only ten years ago...?!) And of course here we see constant comments about the expectation (or is it more 'hope'?) about significant ebike battery efficiency gains. So I thought this short interview with Jeff Chamberlain of the Argonne National Labs in Illinois might be of interest. The bottom line: Near term improvements in Lithium Ion energy density is likely to be ~7% per year. Longer term, there are some reasons to hope for more significant improvements...but don't look for twice the battery capacity in half the space any time soon. (For more about electric propulsion trends in aviation, here's a readable update with mention of Air Bus' plans. Or go here to read a bit about a hybrid aircraft power plant currently being tested.)

Some of you will have much more info on this topic. Feel free to share it and we can see how it aligns with Argonne Labs' assessment.



Jack Tyler, the 7% number sounds right. Elon Musk said the batteries will improve at 5% a year, when he introduced the P90 kilowatt upgrade over the P85 killowatt battery. In Elon's opinion a 15% upgrade is "worth it" as far as difference in improving a vehicle. At a later occasion, Elon quoted 6% upgrade per year(sounded like the worlds improvement rate is it's self increasing). At 7% a year you could get a meaningful upgrade in 2 years instead of 3 years. Amazing how quiet an electric plane is in the video you reference.