Are Capacitors The Future Of E-bikes?

Ofer Canfi

New Member
I want to start with batteries, scratch that, let's start with laptops and smartphones; without them there will be no electric bikes as we know them!

The advancements over the last decade in battery technology is intertwined with the need for smaller more potent power packs for our phones and laptops, we want bigger brighter screens, longer work time and faster charging. All given to us with the proliferation of Lithium based batteries.

As the knowledge of these batteries advanced both in design and manufacturing technologies, the price went down and they started to appear in more and more products; anything from power tools to LED lights. One field in which the advancement was rather quiet is electric bicycles; since up until five years ago 95% of the E-bikes produced globally stayed in the east, the west was left behind and only today is starting to catch up.

But batteries do not come without their own set of problems:

  • The price for a Li-Ion / Li-Poly is still very high compared to other power sources

  • The average lifespan of Lithium based power packs is less than 1000 recharge cycles

  • Charging Lithium batteries is a tricky and sometimes dangerous business

  • Recycling batteries of any type is hard dirty and expensive

  • Materials used to create these batteries are scarce and found in geographically challenging locations

  • Imagine what would happen to this industry if all the commuter we want would really switch to electric bicycles, motorcycles and cars.
So where do capacitors come in? well in comparison capacitors are better exactly where batteries fail:

  • The price of producing capacitors is lower than that of batteries

  • A standard capacitor has between 500,000 and 1 million charge cycles

  • Charging capacitors is easy and very very fast! Seconds instead of hours, allowing regenerative braking to actually be efficient

  • Recycling capacitors is easy and clean

  • The main material used for producing capacitors is graphite, granted that is the same as batteries, but the need for clean graphite for the battery industry has pushed the research in this field and produced amazing results. (PDF here)
The problem lays with the power density of capacitors in comparison to advanced batteries, and although research into graphene and ultracapacitorsis on going, there is no market ready solution yet. (PDF here)

So what do we do? well one option is to just wait...

Wait for the global powers to squeeze all they can from their investments in the battery industry as we waited for them to be done with oil, or at least until new opportunities presented themselves, i.e. fracking or solar power.

My sad conclusion is this, there will be no capacitor based electric bikes in the near future, since there are no capacitors with high power density that are mass produced yet.

It would be like asking for a Lithium powered bike in 1990, it may be possible but ridiculously expensive.

Nor will the companies be developing these any time soon, imagine you bought a good electric bike and it lasted for 20 years; no business in their right mind would do such a thing, not in the current economical climate and the constant need for growth.

Another option is to start our own research and do what tinkerers do best, improvise!

Graphene tech has been reduced to a few dollars per watt from 100K per watt with one single idea. The age of knowledge is upon us and we better make use of it, we can find, learn and build almost anything by ourselves, so I guess if we want to see change we better be the change!
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