Electric Bikes can be lightweight
Is a lightweight bike possible? Coboc made a 24lb ebike and others can make even lighter ebikes.
Heavy bulky batteries: The biggest drawback to eBikes to date but advancements in technology could change this.
The average battery back on an eBike to date is around 12 pounds with larger packs weighing much more. As manufacturers push for bigger batteries for more range the bikes get heavier and heavier.
But do we really need the range?
Let’s look at the question like a daily commuter would. The average urban commuter drives 30 minutes to work with traffic only going as little as 10 miles or less. So it’s a no-brainer to use alternative mobile transportation when you can. This is one of the many areas eBikes have become increasingly popular.
The size of the battery you would need to make this commute to work and back depends on how much energy you demand from the motor but ultimately its the battery size that makes the biggest difference. To understand how much battery you would need for this commute we need to understand battery math!
Volts and Amp hours, every battery pack has different specs. For example, a 20ah 48volt battery holds about 1000 watt-hours of energy and weighs around 12 pounds. This same battery 10 years ago would have been much much heavier requiring more space.
- Voltage: Most eBikes run either a 36v or 48v system with some as high as 52v. The higher the voltage from the battery the more power the battery can deliver. For example, the higher the voltage an electric motor can take the more powerful the motor will be in torque and max speed. That’s why most eBikes run a 36v or 48v system which is more than enough for a 350watt or even a 750 watt motor.
- Amp Hours: The amp hour rating is how much energy capacity is in the battery. But the true energy capacity you also need to consider voltage. Remember that higher voltage components have more power but demand more power thus draining the battery faster. The more amp hours you have the longer it takes to drain the battery. Finding that sweet spot between amp hours and volts is where the key to battery weight is.
Heres a few combinations of batteries and motors with range estimates:
- 36v 10ah battery + 250 watt motor = est 65 miles
- 36v 10ah battery + 350 watt motor = est 50 miles of range
- 48v 10ah battery + 500 watt motor = est 30 miles of range
- 52v 10ah battery + 750 watt motor = est 15 miles of range
As you can see the more power you demand the more amp hours you will need.
The answer to how much range we really need:
There is no real way to know exactly how much range you will need, every rider rides for a different use for an ebike. But if we just use our daily commuter as an example to go 10-15 miles, we can easily achieve this with a smaller battery pack and a smaller motor thus greatly saving weight.
But what if you do not want to sacrifice power and performance because of weight?
The answer could be in modular single cell packs. When Apple computers designed the macbook air they were challenged with cramming in as much battery to a thin lightweight case as possible. In order to keep the dimensions of the ultrabook thin and light they completely needed to rethink how batteries were made and used.
Dividing the battery in separate packs and inner connecting them all allowed Apple to place the battery in multiple areas spread across the frame, without increasing weight. So image a bike frame with packs not battery cells and the packs are located inside parts of the frame of the bike.
Doing this has many weight benefits but also weight distribution.
In the end, there’s always a difference from what we really need vs what we want. Electric bikes are fun, really fun that’s why you see newer ebikes just getting faster and more powerful. But if you strip that all away and you’re just looking for an efficiant ebike that still gives you the boost you need without breaking a sweat it can be done, and done very well.
New tech like doped bikes in Europe are already under 15 pounds bu removing traditional motors completely.
more info can be found on this blog here.