OPINION: The Sustainability of E-bike Batteries

Words: Daisy Day

Photo: Gerard Lagana

E-bikes. Love them or be full-blown indifferent towards them, they are here to stay. I have been seeing the number of eMTBs on my local trails steadily rising, and it goes without saying that the number of e-bike batteries is also rising. The debate over how “sustainable” e-bikes are, is largely centred around the lifecycle of the battery, though I may have to do a 3-part article on this topic, because there are SO MANY variables to consider in making the most sustainable choice when buying an e-bike. 

However, let’s start on the simple steps that we are most in control of – the considerations involved when buying, looking after, and disposing of batteries. Because at the end of the day, caring for the battery so it lasts a long time means we don’t have to buy more things! 

So here are 3 things we can do to close the loop of the (quite intensive) resource extraction required to make your average Lithium-ion (li-ion) battery.

1. 
   

   Buy Quality

It is important that when purchasing an e-bike, that you consider quality. One study from the Journal of Cleaner Production, highlights that,“internal battery efficiency” is a very important parameter for measuring how sustainable a battery really is. As a general rule. the more efficiently something works, the longer it will last. They looked at factors such as the production of binders, production of lithium salts, cell manufacturing and assembly, and the relationship between the weight of the bike vs. the projected energy consumption required to keep it moving.

Good quality batteries should last between 3 and 5 years if they are well maintained, though you should also note, a lithium battery will slowly lose its capacity over time, even if it’s not used.

2. 
   

   Be a Good Carer

So how does one, as the battery care-giver, prolong battery life? Each battery system has unique needs in terms of charging speed, depth of discharge, loading and exposure to adverse temperatures. As an example, operating a battery at elevated temperatures improves performance, but prolonged exposure to higher temps will shorten its life. On the other hand, really cold temperatures reduce the available mileage of your battery, and charging your battery in below freezing temps can also harm the cells. Much like us, batteries are a wee bit fickle with their happy temperature range.

In my opinion, the takeaway here is simply to not leave your bike/battery in a hot car for hours at a time. Because this is, out of everything, the most common variable we’ve looked at. As a general rule, a battery that is 100% charged will have a “recoverable capacity” (i.e. the usable/ available energy output of a battery) of 94% at 0°C, 80% at 25°C, and 65% at 40°C, and so on. E-bikes die in hot cars.

3. 
   

   Recycling your Battery

When your battery really does die (and because you’ve cared for it so well, this is in 5 years’ time), the MOST important thing you can do is recycle it correctly. This involves recycling within your country – or even better, your state – at a facility that recycles using a hydrometallurgy process. The hydrometallurgy recycling process can achieve up to 95% recovery rate of pure metals. The idea being that these materials will once again be used to make new cathodes that go into new battery cells, reducing the need for more mined metals. I am curious to know how many times over this recycling can occur – I’m assuming endlessly – I’ll get back to you on this!

What I would like to see is for Australia to follow along the lines of the European Union, who enforce the collection, recycling, treatment, and disposal of batteries under what is known as the “Directive 2006/66/EC”, aka, the battery directive. Under this directive, brands that manufacture e-bike batteries must ensure that the batteries they put on market are recycled correctly at the end of their life. This puts some of the onus back onto brands to fully see out sustainable battery life-cycles. This also helps customers put their money where their ethics are – creating an impetus for more brands to jump on board with sustainable battery lifecycle management

There is still relatively limited data in what is, in the scheme of things, quite a new(ish) area of research. The way we make and recycle batteries is changing quite rapidly now that global sustainability goals are at the forefront of (I hope) everyone’s minds – whether they are designing, manufacturing, or buying products. E-bikes are no different. I hope that the same research and development goes into battery life-cycles as it does into improving their performance, weight, and price-point.