To Swap or Not to Swap?
Swappable batteries are increasingly touted as a lower emission alternative to embedded batteries, and some companies are already operating swappable systems. As analyses of the costs and benefits of swappables continue, impressive performance gains from a new generation of “extended embedded” batteries indicate that the rush to swappables is premature.
By Paul Steely White
The labor and carbon impact of transporting e-scooters back and forth to a central charging location has bedeviled micromobility from its start. The logistics involved are complicated and costly, and keeping batteries charged in fleets with thousands of vehicles can be a drag on both profitability and sustainability.
The answer, some say, is “swappable batteries,” — scooters designed with quick-release baseboards so that depleted batteries can be replaced with charged ones in the field. Companies taking this approach report that it has helped to reduce carbon and operational costs since only the battery — not the whole scooter — must be transported in order to recharge the vehicle. Though this technology is still new, behind the scenes in the highly competitive scooter world, some companies are pushing for the swappable design to be mandatory and calling for cities to require it in their permits, essentially calling for the forced phase out of embedded batteries.
The benefits of swappable batteries for shared electric scooters are not yet confirmed, and several engineers — including those at Superpedestrian — believe that moving to a swappable mandate will stifle innovation that has recently led to major gains in both the capacity and longevity of embedded battery designs. When the additional efficiencies from distributed charging infrastructure are taken into account, it’s even clearer that limiting the industry to one type of battery or the other is both premature and counterproductive.
“The cost/benefit analyses that many are using to evaluate the value of swappables is flawed,” says Eric Barber, Superpedestrian’s Director of Engineering. “There are definitely reasons swappables are worth exploring, but there are just as many unanswered questions, like, which battery architecture uses the fewest batteries in the long-term?”
Indeed, a swappable model requires companies to manufacture and store approximately 1.5 batteries per vehicle in order to maintain an active fleet. Contrast this with Superpedestrian’s larger “extended embedded” battery that has a longer absolute lifespan, meaning that batteries are designed to be used beyond the useful lifetime of the rest of the scooter. Superpedestrian’s extended embedded battery ensures that less than one battery/vehicle is required for each LINK scooter we manufacture.
Another important issue, according to Barber, is range. Swappable batteries have hinges and locking mechanisms which supplant battery space, reducing the capacity of swappables by up to one third and increasing charging frequency. LINK’s embedded battery has a 55mi+ range, and only requires charging every 4–7 days, depending on usage patterns. This extended range means that riders can travel further, and miles driven for charging pickup and redeployment are minimized. Furthermore, charging pickups coincide with routine maintenance inspections so our mechanics can ensure the mechanical safety of every vehicle at least once/week.
Safety is also a key issue. While all batteries can be designed to prevent problems such as water penetration, swappables are an easier target for battery tampering, and more moving parts are prone to more damage. Swappables are designed to be more easily accessed for removal, but this also makes them easier targets for vandalism and theft. Furthermore, batteries which are routinely swapped may suffer from issues such as wire connections being worn down over time, or enclosure latches failing. Swappable batteries are also at greater risk of being dropped and damaged during handling, which increases safety risks.
Barber reports that his team has been attempting to answer these questions while they continue to research the costs/benefit of a swappable option. At least for now, Barber says, “The jury is still out. We’ve achieved impressive operational and emissions savings with our smart, longer-lasting embedded battery that only needs to be recharged every four days or so. When you pair this long battery life with decentralized charging stations and clean support vehicles, then fixed batteries beat the best swappables on the market right now.”
Barber sums it up thusly: “The swappable model requires more than one battery per scooter. We only need 0.5 batteries per scooter because our batteries last over two LINK scooter lifetimes — about 5,000 trips. The impact of battery manufacturing is far greater than that of maintenance miles driven for charging, so from a sustainability perspective there is currently a clear benefit of embedded over swappable batteries.”