Potted E-Bike Batteries Are Catching On

With the way lithium-ion battery fires have received media attention, a number of manufacturers have taken steps to bolster consumer confidence that their products are safe for charging and storing in the home. So far, every lithium-ion battery fire we’ve been able to track was caused by an e-scooter, e-moped or other e-mobility device—not an e-bike, but that hasn’t prevented e-bikes to be blamed for these fires.

Manufacturers are taking a variety of steps to reassure consumers that their products are safe. We’ve seen how most manufacturers have sought certification from Underwriter Laboratories (2849 and/or 2271) or the European standard EN15194. Some manufacturers have begun to take additional steps and a technology that is starting to catch on is the practice of encasing the cells that make up a battery with a heat-absorbing resin. These batteries are called “potted.”

When a battery is potted, the cells are assembled in the configuration within the battery housing. The collection of cells is then placed in a mold and the resin, in a hot, liquified form, is poured between the cells. When the resin cools, it hardens, insulating the cells.

The resin insulates the cells in multiple ways. First, the resin can absorb and dissipate heat, so if one cell begins to overheat, the resin can prevent it from becoming hot enough to reach thermal runaway—the point at which a cell is hot enough that a chemical reaction within the cell becomes self-sustaining. The resin also insulates the cells from contamination and corrosion. The salt air of coastal regions can cause corrosion. And should water, whether salt or fresh, penetrate the battery casing, it won’t be able to reach the cells. Finally, potting a battery provides a degree of impact protection in case someone falls, drops the battery or it is struck by something.

We’ve already seen Rad Power Bikes introduce their new Safe Shield batteries. We expect that as they continue to release new versions of their existing models they will update them with their Safe Shield batteries.

Pedego recently announced three new models which will be spec’d with potted batteries.

Other companies not as well known, including Luna Cycles and Grin Technologies were early adopters of potting.