- A team recently tore down BYD’s latest blade battery pack.
- It took 8 hours plus a deep freeze cycle to dismantle the pack, partly due to the use of structural adhesives.
- They also raise concerns of repairability and recycling.
One of the largest selling points of an EV is the total cost of ownership. Sure, an EV may have a heavy upfront cost and sharp depreciation, but fewer moving parts generally mean less maintenance. That said, serviceability is still a major concern, especially when something as expensive as the battery pack is the point of focus.
Recently, a team of researchers tore down one of BYD’s cutting-edge Blade batteries. What they found is that 1,261-pound pack took a significant amount of time and effort to disassemble—that meant grinding, cutting, hammering, and even freezing the pack in order to tear it down to a serviceable state.
Photo by: BYD
The new Blade battery itself is a genuinely clever design. BYD uses long, narrow cells as structural elements with tight packing. This allows the automaker to achieve greater efficiency and pack density, which is a challenge in itself, let alone in a pack capable of megawatt charging speeds. The compact packaging solution is super useful on the surface, but like all complicated engineering projects, eventually someone has to decide where the trade-offs are. For this pack, it appears that might be serviceability.
BYD, like many automakers, treat its battery packs like giant integrated systems. Cells—all 170 of them inside of the Blade pack—become modules, modules become structural components, and structural components become part oft he vehicle itself. Other manufacturers are pursuing similar ideas today for good reasons (weight savings, rigidity, reducing manufacturing complexity), all of which help to squeeze every last mile out of an EV.
The trade-off is when something goes wrong.
One of the big hurdles during the 8-hour deconstruction was the amount of structural adhesive used to assemble the pack. These adhesives (as the name might suggest) are used to secure components together. They create super strong bonds within the pack that help the contents withstand various environmental conditions, as well as adds to a pack’s overall crashworthiness. It’s also a way to bond the pack together in lieu of fasteners or other weight-adding components. The flip-side is that adhesives can also make the pack difficult to service, which was a rather big point that Sandy Munro made a few years ago when Tesla filled its structural packs with pink foam.
In BYD’s case, the tear down reportedly found these structural adhesives bonded around battery modules, busbars, tabs, and even wiring. The team even froze the pack in cold storage for 40 hours in an attempt to make it more brittle for disassembly, but that wasn’t enough to make it easy.
Imagine trying to repair a battery pack like this after a crash, or attempting to revive a single dead cell in a pack as an independent repair shop. You can quickly see how the complexity can equate expensive labor that makes repairing a pack very costly, or how insurance rates can skyrocket if a battery can only be replaced. (Although when most existing EVs get crashed, the entire pack gets replaced, with refurbishment happening off-site before the pack is potentially resold.)
Car News China says that the team declared the BYD pack as the hardest one they’ve disassembled yet, and they’ve done this with more than 20 different packs so far. They made it a point to call out the broader challenges that integrated EV battery pack structures create for EV repairability (especially since they couldn’t safely use heat or chemicals to remove the adhesive), as well as potential challenges for recycling at the end of a battery’s usable lifespan.
This may become one of the more interesting EV debates over the next few years. Consumers want longer range and cheaper cars, which means automakers need manufacturing to be cheaper. The industry could very well push for techniques like more efficient packaging, lower cost, and denser batteries to achieve those goals.
The difficult part that seems to be left out of the equation is when someone actually needs to fix these things. Because eventually—whether it be after an accident or just a car beyond its warranty period with a bad module—there will be a need to service batteries.