Six real battery packs, torn apart and priced
A research team from Imperial College London, the Faraday Institution and the London School of Economics bought 6 real electric car battery packs and paid to have each one professionally torn apart, tracking the cost of every step. The packs came from 5 different carmakers, Renault, Nissan, Tesla, Peugeot, BAIC and BYD. Inside most packs sit modules, bundles of individual battery cells grouped together, and inside a module sit the cells themselves, the parts that actually store the energy. How those pieces are held together, by screw, weld, tape or glue, decided how much each pack cost to take apart afterward.
The BYD Han pack shows 0 because its cells wire straight into the pack with no module stage at all, not because the number is missing.
Show the numbers
| BYD Han | 0 |
| BAIC BJEV EU5 | 5 |
| Tesla Model 3 | 4 |
| Renault Zoe | 12 |
| Peugeot 208 | 18 |
| Nissan Leaf | 24 |
The 2 cheapest packs skipped the hard parts
The battery pack in the BYD Han has no modules at all. Its cells wire straight into the pack, a design the researchers call a direct pack to cell hierarchy. That single choice made the BYD pack the joint cheapest of the 6 to take fully apart, at 47.41 dollars, even though its individual cells are heavily welded and the slowest single stage to separate, 114 minutes. The pack in the BAIC BJEV EU5 holds its cells together with tape instead of a strong structural glue, which researchers say avoids the sticking problem that glue causes elsewhere and makes the cells faster to pull apart. With only 5 modules, the fewest of the 6 apart from BYD, the BAIC pack tied BYD as cheapest overall, at 50.45 dollars.
Tesla saved money at 1 stage, then hit a wall
The pack in the Tesla Model 3 gathers all its wiring into 1 assembly at one end, instead of spreading it out, which dropped its cost to reach module level to 15.59 dollars, the cheapest of all 6. But researchers could not calculate a full teardown cost for the Tesla pack at all, because how to safely undo the strong structural glue holding its cells together is not public information. The Tesla pack is the only 1 of the 6 with no full disassembly cost on record.
The best single module lost to the worst pack layout
The module inside the Nissan Leaf is the fastest of the 6 to strip down by hand, 16.4 minutes, and the only 1 that uses no welding at all inside it. But the whole Nissan Leaf pack spreads its wiring across 24 modules, connected by busbars, the metal strips that carry current between them, and needs 1,810 screws in total. That pack layout makes the Nissan Leaf pack the most expensive of the 6 per kilowatt hour, the unit that measures how much energy a pack can hold, at 4.85 dollars per kilowatt hour, and ties it with the Peugeot 208 for the most expensive full teardown in total dollars, 194.11 dollars against 186.35 dollars. The Peugeot 208 pack makes the identical mistake, spreading 18 modules across the pack and needing 24 busbars of its own.
The Renault Zoe figure is a pack to module cost only, not a full pack to cell total, because the paper does not state a full total for it as a clean number in its main results. The Tesla Model 3 pack is not shown here because the paper states its own total could not be calculated.
Show the numbers
| BYD Han | 47.41 |
| BAIC BJEV EU5 | 50.45 |
| Renault Zoe, pack to module only | 20.30 |
| Peugeot 208 | 186.35 |
| Nissan Leaf | 194.11 |
One professional team could not finish the job
A separate German field study tore down a real 2018 Mercedes Benz plug in hybrid battery pack by hand. Removing the cover meant cutting through 40 screws and a bead of glue. Inside, its 2 modules were glued to the base of the pack, for cooling, on top of 8 screws and 4 plugs each. The trained research team removed every other part of the pack and stopped there, because the tool needed to safely remove the glued modules was not available on the day.