Toyota is recycling old EV batteries to help power Mazda's production line

Toyota–Mazda Relationship and Corporate Context

• Commenters note Toyota holds a significant voting stake in Mazda and has long-standing tech and manufacturing collaborations.
• Broader context: Toyota has similar cross-shareholdings/partnerships with Subaru, Suzuki, Daihatsu, etc., and Japanese corporate bylaws can give effective control with ~33% ownership, depending on quorum rules and poison-pill provisions.
• Some confusion over “who really owns Mazda” is clarified: Mazda is independent but closely tied via equity and joint projects.

What the Project Actually Is

• Multiple comments stress the system powers a Mazda factory, not Mazda EVs.
• Old EV batteries (from various chemistries and sources, not only Toyota cars) are used as stationary storage, where weight and energy density matter less than in vehicles.

Second-Life Batteries: Feasibility and Degradation

• Many see factory/grid storage as a strong second life for “worn” packs at ~70–80% of original capacity.
• Degradation is non-linear at cell level; packs often fail due to a few bad cells or modules.
• Disagreement over how much repair is done: some argue no one replaces individual cells and instead disable modules or arrays; others say in large stationary systems it can be cost‑effective to cull and reconfigure modules.
• Safety/fire risk is a recurring concern: suggestions include spacing packs, steel or concrete enclosures, strong monitoring, and treating facilities with precaution similar to other high‑risk infrastructure.

Mixing Ages and Chemistries

• The article’s “sweep storage system” is interpreted as sophisticated current‑limiting / MOSFET-based control to safely combine different battery types and degradation states.
• Several note that this is technically complex: balancing, different internal resistances, and chemistries make control and software non‑trivial, but lower discharge rates in stationary use help.
• Some say this scale and partnership (Toyota + JERA + universities) indicates it’s more than a PR stunt.

Mazda’s Environmental Posture

• One thread questions why Mazda, seen as weak on EVs, is involved; others reply that the project is about factory energy and that Mazda has a history of process‑focused “green” initiatives.
• Views differ on whether Mazda’s broader tech bets (rotary, Skyactiv, PHEV strategy) are admirable innovation or often commercial dead‑ends.

Recycling vs. Repurposing

• Several argue this is not true “recycling” but repurposing/upcycling; real recycling only happens when packs are eventually broken down into raw materials.