# How to Grade Used Batteries for a Second Life > This patent describes a system that reads electrical characteristics and usage history from a rechargeable battery module to determine if it's good enough to be used again for a different purpose, like energy storage. - **Patent:** US 9397374 - **Original title:** Secondary battery module, battery information management device, battery information management system, secondary battery reuse system, secondary battery recovery and sales system, secondary battery reuse method, and secondary battery recovery and sales method - **Owner:** Hitachi Automotive Systems - **Granted:** 2016 - **Status:** Active - **Times cited:** 4 - **Field:** automotive, energy, consumer_electronics, software, telecommunications ## What it does This patent describes a system for managing rechargeable batteries, called 'secondary battery modules.' Each battery module stores its own 'electrical characteristic information' (like its original capacity and how much it resists current) and 'usage history information' (like its voltage and current ranges over time) (Claim 1). A 'battery information management device' connects to these modules, reads this stored data, and then compares it to a 'predetermined threshold' (Claim 1). If the battery's information meets the threshold, the device 'grades' it as suitable for 'reuse,' meaning it can be used for something else after its first life, perhaps in an electric vehicle (Claim 1). For example, a device could read data from an old electric car battery, see its remaining capacity is above a certain level, and then grade it for use in a home solar power storage system. ## What it does NOT cover - Does not cover managing primary (single-use) batteries, only 'secondary battery modules' that are rechargeable. - Does not cover battery management systems that only monitor battery health without explicitly grading for 'reuse' based on predetermined thresholds. - Does not cover systems where battery characteristic and usage history information is not stored directly within the 'secondary battery module' itself. - Does not cover grading systems that do not use specific 'electrical characteristic information' and 'usage history information' as claimed. - Does not cover systems that simply charge or discharge batteries without reading and grading their internal information for reuse. ## The clever bit The clever part is combining on-board storage of detailed battery history with a centralized system that specifically grades these batteries for 'reuse' against predefined limits. This allows for an automated and standardized way to assess a battery's suitability for a second life, rather than just discarding it. ## Real-world examples 1. Nissan LEAF second-life battery projects 2. Tesla Powerwall (though not necessarily using this patent, it represents the market for repurposed batteries) 3. Energy storage systems for commercial buildings using retired EV batteries 4. Grid-scale battery storage solutions ## Why it matters As electric vehicles become more common, there will be a growing number of used EV batteries. This patent addresses the challenge of figuring out which of these batteries still have enough life left to be repurposed for other uses, like storing energy from solar panels or powering homes. By providing a structured way to assess battery health for reuse, it supports the development of a 'second-life' battery market, reducing waste and making better use of valuable resources. ## Frequently asked questions ### What does How to Grade Used Batteries for a Second Life cover? This patent describes a system that reads electrical characteristics and usage history from a rechargeable battery module to determine if it's good enough to be used again for a different purpose, like energy storage. ### Who owns patent US 9397374? Hitachi Automotive Systems owns this patent, granted in 2016. ### When does this patent expire? This patent is expected to expire on September 14, 2032, when the invention enters the public domain. ### What is patent US 9397374 cited by? This patent has been cited by 4 later patents that build on its ideas. ### What problem does this patent solve? As electric vehicles become more common, there will be a growing number of used EV batteries. This patent addresses the challenge of figuring out which of these batteries still have enough life left to be repurposed for other uses, like storing energy from solar panels or powering homes. By providing a structured way to assess battery health for reuse, it supports the development of a 'second-life' battery market, reducing waste and making better use of valuable resources. ### What does this patent NOT cover? Does not cover managing primary (single-use) batteries, only 'secondary battery modules' that are rechargeable. **Full plain-English explainer:** https://patentbrief.org/patent/us/9397374/secondary-battery-module-battery-information-management-device-battery-informati **Original patent:** https://patents.google.com/patent/US9397374 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How a System Tracks and Transfers Rechargeable Batteries Between Users](https://patentbrief.org/patent/us/20240186800/battery-management-system-battery-management-method-and-program) — This patent describes a system that verifies a rechargeable battery's actual capacity and then updates which user is associated with that specific battery, especially useful for shared or transferable batteries. - [How an EV Charging Station Manages Power from Batteries and the Grid](https://patentbrief.org/patent/us/9168838/charging-control-system-and-charging-control-method) — This patent describes a smart charging system for electric vehicles that decides whether to power cars from a local battery or the main electricity grid, and when to recharge that local battery, to help balance power demand. - [Smart EV Charging to Protect Battery Life During Long Parking](https://patentbrief.org/patent/us/11235681/curtailing-battery-degradation-of-an-electric-vehicle-during-long-term-parking) — This patent describes a system that intelligently discharges and recharges an electric vehicle's battery while parked for a long time, like at an airport, to prevent battery damage and ensure it's ready when the owner returns, using vehicle-to-grid technology. - [How to Fast-Charge Lithium Batteries Without Damaging Them](https://patentbrief.org/patent/us/10700376/methods-for-fast-charging-and-detecting-lithium-plating-in-lithium-ion-batteries) — This patent describes a three-phase method for quickly charging lithium-ion batteries while carefully controlling voltages to prevent harmful lithium metal buildup and electrolyte damage. - [How a Hybrid Layer Stops Metal Growths in Lithium Batteries](https://patentbrief.org/patent/us/10566652/lithium-metal-battery-with-hybrid-electrolyte-system) — This patent describes a special multi-layered electrolyte system for lithium metal batteries that uses a stiff, hybrid material to block dangerous metal growths, aiming for safer, higher-energy batteries.