Fremont, California cell grading plant
How Fremont — California Diagnostics Works decides reuse or refining for every module — test sequence, grade bands, outputs and the sites that feed it.
Throughput
24,000 TPA
Process stages
6
Feeder sites nearby
6
Operating since
2020
From intake to grade assignment
- 1
Intake & safety triage
Packs are logged, thermally imaged and screened for swelling, coolant ingress or venting before entering the bench area.
- 2
Controlled de-energising
Residual energy is discharged to a safe state of charge with regenerative load banks and recorded per serial number.
- 3
Module-level capacity test
Full charge-discharge cycling at C/3 establishes usable capacity, internal resistance and cell-to-cell balance.
- 4
EIS fingerprinting
1 mHz–10 kHz impedance sweeps separate SEI growth, lithium plating and contact resistance degradation modes.
- 5
AI optical inspection
Machine-vision inspection of busbars, welds and cell cans flags mechanical defects that block second-life reuse.
- 6
Grade assignment
Grade A (≥85% SOH), B (75–85%), C (65–75%) and D routes are assigned, with D-grade material released to refining.
Acceptance criteria
| Criterion | Requirement |
|---|---|
| Accepted feed | Whole packs and modules from intake yards and fleets |
| State of charge | Below 30% on arrival, recorded per serial |
| Condition | Damaged units declared and routed to quarantine |
| Documentation | Manifest with serials, chemistry and prior history |
Grade bands and routes
| Grade | Route |
|---|---|
| Grade A (85%+) | Grid-tied and commercial storage builds |
| Grade B (75–85%) | Telecom backup and solar buffering |
| Grade C (65–75%) | Low-duty backup, short warranty |
| Grade D (<65%) | Discharge and refining feed |
Why Fremont, California
Fremont sits in the southern East Bay, part of a Bay Area cluster that combines vehicle production, battery start-ups and energy storage developers. The diagnostics works opened on Fremont Boulevard in 2020 to grade packs from California, the largest EV market in the United States, where many of the earliest mass-market electric cars are now reaching the end of their road life.
With 24,000 TPA of capacity, the works tests large volumes of passenger-car packs from dismantlers, dealers and fleets. Its location also suits pilot-line and R&D material from Bay Area companies developing new cells and packs, while Grade A modules find a ready market in California's strong demand for energy storage. Dismantlers are a large and steady source of the site's intake, bringing packs already removed from vehicles.
Permitting
EPA universal waste rules, DOT hazardous materials regulations and state programmes
The works operates under California's demanding hazardous-waste regime, overseen by the Department of Toxic Substances Control, alongside local permitting. California has also legislated towards producer responsibility for EV batteries, so records are kept in a form that supports evolving requirements. Transport follows US DOT hazardous materials rules.
Technical strengths
Largest US EV market
Serves California, where many of the first mass-market EVs are now retiring.
R&D material handling
Accepts experimental cells and packs from local technology developers.
Storage-market supply
Grade A modules feed California's strong demand for energy storage.
Sites that feed Fremont, California
Packs and modules arrive from these intake sites.
Fremont, California plant: technical questions
How long does grading take?
Standard passenger modules are graded within about five working days of intake; large-format bus and truck packs take longer because of disassembly.
What tests are run on each module?
A full capacity cycle, DC internal resistance, impedance spectroscopy and optical inspection of busbars, welds and cans.
Does Fremont accept prototype cells?
Yes, with a declaration of chemistry and known hazards so they can be handled safely.
Why is Fremont's documentation so detailed?
California applies demanding hazardous-waste rules, so complete records are kept for every consignment.
Damaged or defective packs are handled under a separate quarantine protocol — flag them in the form and the team calls you back the same day.
Need modules graded?
Share pack counts, chemistry and condition for a grading slot and indicative value split.