CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

Battery construction, anode overhang, and CT insights

• Commenters found the PDF report crucial to understanding “anode overhang” and alignment: cylindrical cells are rolled layers of anode and cathode, and you want a consistent anode edge protruding beyond the cathode to avoid internal shorts.
• Misalignment/negative overhang is linked to higher short-risk; some connect this to known phone battery fire incidents. CT makes such defects visually obvious and suitable for QA by serious pack makers.
• The stats quoted in the thread suggest that all severe overhang defects came from low-cost/counterfeit brands, while name-brand OEM cells were clean and rewraps were intermediate quality. Whether this is due to diverted rejects going to rewrappers is raised as a hypothesis but remains unclear.

Capacity testing and voltage cutoffs

• There’s disagreement over the report’s “advertised vs actual capacity” table, which used a 3.0 V cutoff.
• Critics say this unfairly under-reports capacity (many datasheets rate to 2.5–2.7 V), especially for certain brands.
• Others argue 3.0 V is a conservative and realistic benchmark because many devices (3.3 V rails, battery managers) stop drawing power above that anyway and low-current curves don’t gain much extra capacity below 3 V.
• Detailed comparison with one Vapcell datasheet suggests at least some cells truly underperform even by the vendor’s own spec.

Safety, fires, and handling practices

• Experiences range from “modern quality 18650s are hard to ignite, even when abused” to multiple anecdotes of e-bike and toy battery fires and swollen pouches.
• Consensus: brand and supply chain matter more than anything; top-tier manufacturers (Samsung, Panasonic, LG, Sony, Molicel) are widely trusted, while cheap cells and unknown packs are risky.
• Pack design is highlighted as a major failure point: poor welds, loose balance wires, inadequate insulation/spacing, and weak or absent BMS can turn good cells into a fire hazard.
• Internal resistance (Ri/IR) plus thermal monitoring (e.g., FLIR) are favored as ongoing health indicators; CT is seen as more of a one-time QA tool.
• Old fully discharged puffed cells are less energetic but still chemically hazardous; commenters advise outdoor handling and proper recycling.

CT scanning practicality and Lumafield business model

• Some are surprised CT is used in manufacturing QC; others note microCT is common but can be slow for dense, high-resolution scans.
• Lumafield representatives state battery scans can be sub-second with ~5-second total cycle times.
• Pricing (subscription around $75k/year) is seen by some as too high, but others compare it favorably to traditional $300k–$1m CT systems plus annual maintenance.

Chemistry choices and application trade-offs

• Safer chemistries like LFP and sodium-ion are noted as increasingly viable, especially for bulk storage and lower energy-density needs.
• However, commenters point out current limitations in power density and peak current, making NMC-type cells still preferred for tools, drones, and other high-power applications.