01 · QUESTION / INTENT
Remove hidden differences in temperature, SOC, C-rate and end-of-life definition before ranking cells.
02 · DIRECT ANSWER
A cycle count is comparable only when chemistry, cell model, temperature, charge/discharge rate, SOC window or DoD, rest time, compression, end-of-life threshold and sampling/statistics are aligned. If conditions differ, use raw curves or request a common test—not a ratio between headline counts.
03 · DECISION TABLE
| Decision factor | Decision direction | Confirm before approval |
|---|---|---|
| Test boundary | Align all operating conditions before comparison. | Protocol, chamber conditions, fixtures and measurement intervals. |
| Life endpoint | Use the same capacity/SOH and resistance limits. | Whether life ends on capacity, power, resistance or safety limit. |
| Statistics | Compare distribution and confidence, not a single best cell. | Sample size, failures, censoring and lot representation. |
04 · ENGINEERING EXPLANATION
Build a normalisation sheet with every test variable. When a vendor cannot supply a common-condition result, model the gap conservatively and make the comparison provisional until samples are tested in the project’s own envelope.
05 · APPLICATION / MARKET MAPPING
BESS may emphasise calendar plus daily cycling; commercial mobility may emphasise fast charge and route peaks; industrial equipment may emphasise partial cycles, vibration and long idle periods. Equal conditions must reflect the target mission.
06 · EVIDENCE AND TEST CONDITIONS
- Full test protocol and time-series capacity/resistance data.
- Sample count, lot identity, failure handling and EOL definition.
07 · RISKS / NOT SUITABLE WHEN
- Avoid multiplying a cycle count by nominal kWh to claim lifetime throughput without efficiency and usable-window corrections.
- Short accelerated tests may not capture calendar ageing or field interactions.
08 · FAQ
Can two vendors' graphs be overlaid?
Only after the axes, protocol, temperature, sampling and EOL definitions are confirmed equivalent.Which metric matters besides capacity?
Resistance growth, power capability, energy efficiency, swelling and thermal behaviour can become the binding limit.BUYING COMMITTEE ANSWERS
Engineering
Own the normalised protocol and project-envelope test.Procurement
Make comparable evidence a bid deliverable.Quality
Review samples, lots, failures and data integrity.Compliance / Logistics
Confirm any test method referenced by a certification or route requirement.Finance / Project
Translate degradation distributions into energy, augmentation and downside cases.Management
Do not approve a ranking built from non-equivalent headline claims.10 · PROJECT CTA