BU-926: Battery Diagnostics, an Overlooked Requirement

Much attention goes into improving the battery, but Diagnostic Battery Maintenance is overlooked. Yes, batteries are clean, but reliability is low that causes half of failures. As capacity fades, Minimum Operational Reserve Energy (MORE) is often overlooked. MORE assures the full use of each battery with calls for replacement before failure.

A US FDA survey says: “Up to 50 percent of issues in hospitals are battery related.” Listed shortcomings are: Deficiency in quality assurance in batteries by device manufacturers; lack of understanding in battery system integration, and not knowing the end of battery life. AAMI endorses the finding by saying: “Battery management emerged as a top ten medical-device challenge.” Service centers repairing scanners further say that half of failures are caused by batteries, a phenomenon I experienced working at GE servicing two-way radios where batteries also caused half of failures.

Without battery diagnostics, device manufacturers ask to replace a battery after five years from date of manufacturing or 500 cycles. In real life, batteries are replaced either too late or don’t get the full life. A DOE official said: “Every year roughly one million usable lithium-ion batteries are sent for recycling.” The EV changed life perception by mandating an eight-year battery warranty or driving 100,000km.

*Battery disposal in Kuwait by the US Army*

Records reveal that batteries in armored vehicles were replaced every 13 months instead of an expected life span of six to eight years. In 2016 alone, the U.S. Department of Defense replaced over 373,000 batteries from a pool of 400,000 at a cost of over $80 million for lack of battery diagnostics (Link). A 2024 report by ADAC (Allgemeinder Deutscher Automobil-Club) states that the starter battery are the cause of 45 percent of all vehicle breakdowns.

Common failures do not have to be common

Cadex has developed diagnostics technologies for portable, mobile and stationary batteries. Smaller batteries are served by the System Management Bus (SMBus) that estimate battery capacity by coulomb counting. Scientists predict that large batteries will be tested by Electrochemical Impedance Spectroscopy (EIS), a technology that is of special interest to Cadex with the development of Spectro™, a patented technology using Multi-model EIS that is in commercial use assessing battery capacity non-invasively.

Spectro Technology

Most starter batteries are checked with a load test, but the argument goes: “If the vehicle starts, no further testing is needed — but can I start again tomorrow?” A load test only checks CCA while capacity, the leading health indicator, is unknown. A Johnson Control study reveals that low capacity causes 47 percent of all failures.

Spectro™ models a battery against a matrix to assess capacity and other data with Multi-Model EIS. Matrices for different battery chemistries are made by scanning same-type batteries of different state-of-health Testing batteries by frequency and assessing the Nyquist Plot opens a standard. that resembles face recognition.

A Spectro battery tester is loaded with a matrix of choice. Other matrices can be downloaded from the Matrix Library with Cloud Analytics, a web app that also stores test data to share with fleet supervisors. Identifying batteries with a QR code simplifies viewing historic data and the downloading of the assigned matrix.

Most starter batteries are tested with a MORE of 40%; a value that is set higher when hotel load is needed in transit buses and long-haul trucks. A pass gives a grace period that is good to next service, while a fail requires replacement even if cranking abilities are still strong. In most cases, low capacity provides still strong cranking but failure occurs when battery capacity drops below 30 percent.

EIS Direct Drive

A further Spectro development is the EIS Direct Drive servicing batteries up to 500Ah. The compact test device stays cool during the 30 second. test as the applied ripple current only draws 500mA. Scanning frequencies to 4Hz serves batteries up to 300Ah; lower frequencies test larger packs will longer test times. Test data can be stored in the Spectro device or downloaded into Cloud Analytics.

EIS 926 — *EIS Direct Drive test large batteries at low frequencies*

Test accuracies rest on the Matrix Integrity Level (MIL) rated from 1–10. MIL 2–3 provide classification and 4–5 give tri-state of Pass, Fair and Fail. Further developments with model-specific matrices will give capacity assessment in numerical readout.

Batch Test

Wheeled mobility is commonly powered by serial connected batteries. Runtime is only as good as the weakest link. Batch Test measures capacity with leftover charge reflecting capacity. Battery 3 in our example fell below MORE and has low state-of-charge (SoC) because of low capacity. In comparison, the SoC bars of a well-matched battery would be even.

Pass fail 926 — *Weak battery in a string is marked in red*

SoC with Spectro™ must be at least 50 percent to assess capacity. Allowing some discharge before the test gives the most reliable Batch Test. A common MORE setting for deep cycle batteries is 60%. Matrices for other thresholds can be made available.

Spectro CM-24

The battery tester in question deploying Multi-model EIS is the Spectro CM-24 shown on the right that serves as an open platform to test virtually any battery with a matrix of choice. Cadex provides the matrices with availability of used batteries.

Spectro Explorer

The economically priced Spectro Explorer also views the Electrochemical Evidence of a battery to check battery anomalies by displaying the Nyquist plot for visual examination. The test range is up to 60V, 500Ah and 300µΩ with a frequency scan from 2,000Hz to 100mHz..

Applications are quality control in battery fabrication; finding anomalies in laboratories; doing incoming quality inspection, and validating warranty claims.

Spectro Explorer 926 — *Nyquist plots of 100 overlaid 18650 cells*

Conclusion

Batteries lower greenhouse gases but this is only achieved by fully using each battery with call to replace before failure. Battery diagnostics is lagging behind other technologies. Performance transparency in electrification must be equal to fossil fuel power by revealing MORE.

When asking a battery user: “At what capacity do you replace the battery?” a common reply is: “I beg your pardon.” The term MORE is not well understood as the remaining useful life of a battery is mostly hidden.

Last Updated: 13-Apr-2026

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Batteries In A Portable World

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