As Christmas nears, the temperature in the northern hemisphere is getting cooler and this often leads to problems starting a car. In 2010, ADAC (Allgemeiner Deutscher Automobil-Club) published a report of typical vehicle failures with these common breakdowns: 42%   Battery, alternator, starter 20%   Motor management 7.6%  Motor mechanical 6%     Locks 5.6%  Fuel system

Failure with starter battery still gets attention

We learn that battery problems in cars are still increasing. The 2021 ADAC report states, "Battery issues directly caused 46.3% of over 3 million breakdown incidents.” As the world electrifies, developing capacity-based battery diagnostics is gaining importance. Our focus is in offering innovative products that users may not yet realize will be needed. The Spectro CM-12 checks battery conformity by MORE (Minimal Operational Reserve Energy) by assuring sufficient capacity as the battery ages. In many ways MORE resembles Reliability-centered Maintenance (RCM), a standard that was developed in the 1960’s to track wear-and-tear of machinery.

Spectro CM-12 reads battery capacity and CCA

RCM was first applied to the Boeing 747 to lower maintenance costs and improve safety. The safety standard has since been adopted by nuclear plants, military, healthcare, and train services.

MORE relies on battery capacity that Spectro CM-12 assesses with a non-invasive frequency scan by taking the electrochemical evidence of a battery. MORE defines how low a battery capacity can fade before service becomes unreliable and replacement is needed.

With starter batteries, a pass on the classified readout of the Spectro CM-12 provides a grace period that is good to the next service and calls for replacement when the capacity drops below a minimal set threshold while the battery may still crank well.

Spectro™ measures battery performance by capacity, as well as CCA to assure sufficient cranking power. Capacity and CCA readings do not correlate well with the battery ages. CCA tends to stay high while capacity decreases predictably. CCA is commonly tested by measuring the internal resistance. Measuring CCA alone without assessing capacity, the leading health indicator, will not provide assurance.

Validation-testing for new technologies in batteries is similar to a pharmaceutical product in which the drug company is looking for patients suffering from a unique illness to measure the effectiveness of new medicine. With Spectro, we search for starter batteries that have strong cranking power but are at the end of life due to low capacity.

In 2017, Johnson Controls in Germany tested 800 retired AGM batteries and found that 48% failed by capacity as illustrated in the chart on the right. Capacity fade goes mostly unnoticed and often leaves drivers stranded. According to the study, low charge ranks at 23% which might be caused by a faulty charging system or a shorted cell that lowers the voltage at full charge. Low CCA accounts only for 12% of failures in the JCI test with starter batteries. Spectro™ assesses capacity by electrochemical impedance spectroscopy (EIS) while rival devices use a more basic load method. In evaluating the cause of failure we stress the importance of capacity assessment. Full reports are at: AABC Europe 2017 Johnson Controls Jörn Albers (cii-resource.com)

Johnson Controls Power Solutions EMEA; AABC Europe 2017, Germany

How low can the capacity drop and still enable cranking?

A fading starter battery stranded me after a Cadex Christmas party, but my staff got me going with starter cables. Testing the failed battery in the Cadex lab revealed a full-charge capacity of 26%. This appears to be the minimal threshold to crank the engine. To provide a grace period, Spectro CM-12 sets the pass/fail at 40%.

Modern vehicles come with a BMS (Battery Management System). Exploring how well a BMS can assess capacity, I exchanged information with Dr. Pilatowicz of RWTH in Aachen, Germany, who explored the effectiveness further. In his Failure Detection and BMS for Lead Acid Batteries report, Grzegorz confirms that a BMS is unable to read the capacity of a starter battery. The end of battery life is predicted by an offline method with a hard-coded cycle count. The online method based on voltage and internal resistance measurements will identify battery anomalies only.

Conclusion

Spectro™ works well to identify starter batteries with low capacity. A CCA test may assure power but the success might not be repeatable next week or a month from now. The grace period that Spectro™ offers with capacity assessment provides assurance that a power test with CCA alone cannot be secure.