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Lead acid batter testing
May 05, 2017

Testing Lead Acid Batteries


Discover developments in non-invasive rapid-test technologies.

There are no shortages of battery testers, but most lack accuracy. Capacity, the leading health indicator of a battery, is difficult to obtain on the fly. Stating that a battery tester measuring internal resistance will also provide capacity estimation is misleading. Advertising features that are outside the equipment’s capabilities confuses the industry into believing that complex tests can be done with basic methods. Resistance-based instruments can identify a dying or dead battery — so does the user. Vendors often overstate the ability of battery testers knowingly. This is similar to promoting a shampoo that promises to grow lush hair on a man’s bald head.

Without reliable test devices on hand, battery testing becomes guesswork, resulting in good packs being replaced too soon and passing weak ones, only to have them fail on the road soon after checking. Lack of accurate battery testing also causes unnecessary replacements under the battery warranty program. Examining warranty returns reveals that less than 10 percent of these batteries have a manufacturing fault. Most faults are user-inflicted. 

The challenge arises when assessing a battery as part of routine service before performance degradations are noticeable. Such a test is only effective when including capacity measurement. Capacity oversees the energy storage, governs the runtime and predicts the end-of-life. Internal resistance, on the other hand, is responsible for the power to crank the engine and deliver high current under load on demand. A snapshot taken with a CCA tester on a starter battery refers to the resistive battery condition only. Better electrolytes and corrosion-resistant electrode materials are keeping the resistance on modern batteries low through most of their life. Failure due to elevated resistance has become rare and may only develop at the end-of-life.
Unlike voltage, current and ohmic measurements, no universal instrument exists that can read the capacity of every battery that comes along. There are three common testing concepts: Scalar, vector and EIS with complex modeling (Spectro™).

Scalar is the simplest of the three. It takes a battery reading and compares it with a reference that is often a resistive value. Most single-frequency AC conductance testers measuring CCA are based on the scalar concept.

The vector method applies signals of different currents or it excites the battery with varied frequencies, and then evaluates the results against preset vector points to study the battery under various stress conditions. This adds complexity and the added benefits are marginal.

Spectro™ scans the battery with a frequency spectrum, as if to capture the topography of a landscape, and compares the imprint with a matrix to estimate battery capacity, CCA and SoC. Spectro™ promises the most in-depth battery analysis, but it is also the most complex. Figure 1 summarizes the three battery test methods.







Single reference point; pulses or single-frequency   excitation

Automotive, stationary; simple, commonly used

Voltage, CCA, internal resistance, no capacity


Multiple frequencies, currents; compares against vector

Automotive, stationary; less commonly used

As above. More complex with marginal gain


Combines EIS with complex modeling; fuses data to   derive at capacity, CCA, SoC

Lead- and lithium-based batteries

Provides CCA, capacity and SoC with appropriate   matrices

Figure 1: Methods of data collection for battery rapid-testing. The table compares scalar,

vector and Spectro™ which combines electrochemical impedance spectroscopy (EIS) with complex



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