Spectro CA-12 Battery Rapid-tester

Spectro CA-12 battery rapid-tester estimates CCA and capacity. CCA (Cold Cranking Amp) refers to the ability to crank the engine; capacity, also known as reserve capacity, estimates electrical storage capability.

A battery test should include CCA and capacity. CCA discovers anomalies caused by heat failure or sulfation; the leading health indicator is however capacity.

Note: The Spectro CA-12 is currently only available to Original Equipment Manufacturers (OEM) to seamlessly integrate into warranty and after-market programs.


Why Starter Batteries Fail

Heat failure Heat promotes corrosion that reflects in high internal resistance and poor cranking. Sulfation caused by low charge also increases resistance. Sulfation can often be reversed with a slow, long charge.

Note: Batteries installed in the engine compartment and driven in hot climates show elevated heat failures. A CCA test identifies these batteries.
Capacity fade Battery capacity fades naturally with use and this goes unnoticed until the battery stops cranking. Replace the battery when the capacity drops to 40% to avoid possible no-start.

Battery Definition

A starter battery has three characteristics:
CCA: Responsible to crank the engine; illustrated by free-flowing tap.
Capacity: Storage of electrical energy in RC (Reserve capacity) or Ah, capacity loss is shown as a rock buildup.
SoC: State-of-charge reflects liquid level.

What goes wrong?

Starter batteries should last 4–5 years in normal use. Figures 3 demonstrates a battery that died because of heat failure; Figure 4 shows CCA and capacity fade on a quality battery as part of normal aging.
Figure 3: Heat failed battery.
Battery fails in 1-2 years due to corrosion, mechanical defect or sulfation.
Symptoms: Poor cranking due to high internal resistance. Failure mode is not sudden but progressive.

Test Method: AC conductance tester or equivalent. Shows low CCA reading.
Figure 4. Full 4–5 year life.
Battery fails due to capacity fade. CCA remains within the workable range.
Symptoms: Failure mode is sudden as capacity fade goes unnoticed. Capacity should be checked as part of preventative service.

Test Method: Spectro™ (only method to estimate capacity)

Capturing CCA and Capacity on a two-dimensional Table

A starter battery must have low internal resistance to supply cranking power and enough capacity to deliver energy. CCA and capacity can be presented on a two-dimensional table by plotting CCA on the vertical and capacity on the horizontal axis. Figure 5 demonstrates thee batteries with various conditions.
Figure 5: Battery evaluation based on CCA and Capacity.

Battery 1: Good capacity; high CCA. Battery performs well.

Battery 2: No cranking due to capacity fade. CCA in operational range. 

Battery 3: No or slow cranking due to heat failure or sulfation. Capacity may also be reduced. Failure premature.

A battery tester should examine CCA and capacity. CCA reflects resistance; capacity is the leading health indicator that also predicts end-of-life.

Capacity, the Leading Health Indicator

To study failure modes, a German luxury car maker tested 175 starter batteries. Heat failed batteries were eliminated and the results plotted in Figure 6.

As the table illustrates, most batteries pass through the Capacity Line on the left of the green field. Very few batteries failed by dropping through the CCA Line. Capacity fade occurs through normal use; auxiliary power such as start-stop, heating elements and mechanical door actions accelerate capacity loss.
Figure 6: Capacity and CCA of 175 aging starter batteries.

Most batteries pass through the Capacity Line; few fail because of low CCA. The test batteries were trunk mounted and driven in a moderate climate.

Note: Test was done by a German luxury car manufacturer. Heat damaged batteries were eliminated.  

Test Method: Capacity and CCA were tested according to DIN and IEC standards.
Evaluating a starter battery on CCA alone can pass a faulty battery as good, only to fail on the road, while a good battery is replaced in error. CCA alone cannot predict the end of battery life as CCA tends to say high while the capacity drops predictably. The Figure 7 below illustrates this with 20 aging batteries.
Figure 7: Comparing CCA and capacity of 20 aging batteries.

These random batteries cannot be tested by CCA alone; the readings are still above 70%. Only capacity estimation finds batteries falling below 40%.

Test Method: CCA was taken with Spectro CA-12; capacity was measured with an Agilent load bank by applying full discharges according to BCI standards.

Testing is Simple

To test a starter battery, select between flooded or AGM and then enter CCA and capacity ratings in reserve capacity (RC) or ampere hours (Ah). The battery should have a minimal state-of-charge of 50%. The non-invasive test takes 15 seconds; the pass/fail threshold using a generic matrix is set to 40% or other setting specified. (Numeric capacity reading is available with a battery-specific matrix.)

Why was this not done earlier?

Testing batteries with electrochemical impedance spectroscopy (EIS) is not new. High costs and long test times restricted the technology to laboratory use.

Multi-model electro-chemical impedance spectroscopy (Spectro™) infuses data obtained through a frequency scan with complex modeling to estimate capacity and CCA. There is no comparable product on the market capable of estimating capacity.

AC conductance sees only R1 of the Randle’s model in Figure 8; Spectro™ also estimates capacity by modelling R2 and C with the help of matrices.

Randle's Model
Figure 8: Randle’s model. R1 reflects heat fail; R2 and C reveal the capacity.
AC conductance and Spectro™ can be compared to an old X-ray machine and a modern CAT scan. While the X-ray is capable of reflecting shadowy outlines of the image taken; the CAT scan reveals soft tissues. Spectro™ provides preventive maintenance by estimating capacity on a well-performing battery with not fault symptoms present; AC conductance can only detect a fault that is present

Ordering Information

The Spectro CA-12 is currently only available to Original Equipment Manufacturers (OEM) to seamlessly integrate into warranty and after-market programs.

Cadex is continuously advancing Spectro™ in the form of improved battery diagnostics, broader test ranges, new battery types, and the distribution of test results. We are interested in your application and would be pleased to discuss your requirements.


  • Non-invasive hand-held rapid-tester for flooded, AGM, gel lead acid batteries, DC decoupled
  • Injects 20–2,000Hz sinusoidal signal at 10mV
  • Measures reserve capacity (RC), internal resistance and CCA at a SoC range of 60–100%
  • 15 seconds test time; tolerates 30A parasitic load
  • Generic matrix sorts starter battery on a 40% capacity threshold or as specified.
  • Reverse polarity and over-voltage protection
  • Internal Li-ion battery provides ~150 tests per charge
Range Resistance: 2–20mΩ
Voltage: 12V, flooded & AGM
Test CCA: 100–1,200
RC: 60–210 minutes; 30–105Ah
Physical 172 x 275 x 117mm (6.77” x 10.83" x .61"), 1.58kg (3.50 lbs.)
Ports RS232, Bluetooth
Safety UL3101, CSA 1010, EN61010 EMI/
EMC: FCC part 15 Class A, EN55011
Level A, EN61000-6-3:2001 for EMC
Warranty One (1) year against defects