How is CCA tested on a battery?

Two ways. The factory rating test discharges a fully-charged battery at the rated current for 30 seconds at −18°C (0°F) and checks the voltage stays above 7.2V (SAE J537). The field diagnostic test uses a load tester (typically half the rated CCA for 15 seconds, voltage should stay above about 9.6V) or a conductance tester that measures internal resistance to estimate CCA.

What voltage is a pass on a CCA load test?

A common field rule is that a battery loaded at half its CCA rating for 15 seconds should hold above roughly 9.6V at room temperature. A reading well below that indicates the battery can no longer deliver its rated cranking current.

Lead-Acid Knowledge · CCA Cluster · Last reviewed 2026-09-14

How CCA Is Tested: The Rating Test vs the Diagnostic Load Test

"Testing CCA" means two different things. There is the factory rating test that produces the number on the label, and the field diagnostic test that tells you whether a used battery can still deliver it. They use different equipment, different loads and different pass criteria — and confusing them is a common mistake.

Direct answer: The rating is determined at the factory by discharging a fully-charged battery at its rated current for 30 seconds at −18°C and confirming the voltage stays above 7.2V (SAE J537). In the field, a technician checks a battery with a load test — typically half the rated CCA for about 15 seconds, expecting the voltage to hold above roughly 9.6V — or with a conductance tester that reads internal resistance and estimates CCA without a heavy discharge.

The factory rating test (SAE J537)

The printed CCA is a specification measured once, under controlled conditions. A battery that is to be labelled "600 CCA" must be cooled to −18°C (0°F), discharged at 600 amps, and hold at least 7.2 volts for 30 seconds. The 7.2V floor is 1.2V per cell — the point below which a starter motor no longer turns reliably. This is a laboratory test, not something done at the roadside.

Related ratings (CA, MCA, HCA) run the same procedure at warmer temperatures, which is why their numbers are higher.

The field diagnostic: load test

A shop does not re-run the −18°C rating. It runs a load test at room temperature: a carbon-pile or fixed-resistance tester applies a load — a common rule is half the rated CCA for about 15 seconds — and the technician watches the voltage. A healthy, fully-charged battery should hold above roughly 9.6V during the test. A reading that collapses well below 9.6V means the battery has lost its ability to deliver cranking current — regardless of what the label still says.

The load must be proportional to the battery's own rating: a fixed 100A load means nothing without knowing whether the battery is a 300 CCA or an 800 CCA unit. This is why testers are set to the battery's rated CCA before the test.

The field diagnostic: conductance testing

Modern handheld testers use conductance: they send a small AC signal through the battery, measure the internal resistance (and sometimes a temperature reading), and estimate CCA from that. It is fast, non-destructive and does not require a full charge first, which is why it has replaced the carbon-pile load in most shops. Its weakness is that it is an estimate — the correlation between conductance and true cold cranking ability is strong but not perfect.

What skews the result

State of charge — a load test on a partially-charged battery reads low; the battery must be fully charged (or corrected) first.
Temperature — a cold battery delivers less current, so a test run in a freezing bay reads lower than the same battery warm.
Age and sulfation — accumulated sulfation raises internal resistance, which is exactly what a conductance test detects.

Common misconceptions

"The label CCA is what the battery still delivers." No — the label is the rating it delivered when new; the diagnostic test tells you what remains.
"A conductance test measures CCA directly." It estimates CCA from resistance; it is a strong proxy, not a direct measurement.
"Any load test works on any battery." The load must be set to the battery's rated CCA, or the pass/fail threshold is meaningless.

Key takeaways

The rating test (SAE J537) is a one-time −18°C laboratory discharge to 7.2V; the diagnostic test is a room-temperature health check.
The field load test uses about half the rated CCA for 15 seconds, expecting ≥~9.6V.
The conductance test estimates CCA from internal resistance — fast, but an estimate.
Charge and temperature must be accounted for, or the reading is meaningless.

The Author's Take

Position: The most useful thing to understand about CCA testing is that the label number is a birth certificate, not a current health report — and only a load or conductance test tells you which one you are holding.

Reasoning: A battery does not lose its label as it ages; it loses its ability to meet it. The diagnostic test exists precisely to measure that gap. A buyer or technician who trusts the sticker instead of the test is making a decision about a battery's present state using information about its past — which is why any serious battery decision starts with a test, not a label.

This is the author's editorial view, not a purchasing guarantee.

Sources

Cross-verified from primary standards and secondary references; the half-CCA / 15-second / 9.6V load-test figures are stated as typical field practice because exact thresholds vary by tester and battery type.

SAE J537 — cranking-ampere rating method (−18°C, 30 s, 7.2V).
Battery Council International (BCI) — battery testing and rating guidance.
Platrex, Jump Charge HQ and battery-tester manufacturers — load-test and conductance-test procedures.

Last reviewed: 2026-09-14