Electronic Battery Load Tester

The BLT600A Battery Load Tester works by placing a heavy electrical load on a battery and measuring how much current/voltage the battery can deliver and how well it holds its voltage while doing so.

This is the same principle used to determine whether a battery has enough power to start an engine, which is why auto-electricians commonly rely on this type of testing to assess battery health.

When using the BLT600A, the user selects the battery size (Amp-hour rating), typically between 40Ah and 200Ah. Based on this setting, the tester can compare the measured current and voltage against values shown in the manual. If the battery meets or exceeds these values, it passes the test.

Many professionals prefer this type of tester because it operates in a similar way to traditional carbon-pile load testers. Unlike small handheld testers, the BLT600A actually draws a high current from the battery, which closely simulates real-world conditions such as starting a car. This provides a direct and practical measurement of the battery’s ability to perform under load.

Smaller battery testers often use a different approach called conductance or impedance testing. These testers send a very small electrical signal into the battery and then estimate its maximum starting capability based on internal resistance. While this method is fast and convenient, it does not place the battery under real load, so the result is an indirect calculation rather than a physical test of performance.

Because the BLT600A draws high current, test results may vary slightly from one test to another. This is normal and reflects the natural electro-chemical behaviour of lead-acid, AGM, gel, and calcium batteries. With repeated and consecutive testing, the battery voltage will gradually drop, as energy is being drawn from the battery in short but intense bursts — just like when starting an engine.