Can a PicoScope be used to test my vehicle battery?

The straight forward answer here is most certainly yes, along with the starter motor and alternator in one very simple automated test.

While the PicoScope is packed full of features allowing the user to zoom, measure, scroll and scale through events faster than the blink of an eye, we tend to forget the basics. In the form of an automated test PicoScope’s processing power can be put to good use by anyone, with little to no
oscilloscope knowledge.

The PicoDiagnostics program is included within the PicoScope 6 Automotive software when downloaded and installed (for free) from our website at

Contained within our PicoDiagnostics software are various automated tests of which a Battery Test is just one.

Using a single test lead connected across your battery and a high current clamp connected around the main battery power cable, we are able to test three major components responsible for battery failure.

Battery-Starter Motor-Alternator

Above is a typical connection diagram applicable to the PicoDiagnostics battery test.

The real beauty of the battery test is the ease of setup. Requiring the user to simply connect the test leads and current clamp as above whilst entering the vehicle battery specifications found on the relevant battery I.D label, and selecting Start from the setup menu.

The user is then prompted to crank and start the engine where the software will monitor the initial battery voltage, the voltage drop during cranking, the starter motor current consumption and battery recovery/charge rate once the engine has started.
(3 component tests in less than 15 seconds)

Above is a typical Battery Test result sheet confirming the battery, starter motor, and alternator are all functioning correctly. This can be seen by way of the easy-to-read traffic light system. Any failures are clearly identified in red whilst amber indicates attention is required to a component and green indicates a pass.

So how does the battery test work?
The initial test carried out by the software is the battery open circuit voltage (OCV) as recorded at the battery connections via Channel A of the scope. From this input alone it calculates the state of charge of the battery (SOC). Once the software is happy with the SOC, starting the engine will load the battery sufficiently to evaluate the battery condition and capacity. At this point the condition of the internal resistance of the starter motor assembly is revealed based upon the lowest recorded voltage during cranking, and the value of the inrush current into the starter motor.

Plotting voltage against current in this fashion gives a real dimension to the
efficiency of the battery and the integrity of the starter motor in one very simple and rapid test.

Once cranking is complete and the engine has started, the software can
calculate the recovery rate and efficiency of the battery, the charge rate of the
alternator, and the amount of consumption upon the alternator in relation to its maximum output (80% in the test results below).


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Published on: December 12, 2016

Filled Under: Batteries, Technical Articles

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