Pokit Pro car battery load test with oscilloscope!
To measure your car battery, or any battery for that matter, under a load, set for oscilloscope mode. The proper settings will vary depending on your application but for the car battery I used 2.00 V DC/div and 500 ms/div. I set it for a one time falling trigger at 10.490 volts. I then started the car and when the voltage dropped below 10.49 volts it captures the drop and subsequent rise in voltage after the car starts. With the 500 ms/div time base it will display a 5 second span across the screen.
Here is a link to my YouTube video of the process
https://youtu.be/12vrlSuDsNU
Results were awesome. This will be very useful. Here is a screen shot of the result.
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FYI, I also tried the datalogging mode for this same test and 500 ms is not sufficient to capture enough data points. Here is a screen shot of the same test in datalogging mode. Only captures a couple data points during engine cranking, not enough to catch the low point. Maybe if you timed it perfectly it might but oscilloscope mode is far superior for this and multimeter mode with min function works great too.
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Terrific! Just what I was looking for!
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Any tips on measuring / observing ripple in the 12V supply in a car? I don't want to catch that initial drop, but I'd like to see how noisy the 12V supply is once the engine is running like what your graph shows for the end section?
I don't think I understand the trigger options well enough.
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Should be able to just watch the battery voltage with the oscilloscope in continuous mode and adjust the time base to see irregularities. Just like watching the ripple on a bench power supply. Rising or falling trigger probably wouldn't work well for this because that is looking for a change of xx volts to "take the picture".
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Nice job with the video and comparisons between the FLUKE and Pokit. This is a test I will use often. Thank you for the great explanation.
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