Published on January 11, 2018
This small battery operated PIR light was drawing excess current in standby mode, runnning its batteries flat very quickly. The fault was interesting and unexpected.
Given the continuous standby current of 10mA at 4.5V I wondered if the rogue component dissipating the power would show up on a thermal camera. It did, and more interestingly it could also be detected by probing with a cheap thermocouple.
Ironically, desoldering the faulty component also made its fault clear, suggesting perhaps a moisture ingress issue.
A link to Mike’s epic Flir E4 teardown.
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