Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)

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By Sum~guy
#83054 I've been working lately trying to battery-power one of those small 01s modules to use the module as a beacon (ie - if it's powered up and accessible on the the network, it means something has happened, otherwise it remains off / unpowered). I had some 18650 batteries lying around so I took one that was mostly fully charged (it read 3.95 volts) and I figured I'd just wire a diode in series to power the 01s module. I chose a 1N5819 (schottky) that's rated for 1 amp. I wired it up, flipped a power switch, and the diode immediately gave up it's magic smoke. Naturally I was surprised by this. I tried another diode - same thing. I then tried a 1N5822 - also a schottky but rated for 3 amps. This worked.

The voltage drop across the diode was .3 volts, so the 01s module was getting 3.65 volts. I figure as the battery wore down over time the voltage would drop and get closer to 3.3 volts, but as it was the 01s module ran fine at 3.65 volts.

I then put an amp meter in the circuit and got a reading of 25 to 70 milli-amps over the space of 5 seconds. These 8266 modules obviously don't exhibit steady current consumption. I'm sure the blinking LED (to indicate wifi connection) played some role in the fluctuation. I've flashed the module with tasmota sonoff-sensors.bin. I imagine that different firmware will result in different operating current draw.

But the initial power-up current draw (which my meter is not capable of measuring) must be huge to blow a 1-amp diode. Any comments?
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By btidey
#83059 I would suspect the diodes. The module should only take a maximum current of 400mA and then only for a very short time. Normal active current is around 80mA as you measured.

With a fully charged 18650 you might get 4.2V and with a low drop diode you are definitely well over the top voltage limit for the module. Even if it works it will significantly increase the deep sleep current. Using an LDO instead of a diode is still very cheap and ensures the module is operating within limits.