Skip to main content

Current draw of a D1 Mini in deep sleep

To measure the deep sleep current draw of the D1 Mini, I hooked up 4 NiMH AA batteries in series (~5.2V) to its 5V and GND pins.

The sketch uploaded to the D1 Mini was a nominal:

void setup() {
  ESP.deepSleep(60)*60*1000000UL, WAKE_RF_DEFAULT);

void loop() {

The current draw was a pretty steady 0.8mA, or 800uA. That's a obviously a far cry from the sub-100uA reportedly achievable with the barebones ESP-01 due to all the extra components on the D1 Mini.

Reported deep sleep current draw for the D1 Mini is all over the place, from 0.21mA (5V), to 0.3mA (3.3V), to 6mA (USB)!


1. Connecting a 18650 battery (~4V) to the 5V pin did not work. In theory, the MC6211 LDO used by the D1 Mini means anything higher than 3.56V should work. But when connected, the onboard LED started to flash in a slow but erratic fashion, I suspect it is randomly resetting (because each time the D1 Mini powers up, the onboard LED flashes briefly).

2. Connecting a 18650 battery to the 3.3V pin did work, though in theory it shouldn't be done because the 3.3V is not connected to any voltage regulator. So the 4V goes directly to the ESP8266, which has a theoretical upper limit of 3.6V. But it did work for me (others have reportedly connected up to 5V to the ESP8266 with no problems, but don't push your luck!), and the deep sleep current draw was ~1.5mA. I suspect if I could hook up a regulated 3.3V source to the pin, the deep sleep current draw should fall closer to the 0.8mA range.

3. Connecting 2 x alkaline AA (3.2V) to the 3.3V pin did not work. The onboard LED started to flash erratically again. In theory, this should work, since the ESP8266 has a minimum operating voltage of 2.5V, but there have been many reports of the chip being finicky with the input voltage, so who knows.


Popular posts from this blog

Update: Line adapter for Ozito Blade Trimmer

Update (Dec 2021): If you access to a 3D printer, I would now recommend this solution , which makes it super easy to replace the trimmer line. I have been using it for a few months now with zero issue.

Filament Joiner Part 2 (With Display and Knob)

Thanks to the current corona-virus crisis, the parts I ordered for the filament joiner project were taking forever to arrive. But now that they have finally arrived, I can put them to good use. These were the parts ordered: 0.96" OLED display SSD1306 Rotary switch encoder KY-040 Here is the final circuit diagram: The OLED display is connected to the SCK and SDA pins of the Nano (A2 and A3 respectively), and powered by 5V and GND. The rotary switch encoder is connected as follows: VCC => 5V GND = > GND CLK => D9 DT => D8 SW => D2 My prototype board now looks like this: The updated code for driving the knob and display is available in  heater-with-display.ino in the Github repository . We now have a fairly compact (about 7cm x 5cm) and independent filament joiner (no need to connect to PC) that is driven solely by a 12V power supply. Here's how to use it to join printer filaments. More usage details in my previous post .

Adding "Stereo Mixer" to Windows 7 with Conexant sound card

This procedure worked for my laptop (Thinkpad E530) with a Conexant 20671 sound card, but I suspect it will work for other sound cards in the Conexant family. I was playing with CamStudio to do a video capture of a Flash-based cartoon so that I can put it on the WDTV media player and play it on the big screen in the living room for my kids. The video capture worked brilliantly, but to do a sound capture, I needed to do some hacking. Apparently, there was this recording device called "Stereo Mixer" that was pretty standard in the Windows XP days. This allowed you to capture whatever was played to the speaker in all its digital glory. Then under pressure from various organizations on the dark side of the force, Microsoft and soundcard makers starting disabling this wonderful feature from Windows Vista onwards. So after much Googling around, I found out that for most sound cards, the hardware feature is still there, just not enabled on the software side. Unfortunately, to