HI fons and every one,
I am glad that the problem was resolved while I was sleeping!.
I would like to review a few things.
OK, mystery solved. I redid the battery pad soldering and the power consumption went down to a reasonable value. I triple checked it when I did it the first time, but my guess is the cables may have been touching the GPIO pin pads.
I actually suspected the wiring problem when I first saw the photos of fons soldering, but I decided that fons was experienced in electronics and didn’t point it out. I regret that. Here is a picture of my soldering for reference. I use thin leads and glue them in place so they don’t move.
However, that still doesn’t explain the difference when using the battery pads
I think the reason why the sleep current is 30uA when powered from the battery pad is due to the leakage current of the LMBR4010. According to the datasheet, it is 8uA at 25C, but it easily doubles if the temperature rises even slightly. There is also a large individual variation (confirmed with 3 pieces). If the current increases significantly when the can is warmed by warm air, I think the diode is the cause.
I started the experiment with a large load current because I saw the efficiency graph posted by fons and mistakenly thought that there was a problem with the efficiency at mA load. However, I am glad that I recognized the problem of heat generation in the ESP as a result.