ESP8266 Community Forum

Hi there!

I have a Wemos D1 Mini with an NTC and voltage divider. I have elaborate code that runs fine when the Wemos is stand alone and attached to my PC's USB. I also have a battery shield attached to a 3,7 LiPo battery. Whenever I hook this up to the Wemos D1 I observe the following behavior.

- First boot goes fine.
- After a few seconds I do a reset or interrupt the power and then the boot fails with:

I have tripple checked the solderings and tried pulling Hi GPIO0 and GPIO2, this aside from GPIO15 which I pulled low already.
I have used different sets of hardware, to no avail.

Please see attached a schema and a picture for reference.

Green wire is pulling GPIO15 low
Battery + is connected to shield out of view via underside of shield, minus can be seen
Purple wires is NTC.

Any suggestions would be very much appreciated.

I suspect the initial boot up current draw is pulling your LiPo voltage too low.

Put a big fat capacitor in there as a buffer for the initial spike and see how you go

Hi Davy,
Thanks, that sounds like something for me to explore. However, and I didn't mention this earlier: When i connect the ESP to USB/PC and I hook up the battery shield; i get the same erroneous behavior.

on your suggestion & as I am not an electronics guy by education; You are referring to a capacitor over input from battery into batt. shield, right? any suggestions on size (F)? Will investigate myself as well

Thanks a lot!

davydnorris wrote:I suspect the initial boot up current draw is pulling your LiPo voltage too low.
Put a big fat capacitor in there as a buffer for the initial spike and see how you go

Why repeated mentions of GPIO15? Its GPIO0 that controls booting or flashing. Yes 15 is involved and needs to be at the correct level too, but I have never know anybody have any problems with gpio15 when leaving it alone.

Google "ESP8266 boot pins" and make sure you are fully aware of the function of each.