3pcs Wemos® Battery Shield V1.2.0 For Wemos D1 Mini Single Lithium Battery Charging & Boost Module
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Very good indeed. I'll be using these on lots of projects, not just D1. Should power a Pi Zero quite well too, though I've not checked that. For use with D1, I chose to solder the long pin-sockets from the D1 kit into the charger board, then the D1 sits on top using normal pins, this keeps the antenna clear and works nicely in breadboard.
Nice and handy to power your IOT projects. Shame there isn't and on/off switch. However it's not impossilbe to add your own. Having the ability to direct wire the bat positive to the A1 pin of the mini D1 makes it really handy to add a battery level meter to monitor the battery status. For the price a excellent addition to the Mini D1 ESP2866. Handy bit of kit.