WeMos D1 Mini Lithium Battery Shield (HCWEMO0009)

[admin]

The Wemos lithium battery shield provides a means of powering your Wemos mini, or Wemos mini Pro (see item HCWEMO0002) from a single cell (3.7V) lithium battery. The shield contains a DC-DC converter to step-up the batteries 3.7V to 5V supplying your Wemos mini and shields with up to 1A of power. When the battery is depleted simply plug the shield into a USB power source using a mini USB cable and it will automatically recharge the battery. Two LEDs on the shield indicate when the battery is charging and when charging has completed.



Features

Charging Voltage: max: 10V, recommend: 5V
Charging Current: max: 1A
Lithium Battery voltage: 3.3-4.2V
Boost Power Supply: 5V(max: 1A)



Pins

D1 mini	Shield
5V		Power Supply, 5V(max: 1A)
GND		GND

Ports

PH2-2.0MM (Port 1)	Connect to lithium Battery (normal 3.3-4.2V)
Micro USB (Port 2)	Charging port (normal 5V)
Green LED			lights when charging is completed
Red LED			lights when charging
J1				setting max charging current, 0.5A or 1A.
J2				Connect battery to A0

Schematic:

sch_battery_v1.3.0.pdf

Libraries, example code, and diagrams are provided as an additional free service by Hobby Components and are not sold as part of this product. We do not provide any guarantees or warranties as to their accuracy or fitness for purpose.

Descriptions and diagrams on this page are copyright Hobby Components Ltd and may not be reproduced without permission.

[gadjet]

Hi,
Do you know if this acts like a backup battery so if I power the D1 from the USB connector it provides 5 V to the D1 and charges the connected battery at the same time and if I remove the USB power it still provides 5V to the D1 from the connected Battery?

[andrew]

Yes that is correct. Whilst the USB cable is connected both the battery will be charged, and 5V will be supplied to the 5V pin (~4.5V). If the USB cable is disconnected 5V will continue to be applied to the 5V pin (~5V) whilst the connected battery holds a charge.

[gadjet]

Thanks, just what I thought.

[wavedebb]

Would it charge the battery from the 5v line if the usb was plugged into a D1 mini for instance?

[andrew]

Would it charge the battery from the 5v line if the usb was plugged into a D1 mini for instance?

No, I'm afraid to charge the battery it must be powered via the battery shields USB port.

[bravenius]

Hi All,

Maybe everyone know (evident from schematic) that this circuit don't prevent under discharge, the direct path from +B thru inductor & diode, allow battery to go ~1V, damaging the cell. is recommended a BM board in the cell. Quite bad design and also this board don't allow signaling low battery to uC. Datasheet indicates:

Automatic frequency adjustment, adapts to different output loads (5v output no-load current is less than 10uA). Output auto cutoff when battery voltage is low (Vbat < 3.0v)

this cant be implemented as far as I understand. (I have empiric example of battery damage on few cycles... so this can't work).