Convert Brady BMP 21 Held Printer to 18650 Lithium Batteries

Are you tired of buying batteries for your handheld label printer and disposing them in a few days?

Here is a simple way to convert the Brady BMP 21 to a pair of 18650 lithium batteries so you can charge them for free.

The consumption of the printer is around 7.4V. This voltage corresponds exactly to 2 x 18650 cells in series. You can find many battery holders providing the required setup for prices less than $2.

This setup with 18650 cells can provide longer cycle usage of the printer and give you the option to charge the batteries once they are empty using standard chargers for lithium batteries. You need to be very careful when working with lithium cells.

They store a lot of energy, and you can easily start a fire if you are not following standard safety rules and precautions. Lithium Polymer and Li-ion batteries are volatile.

Failure to follow the below instructions may result in fire, personal injury, and damage to property if charged or used improperly.

Parts

• Battery holder for 18650 for 2 cells
• 2 x 18650 cells.
• 2 x Wires.

Tools

• Soldering iron and solder wire
• Cutter Knife
• Claws or Pliers

Use a sharp knife or cutter to remove the bottom side of the battery holder. The holder's height needs to be less than 18mm so it can fit in the battery bay of the printer.

Solder the positive end of the cable of the 18650 holder to the spring on the right side of the battery bay in the printer. Solder the ground cable to the left side spring on the bottom of the printer. Insert 18650 cells into the holder. Make sure that they are connected in series.

Remove parts of the frame from the battery cover of the printer. This will allow two 18650 cells to fit inside, and you will be able to close the battery cover without issues.

Insert the holder into the battery bay of the printer. Make sure that the wires are not tangled, and close the battery bay. Turn the device ON and start printing.