EV3 Switching to Rechargeable Batteries

The idea of the project is to get rid of the batteries for EV3 block and power it from the Li-Ion rechageable batteries. Also to remain the possibility return to the original state.

Supplies

2 Li-Ion 18650

Power jack connectors, piece of perforated soldering board

Charging controller TP4056

DC-DC step-up converter MT3608

Plastic for the new cover

Old USB cable and black and red wires

Step 1: Making the Cover

The hardest part of the project is to make the new cover, the old one does not permit using 18650 elements. I used the plastic from the old HP inc jet printer. Cutted the suitable pieces and glued it together with cyanopan as displayed. The latches displayed at the left side were cutted of from the front panel of my old CD-ROM. The latches from the right side were made similar by shape and size to the original cover and enforsed from inside with 2 pieces of plastic. Not perfect but it works.

If you could find the suitable Li-Ion you might fit it with the controller and convertor under the original cover.

Step 2: Wiring

The module TP4056 has the markers for soldering the wires for input DC power, battery, and output DC. Each pin has +/- markers thus it fairly easy to use. Connect output of TP4056 to step up DC-Dc converter MT3608. The otput of step up converter connected by two wires to small nikel strips formed as U shape for elasticity, to the EV3 power input.

The power cable for charging made from the old USB cable. Check the polarity by voltmeter before and after soldering.
Close cover and turn on.