The compact TS457 portable internal resistance tester box, powered by a USB cable, is economical, affordable, and easy to use! The accessory model will be sent later (it was printed a long time ago using an old printer; the precision isn’t great, as everything was manually scaled up, and I’ll re-print and send it after making some adjustments).

Manufacturing process

Find a female USB connector and a 4-pin XH2.54 terminal block, then solder them together with a soldering iron, as shown in the picture (the four USB wires happen to serve as leads for the two probes).

The TS457 wiring is as shown in the diagram:

Connect the two wires together, paying close attention to the wire order (check the colors!!!), paying close attention to the wire order (check the colors!!!), paying close attention to the wire order (check the colors!!!).

Next, add two battery cells.

Insert them into the corresponding positions in the box, with the negative terminals connected to the springs.

After completion

Bend the back side upward and secure it.

The overall wiring diagram shows that a 4.2V charger is also connected. Since the connections are secured with hot-melt adhesive, any charger port of roughly the same size will work.

Place the module and accessories in their respective positions. There are also two wires that connect to the boat-shaped switch; I didn’t take detailed photos of this part, but I’m sure everyone can handle it without any issues.

Zoom in for a closer look

Heat the hot-melt adhesive to secure everything; if anything feels loose, add more adhesive.

Completion