DIY Upgrade a Surpeer AV4 Multimeter to Lithium Power

If you simply add a small metal contact plate to your Surpeer AV4 4½-digit digital multimeter and convert it to lithium battery power, you will no longer need to replace 9V batteries so frequently. Tests have shown that even a single lithium battery can power this multimeter, but its limited capacity results in relatively short battery life. The battery compartment has just enough room to accommodate two 14500 batteries. The only thing missing is a small metal contact plate for the battery connection.

First, use a caliper to measure the width of the metal plate.

These are two 14500 batteries.

Confirm that the metal plate width is 22 mm.

To fit the battery compartment, you can cut a notch in the middle of the metal plate to make installation easier.

Next, bend the metal plate into shape, then cut it in half from the middle.

The two batteries fit perfectly inside the battery compartment. Install the contacts and connect the circuit.

Power on the multimeter. Everything works normally. Modification complete.