Compact Field Battery Voltage Tester for Airsoft LiPo/Li-Ion Packs

A compact and lightweight inline voltage tester designed for quick battery checks directly on the field. Originally made for Airsoft replica batteries, but compatible with many other battery chemistries and applications.

The tester uses a standard 3-digit digital voltmeter module mounted inside a simple 2-piece 3D printed enclosure. It allows fast verification of battery charge status without requiring a charger or larger bench equipment.

The voltmeter supports approximately 3V up to over 24V, making it suitable for:

• LiPo packs

• Li-Ion packs

• NiMH packs

• Lead-acid batteries

• Other DC battery systems within range

The current build uses T/Deans connectors, but any connector type can be soldered depending on your needs.

Wiring

The voltmeter has:

• 1 black wire (negative)

• 2 positive wires (red and yellow)

The red and yellow wires must be soldered together to the positive terminal:

• one powers the voltmeter electronics

• the other measures the input voltage

The black wire goes to battery negative/common ground.

I replaced the original thin wires with thicker wires for better durability and lower resistance.

Construction

The enclosure consists of:

• 2 printed parts

• secured with 2× M2x12 mm self-tapping screws

The voltmeter sits tightly inside the case.

Printing

Printed in PLA successfully, although:

• PETG is recommended for better temperature resistance

• ASA is better for outdoor durability and heat resistance

Notes

• Simple and inexpensive project

• No calibration required in most cases

• Useful as a permanent toolbox accessory or quick field diagnostic tool

• Compact enough to fit in an Airsoft gear pouch or pocket