Tiny Battery Level Indicator – 1S LiPo / Li-ion (4-LED)

Please note: this is a very, very small component, about 9.5 × 5 mm, smaller than your fingernail. Check the fingertip photo for scale before you order.

That tiny size is the point. Connect it straight across a single-cell 3.7V LiPo or Li-ion battery and it shows how much charge is left on four little LEDs (red, yellow, green, green). There's no microcontroller and no code — just two connections. It's small enough to peek through a buttonhole, sit behind a sheer panel, or tuck into the lining of a bag, so you know when it's time to recharge.

Specifications

• Battery type: 1S (single cell) 3.7V LiPo / Li-ion, 4.2V fully charged
• Display: 4 LEDs — 25% / 50% / 75% / 100%
• Approximate thresholds: 25% 3.40–3.55V · 50% 3.55–3.70V · 75% 3.70–3.87V · 100% 3.87–4.20V
• Size: about 9.5 × 5 mm
• Connection: 2 (+ and −)
• No programming required

Pin Definitions

• + — Battery positive
• − — Battery negative

Project Ideas

A charge gauge on a light-up handbag, a hidden battery check inside a costume, a status window on a wearable enclosure, or a quick battery checker for your workbench.

Good to know

The indicator draws a small current whenever it's connected. For long-term projects, add a small push button or switch so it only lights up when you check it. It's for single-cell (3.7V) batteries only: don't connect it to 2S packs, 5V USB or coin cells.

Pair It With

Use it with our Lithium Battery Charging Board to build a rechargeable power setup. Powering LEDs like the 16-LED RGB ring? This tells you when to top up. Use our soft silicone wire sampler to route it somewhere visible.

In the box

• 1S battery level indicator × 1