3.7V 500mAh Li-ion RC Battery 2-Pack with USB Charger - Reliable

In this review the Blomiky 3.7V 500mAh Li-ion battery 2-pack is examined as a low-cost replacement for small RC cars, boats and stunt vehicles; the single biggest reason to buy is straightforward: these batteries deliver the correct 3.7V form factor, an SM-2P black 2-pin plug and a built-in USB charge cable with over-charge protection so users can replace worn cells and get back on the track quickly. The reviewer tested fit, charging behaviour and day-to-day usability to see whether these spare batteries are a practical swap for common 1/18 and similar small-scale RC models.

Key Features

• Real capacity: The batteries report a real capacity range of 500mAh to 800mAh which provides usable runtime for many small RC cars and boats before needing a recharge.
• Standard connector: The SM-2P black 2-pin plug with a roughly 5.5 x 5.2mm cross-section matches many toy-grade RC wiring harnesses so installation is typically tool-free.
• Compact size: At 51 x 18 x 14mm the battery fits into small chassis compartments designed for 1S 3.7V packs without major modification.
• Built-in USB charging: Each charge cable has an over-charge protection board and a charging indicator so users can plug into any USB port and safely charge the pack.
• Lightweight spare: Weighing about 19g per cell, these packs add minimal weight to small stunt cars and amphibious boats, preserving handling and performance.

Who It's For

These batteries are best for hobbyists and casual owners of small remote control vehicles who need an inexpensive, ready-to-use spare that matches 3.7V 1S form factors and the SM-2P plug. They suit owners of 1/18 and some 1/16 scale stunt cars, small RC boats, amphibious stunt vehicles and toy-grade models from brands that use similar size and connector standards.

Those who should look elsewhere include users of larger or professional RC models that require higher capacity or different connector types, and anyone who cannot confirm the exact voltage, plug type and physical dimensions of their original pack before buying.

Pros & Cons

Pros

• Good value 2-pack with two charge cables included, which makes replacing multiple batteries convenient.
• Built-in USB charger with an over-charge protection board stops charging near 4.2V and shows a red charge indicator light.
• Compact dimensions and light weight make them easy to fit into many small RC vehicles.

Cons

• Quality impressions vary slightly among users, so performance and longevity may differ between individual packs.

Specifications

Battery chemistry	Li-ion (1S)
Nominal voltage	3.7V
Rated capacity	500mAh (real 500mAh-800mAh)
Connector	SM-2P black 2-pin (5.5 x 5.2mm cross-section)
Dimensions	51 x 18 x 14mm (2.0 x 0.72 x 0.56 in)
Weight	19g (0.66 oz) per battery
Included	2 batteries and 2 USB charge cables with over-charge protection

Our Verdict

The Blomiky 3.7V 500mAh 2-pack is a practical, low-cost replacement for owners of small stunt cars and boats that use the SM-2P 1S battery format; it includes USB charge cables with over-charge protection and a clear charge indicator, making it an easy swap for hobbyists who need spares. For the price it delivers solid functionality and value, though buyers should confirm plug, voltage and size match their vehicle before ordering.

Frequently Asked Questions

How long does a full charge take?
Charging typically takes about 2-4 hours using the included USB charge cable depending on the power source.

Will these batteries fit my stunt car?
They fit many 1S small RC cars and boats that use a 3.7V pack and an SM-2P connector, but you must confirm the voltage, plug type and 51 x 18 x 14mm dimensions first.

Does the charger stop when full?
Yes, the built-in over-charge protection stops charging near 4.2V; the red indicator light turns off when fully charged or after reconnecting if it remains on.