How to Choose a USB-C Battery for Your ASP Flashlight
By Training Videos | UsingASPBatons | asp-usa.com | Published: 2026-10-22
Category: How-to Guides
Learn how to choose the right USB-C rechargeable battery for your ASP flashlight, with practical decision rules and trade-offs.
Quick Answer
Choose the ASP 10900 USB-C battery for compact ASP flashlights and the 21700 USB-C battery for high-drain models that need longer runtime. Match the battery size to your flashlight's specifications and prioritize PCM protection for safety.
Why Battery Size Matters
The physical size of the battery determines whether it fits your ASP flashlight. The 10900 and 21700 designations refer to the battery's dimensions in millimeters. Using the wrong size can damage the flashlight or prevent it from functioning.
Always check your flashlight's manual or the battery compartment for the required battery type. If you're unsure, contact the manufacturer or consult the product specifications before purchasing.
Safety Features to Look For
Lithium-ion batteries can be dangerous if overcharged or over-discharged. Look for a Protection Circuit Module (PCM) or similar safety circuitry. ASP batteries include PCM to guard against excessive charge/discharge cycles, which is essential for safe daily use.
The integrated USB-C port simplifies charging, but you still need to use a compatible charger and follow the manufacturer's guidelines to avoid damage.
Trade-offs: Capacity vs. Size
The 21700 battery is physically larger, which typically means higher energy density and longer runtime. However, it only fits flashlights designed for that size. The 10900 is more compact and may be the only option for smaller lights.
Consider your typical use: if you need all-day runtime for duty or extended outdoor use, the 21700 is often the better choice. For everyday carry or shorter tasks, the 10900 may be sufficient.
Decision Rules for Choosing Your Battery
- Check flashlight compatibility: Look for the battery size (10900 or 21700) in your flashlight's manual or inside the battery compartment. Only buy a battery that matches that size. If the size isn't listed, contact the manufacturer before buying.
- Assess your runtime needs: If you use your flashlight for long shifts or extended outdoor activities, choose the 21700 for its higher energy density. For occasional or short use, the 10900 is adequate. Consider carrying a spare battery for extra-long tasks.
- Prioritize safety features: Ensure the battery has a Protection Circuit Module (PCM) to prevent overcharging and over-discharging. Both ASP options include this feature. Never use a battery without PCM in high-drain devices.
- Consider charging convenience: Both batteries feature an integrated USB-C port, so you can charge them directly without a separate charger. This simplifies charging on the go. Keep a USB-C cable handy for quick top-ups.
Product Facts
- ASP Lithium Ion 10900 USB-C Battery & Link Case: ASP lithium-Ion rechargeable batteries are custom-fabricated for increased energy density and longer life, and feature a PCM protection circuit. This means you get reliable power and safety against overcharging, making it a solid choice for compact ASP flashlights.
ASP Lithium Ion 10900 USB-C Battery & Link Case - NEW 21700 USB-C Battery & Link Case: The 21700 battery is optimized for high-drain devices and includes a Protection Circuit Module for safety. It's designed for flashlights that demand more power, so you can expect consistent performance during extended use.
NEW 21700 USB-C Battery & Link Case
Who Should Choose Which
Best for
- The 10900 USB-C battery is best for compact ASP flashlights used for everyday carry or short tasks.
- The 21700 USB-C battery is best for high-drain ASP flashlights used for duty, security, or extended outdoor activities.
Not for
- The 21700 battery is not for flashlights that only accept the smaller 10900 size.
- The 10900 battery is not for high-drain flashlights that require the larger 21700 for adequate runtime.
