Understanding Torch Batteries: Complete Guide

The battery in your torch is arguably the most important component after the LED itself. It determines how bright your torch can shine, how long it will run, and how reliably it will perform when you need it. Yet batteries remain one of the most misunderstood aspects of torch ownership.

This guide demystifies torch batteries, covering everything from basic battery types to advanced topics like discharge rates and proper charging practices. Whether you're new to rechargeable torches or looking to optimise your existing setup, you'll find practical, actionable information here.

Battery Types Overview

Modern torches use a variety of battery types, each with distinct characteristics. Understanding these differences helps you choose the right torch and get the most from your investment.

Lithium-Ion Rechargeable Batteries

The most popular choice for high-performance torches, lithium-ion cells offer the best combination of capacity, power delivery, and rechargeability.

18650 Batteries

Named for their dimensions (18mm diameter, 65mm length), 18650 cells are the workhorse of the torch world. They offer excellent capacity (typically 2500-3600mAh), good power delivery, and widespread availability.

• Capacity: 2500-3600mAh typical
• Voltage: 3.6-3.7V nominal
• Best for: Compact to mid-sized torches, headlamps, EDC lights
• Lifespan: 300-500 charge cycles typical

21700 Batteries

The larger 21700 format (21mm x 70mm) is increasingly popular in high-performance torches. They offer more capacity than 18650s while fitting in only slightly larger torch bodies.

• Capacity: 4000-5000mAh typical
• Voltage: 3.6-3.7V nominal
• Best for: High-output torches, extended runtime needs
• Advantage: 30-40% more capacity than 18650s

Other Lithium-Ion Sizes

• 14500: AA-sized lithium rechargeable. Higher voltage than AA, check torch compatibility.
• 16340/RCR123A: Rechargeable equivalent of CR123A primary cells.
• 26650: Large format for maximum capacity, less common in mainstream torches.

Primary (Non-Rechargeable) Batteries

Primary cells remain relevant for specific applications, particularly emergency preparedness and situations where charging isn't practical.

CR123A

A favourite for tactical and compact torches, CR123A cells deliver high power from a small package. They have excellent shelf life (up to 10 years) but higher ongoing costs.

• Voltage: 3V
• Capacity: ~1500mAh
• Best for: Emergency backup, extreme temperature use
• Note: Can be expensive; consider rechargeable 16340 alternatives for regular use

AA and AAA Batteries

Standard disposable batteries remain popular for their universal availability. You can buy them anywhere, making them ideal for travel or emergency situations.

• Lithium (L91/L92): Best performance, wide temperature range, lightweight
• Alkaline: Cheapest option, reduced performance in high-drain devices
• NiMH Rechargeable: Environmentally friendly, good for moderate use

Understanding Battery Specifications

Capacity (mAh)

Measured in milliamp-hours (mAh), capacity indicates how much energy a battery stores. Higher mAh means longer runtime, but real-world performance depends on many factors.

Discharge Rate

High-output torches demand significant power quickly. Discharge rate, measured in amps (A) or as a C-rating, indicates how quickly a battery can safely deliver its energy.

• Low-drain (5A or less): Suitable for standard torches, longer life
• Medium-drain (10-15A): Good all-round choice for most users
• High-drain (20A+): Required for high-output tactical torches

Protected vs Unprotected Cells

Protected batteries include a small circuit board that prevents over-discharge, over-charge, and short circuits. Unprotected cells lack these safeguards.

• Protected: Safer, recommended for most users, slightly longer and heavier
• Unprotected: Required for some high-drain applications, demands user knowledge

For beginners, protected cells provide peace of mind. Many quality torches also include built-in protection, allowing safe use of unprotected cells—check your torch's specifications.

Charging Best Practices

Choosing a Charger

A quality charger is as important as quality batteries. Look for these features:

• Individual cell monitoring: Each bay charges independently based on the cell's needs
• Automatic termination: Stops charging when complete, preventing overcharge
• Multi-chemistry support: Handles Li-ion, NiMH, and other types correctly
• Status display: Shows charge progress, voltage, and any issues
• Adjustable charge rate: Slower charging extends battery life

Charging Guidelines

Follow these practices for optimal battery health and safety:

• Charge at room temperature (15-25°C is ideal)
• Never charge immediately after heavy use—let batteries cool first
• Use the charger's lower current setting when time permits
• Remove batteries promptly after charging completes
• Never leave charging batteries unattended overnight
• Charge on non-flammable surfaces away from flammable materials

Storage Recommendations

Short-Term Storage (Days to Weeks)

For batteries in regular rotation:

• Store at room temperature in a dry location
• Keep away from metal objects that could cause shorts
• Use a battery case or organiser
• Maintain reasonable charge level (40-80%)

Long-Term Storage (Months to Years)

For seasonal equipment or backup batteries:

• Charge to approximately 40-60%
• Store in a cool location (10-20°C ideal)
• Check and top up charge every 3-6 months
• Keep in fireproof battery storage bag for extra safety
• Label with storage date to track age

Safety Considerations

Signs of Battery Problems

Immediately stop using any battery that shows:

• Swelling: The wrapper is bulging or the cell won't fit properly
• Physical damage: Dents, tears in wrapper, exposed metal
• Unusual heat: Getting hot during use or charging
• Odour: Chemical smell or visible venting
• Reduced capacity: Significant runtime decrease indicates age or damage

Safe Disposal

Lithium batteries should never go in regular rubbish. They can cause fires in waste collection and processing facilities. In Australia:

• Return to battery recycling points at Officeworks, Bunnings, and Aldi
• Many council waste facilities accept batteries
• Tape terminals before disposal to prevent shorts
• Never attempt to open, burn, or puncture batteries

Battery Recommendations by Use Case

Everyday Carry

A quality 18650 or built-in rechargeable suits most EDC needs. Look for USB-C rechargeable torches for maximum convenience.

Emergency Preparedness

Store both rechargeable batteries (for regular testing) and lithium primaries (for long shelf life). CR123A or lithium AA cells won't degrade over years of storage.

Heavy Outdoor Use

21700 batteries provide the best capacity-to-weight ratio for extended trips. Carry spare cells in a waterproof case.

Extreme Conditions

Lithium primary cells perform best in extreme cold. Some rechargeable cells are rated for extended temperature ranges—check specifications for cold-weather use.

Conclusion

Understanding batteries transforms torch ownership from a mystery into a straightforward matter of matching the right power source to your needs. Whether you opt for the convenience of built-in charging or the flexibility of replaceable cells, following proper care practices ensures reliable performance for years.

For help choosing a torch that matches your needs, try our interactive torch finder or read our beginner's guide to choosing your first torch.