The CR123 vs. 18650: Why Your Go-Bag Flashlight Needs a Rechargeable System

Photo by Roman Dolgikh on Unsplash

It’s 0300. You hear a sound that doesn’t belong—a crash in the kitchen or the unmistakable sound of a car door closing softly outside. You reach for your “trusted” tactical flashlight, the one you spent $150 on. You hit the switch and get… a dim, yellowy, pathetic beam.

Why? Because you’ve been “saving” the batteries.

You’ve been babying that light, using it on low, or worse, using your phone for everyday tasks because you didn’t want to burn through that four-pack of CR123As that costs $15.

As members of the military, law enforcement, or just prepared citizens, we obsess over lumens, candela, bezel design, and IPX-8 waterproof ratings. But we consistently ignore the single most critical component of our illumination tools: power logistics.

For years, the CR123A lithium primary battery was the undisputed tactical standard, largely thanks to its 10-year shelf life. I’m here to tell you that for 99% of us, that era is over. Your primary, “go-to” flashlight, and especially your go-bag light, must be built around a modern rechargeable battery system.

Here’s the no-BS breakdown.

The “Old Guard”: The Case For (and Against) the CR123

To be clear, the CR123A still has a place. Let’s give it its due.

The Pros:

• Shelf Life: 10+ years. You can vacuum-seal them and toss them in a cache or a deep-storage medical kit and know they’ll work a decade from now.
• Temperature Tolerance: They have a slight edge in extreme, sub-zero cold, retaining their voltage better than some Li-ion cells.

That’s it. That’s the list. Now, here’s why they fail as a primary power source.

The Cons:

1. The Cost Sink: They are brutally expensive. A single set can be $6-$10. This creates “training anxiety”—a subconscious (or conscious) reluctance to use your damn gear. You end up with a high-speed light that you’re afraid to turn on.
2. The Power Bottleneck: This is the critical technical failure. Modern LEDs are power-hungry. That 2,500-lumen “Turbo” mode on your new light? A pair of CR123s simply cannot provide the high, continuous voltage required to run it. The light will either not hit its advertised brightness or will step down almost immediately. You’ve bought a Ferrari and put watered-down gas in the tank.
3. The Logistical Nightmare: When they are dead, they are dead. They are a finite resource. In any real-world “grid-down” or long-term field scenario, you are carrying a brick. Your supply is only as large as your pack.

The New Standard: The Rechargeable “Power System” (18650 & 21700)

When I say “rechargeable,” I’m not talking about the weak AA NiMH cells in your TV remote. I’m talking about high-drain, lithium-ion (Li-ion) “power cells” like the 18650 (the former standard, still excellent) and the 21700 (the new king).

These cells are a fundamental shift in capability.

Benefit 1: Raw, Uncompromising Performance

A high-drain 21700 or 18650 is a power plant. It is designed to dump high voltage on demand. This is the only way to get those insane 3,000-lumen turbo modes and, more importantly, to sustain a high-output (1,000+ lumen) beam for more than a few minutes without a massive drop-off. It unlocks the full performance you paid for.

Benefit 2: The “Logistics-Proof” Ecosystem

This is the most important point for any Havok Journal reader. A rechargeable system makes you logistically independent.

You are no longer a consumer of batteries; you are a manager of your own power.

With just two or three spare rechargeable cells and a small USB-C charger, you have a virtually infinite supply of light. You can charge your rechargeable batteries from:

• Your vehicle’s USB port.
• A solar panel on your go-bag.
• A portable power bank.
• Any wall outlet.

This capability is a tactical game-changer. It means you can use your light every single night. You can run low-light drills, clear your property, or scan the woodline—all on full power—and know that you’ll be at 100% again by morning. The cost is zero. You have removed “training anxiety.”

Benefit 3: The Cost Analysis

A top-tier 21700 battery and a simple USB charger will cost you about $30-$40. That is the equivalent of 4-5 sets of CR123s. You will make your money back in one decent weekend of low-light training. After that, your light is effectively free to run.

What “System” to Buy: Don’t Buy a Light, Buy a Platform

Start thinking of your light as part of a power platform.

• For New Purchases: Go with a 21700-platform light. This is the new standard, offering the best balance of high capacity and size. Many new cells even have a USB-C port built right into the battery, meaning you don’t even need a separate charger.
• For Weapon Lights (WMLs): This is the one area CR123s have held on. However, the most high-performance WMLs from companies like Modlite and Cloud Defensive are built around 18650s and 21700s. Why? Because candela (beam intensity/throw) requires power that only these cells can provide.
• For EDC: Many small EDC lights now use a 16340 (or RCR123). This is a rechargeable cell with the exact same size as a CR123A. It gives you the best of both worlds: compact size and reusability.

Your “Ready” Light vs. Your “Stashed” Light

Here is your final, actionable plan. It’s not one-or-the-other; it’s “right tool for the right job.”

1. Your “READY” Light: This is your primary light. It’s on your nightstand, in your pocket, or on your go-bag. This light MUST run on a rechargeable battery system (21700, 18650, or 16340). You need it to be fully capable, all the time, and you need to be able to train with it fearlessly.
2. Your “STASHED” Light: This is your deep-storage, “end-of-the-world” backup. It’s vacuum-sealed in your vehicle kit or at the bottom of a medical bag. This is the light you load with fresh, 10-year-shelf-life CR123As.

Stop being a gear collector who is afraid to scratch his tools. Be an operator. Your life-saving equipment demands a power source you can depend on, sustain, and—most importantly—train with. Give your light the fuel it deserves.