18350 Batteries

18350 Batteries: Small Size, Serious Output

18350 batteries are rechargeable lithium‑ion cells measuring approximately 18 mm in diameter by 35 mm in length. With a nominal voltage of 3.6–3.7V and typical capacities of 700–1200 mAh, they enable compact lights and electronics to deliver high output for short to moderate runtimes. They are not universal replacements for CR123A primaries (3.0V) unless the device explicitly supports 3.7V rechargeable cells.

How to Choose an 18350

1) Capacity vs. Discharge Rating

• Capacity: ~700–1200 mAh. Higher capacity = longer runtime but often slightly lower maximum discharge rate.
• Discharge (CDR): Look for 6–10A CDR for high‑output flashlights; 10–15A cells exist but usually with lower capacity.
• Use higher‑capacity cells for medium modes; choose higher‑drain cells for turbo/peak brightness.

2) Protected vs. Unprotected

• Protected: Adds an internal protection circuit (over‑charge/over‑discharge/short protection). Slightly longer (often 37–39 mm) and wider; best for general users and devices without built‑in protections.
• Unprotected: Standard length (~35 mm). Favored for high‑drain and tight‑fit lights that rely on the device’s low‑voltage cut‑off. Requires careful handling.

3) Button‑Top vs. Flat‑Top

• Button‑top: Raised positive terminal; improves contact in many flashlights and some optics.
• Flat‑top: Flush positive terminal; common for multi‑cell packs or lights designed for flat tops. Check your device’s requirement.

4) Chemistry and Voltage

• Li‑ion (3.6–3.7V nominal, 4.2V full): Most common for flashlights and compact electronics.
• LiFePO4 18350 (3.2V nominal, ~3.6V full) also exist for devices requiring lower voltage; capacity is usually lower.

5) Size Tolerances

• Actual dimensions vary by brand and protection board. If your device is tight, confirm max length/diameter before buying.

Expected Runtime (Examples)

Approximate continuous runtimes assuming efficient drivers; real results vary by light, mode, and thermal step‑downs.

Current Draw	800 mAh cell	1000 mAh cell
0.7A (≈300 lm)	60–70 min	80–90 min
1.5A (≈600–700 lm)	30–35 min	40–45 min
3A (≈1000+ lm burst)	12–20 min	18–25 min

When to Choose vs. Avoid

• Choose 18350 if you need: smallest form factor, pocket EDC lights, short high‑output bursts, backup power for compact optics or sensors.
• Avoid 18350 if you need: long runtimes, cold‑weather endurance, or all‑day duty use—consider 18650 or 21700 instead.

Compatibility Notes

• Not a direct replacement for CR123A (3.0V). Only use if your device lists 18350 or 3.7V Li‑ion compatibility.
• Devices designed for two CR123A cells (≈6V total) typically do not accept a single 18350. Some flashlights offer dedicated 18350 tubes—use only as specified.
• Button/flat top and cell length affect fit; check your device’s contact design and length allowance.

Charging and Care

• Use a quality Li‑ion charger with 18350 support. Recommended charge rate: 0.3–0.6A (≈0.3–0.6C). Faster charging shortens cycle life.
• Typical charge time: about 2–2.5 hours for 900–1000 mAh at 0.5A.
• Storage: cool, dry place at ~40–60% charge. Top up every 3–6 months.
• Cycle life: often 300–500 full cycles when used and charged conservatively.
• Safety: never carry loose cells—use a case. Do not mix old/new cells or brands. Do not use in series unless the device is designed for it.

18350 vs. Alternatives

• 16340 (RCR123A): Slightly smaller; often 500–800 mAh. May fit where 18350 does not. Shorter runtime than most 18350s.
• 18650: Much larger; 2600–3600 mAh. Best for long runtimes; increases device size.
• CR123A primary: 3.0V disposable; long shelf life for emergency use; not rechargeable and different voltage.

Use Cases

• EDC and tactical flashlights with optional 18350 tubes
• Compact weapon lights and optics rated for 3.7V rechargeables
• Sensors, small handheld instruments, and custom electronics

Pros and Cons

• Pros: very compact; supports high output; lightweight; rechargeable convenience.
• Cons: shorter runtime than 18650/21700; fit varies by brand; requires compatible device and proper charger.

FAQ

Can I use an 18350 in a device that takes CR123A?

Only if the device manual states compatibility with 3.6–3.7V rechargeable cells (18350/16340). Many CR123A‑only devices are not safe for Li‑ion.

Should I buy protected or unprotected?

Choose protected for general safety, especially if your device lacks low‑voltage protection. Choose unprotected for tight fits or high‑drain performance when the device has proper safeguards.

Button‑top or flat‑top?

Many flashlights prefer button‑tops for reliable contact. Some compact lights and carriers require flat‑tops. Check the product specs.

How long will an 18350 last per charge?

Expect 15–90 minutes depending on output level. High‑drain turbo modes can exhaust a cell in under 20 minutes; medium modes often deliver 45–90 minutes.

What’s the safe way to charge?

Use a Li‑ion charger set to 4.2V with a 0.3–0.6A current. Stop using any cell that gets abnormally hot, is swollen, or has damaged wrapping.