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FindMyBattery

Search by size, use, capacity, discharge, and terminal type. Exact matches shown first — compatible suggestions when none exist.

Understanding rechargeable lithium batteries

Rechargeable lithium-ion batteries power flashlights, e-bikes, power tools, and DIY energy storage systems. Unlike single-use alkalines, these cells can be recharged hundreds to thousands of times — but they have specific requirements every user should understand before purchasing.

⚡ Always use a quality charger matched to your battery chemistry. Overcharging or using the wrong charger is the most common cause of battery failure and safety incidents.

Battery chemistry types

Li-ion / IMR: High energy density. Common in flashlights and electronics. Higher discharge rate, lighter weight. Nominal voltage: 3.6–4.2V.

LiFePO4 (LFP): Safer chemistry, longer cycle life (2,000–5,000 cycles), lower voltage (3.2V nominal). Used in solar storage and e-bikes.

NiMH: Nickel-Metal Hydride. AA/AAA format, 1.2V. Compatible with multi-chemistry chargers that support Li-ion and NiMH.

LiPo: Lithium Polymer. Flexible form factor, found in power banks. High energy density — handle with care to avoid puncture.

How to read a battery spec

When you see a spec like Samsung 30Q 18650 3000mAh 15A, here's how to decode each part:

Brand model (30Q): The manufacturer's model code. Q-series Samsung cells are optimized for high-drain use.

Size (18650): 18mm diameter × 65mm long × cylindrical (0). See the Size Reference tab for a full chart.

Capacity (3000mAh): Milliamp-hours — how much energy it stores. Higher mAh = longer runtime at the same current draw.

Max discharge (15A): Continuous Discharge Rating. Exceeding this causes heat buildup, reduced lifespan, and potential failure.

Flat top vs button top

Flat top batteries have a flush positive terminal. Button top batteries have a small raised nub. Most devices are engineered for one or the other — check your device's manual before purchasing. Items in this catalog clearly indicate "Button Top" or "Protected Button Top" in their name.

Protected vs unprotected

A protected battery contains a small PCB that prevents overcharge, over-discharge, and short circuits — a safety layer for casual users. Unprotected cells are slightly shorter and lighter, preferred for high-drain builds. For flashlights and general use, protected cells offer useful peace of mind.

Capacity vs discharge: the tradeoff

Cell	Capacity	Max CDR	Best for
Samsung 35E	3500mAh	8A	Long runtime, low-drain devices
Samsung 30Q	3000mAh	15A	Balanced — flashlights, general use
Samsung 25S	2500mAh	25A	Moderate high-drain
Samsung 20S	2000mAh	30A	High-drain applications
Molicel P50B	5000mAh	60A	Best of both worlds (21700)
EVE 50PL	5000mAh	125A	Extreme drain (21700)

USB-C rechargeable cells

Some Nitecore cells (NL1836R, NL2140R, etc.) have a built-in USB-C port, charging directly without a separate charger. Use the "USB-C Rechargeable" toggle in the finder to see these options.

Battery wraps & safety

The colored PVC sleeve on a cylindrical battery provides electrical insulation. A torn, nicked, or peeling wrap is a safety hazard and must be replaced before use.

How battery size codes work

The number code encodes the cell's physical dimensions. First two digits = diameter (mm), next two = length (mm), last digit = shape (0 = cylindrical). Example: 18650 = 18mm wide × 65mm long × cylindrical.

Size	Ø	Length	Also known as	Common uses	Catalog examples
14500	14mm	50mm	AA Li-ion	Compact flashlights, devices upgraded from AA	Efest 14500, XTAR 14500, Nitecore NL1410
16340	16mm	34mm	RCR123A	Compact flashlights, gun lights, cameras	Efest 16340, XTAR 16340, Nitecore NL169
18350	18mm	35mm	—	Compact devices, half-length 18650 alternative	Efest 18350, MXJO 18350, Nitecore NL18350A
18500	18mm	50mm	—	Mid-length flashlights, between 18350 and 18650	Efest 18500, MXJO 18500
18650	18mm	65mm	—	Most popular worldwide: flashlights, laptops, DIY packs	Samsung 30Q, Molicel P30B, Panasonic NCR18650B, 100+ more
20700	20mm	70mm	—	High-capacity devices, power tools	Efest 20700, Sanyo NCR20700B, Hohm Sherlock V2
21700	21mm	70mm	—	EVs, power tools, high-performance lights, DIY packs	Samsung 50S, Molicel P45B, EVE 50PL
26650	26mm	65mm	—	Large-format flashlights, high-capacity builds	Efest 26650, MXJO 26650, Hohm Grown, XTAR 26650

🔍 Quick check: If your device currently uses a CR123A disposable battery, you likely need the 16340 rechargeable equivalent. If it uses a standard AA, look at the 14500 — but verify your device supports Li-ion voltage (3.6V vs 1.5V) before switching.

Typical capacity by size

Size	Typical mAh	Typical max CDR	Notes
14500	650–1200mAh	Up to 6A	Low capacity; mainly for compact devices
16340	550–950mAh	Up to 8A	Small cell; limited capacity by design
18350	700–1400mAh	Up to 10A	Good for compact high-drain builds
18500	1000–2000mAh	Up to 10A	Niche size; limited selection
18650	2000–4000mAh	Up to 56A+	Widest selection of any cylindrical size
20700	3000–4250mAh	Up to 35A	More capacity than 18650 same diameter
21700	3000–6500mAh	Up to 125A	Best combination of capacity and drain
26650	3500–7000mAh	Up to 41A	Large cell; ideal for high-capacity flashlights

Battery terms — quick reference

Key terminology you'll encounter when shopping for cells, chargers, and accessories.

mAh (milliamp-hours): Energy capacity of the cell. Doubling mAh roughly doubles runtime at the same current draw.

CDR / Max discharge: Continuous Discharge Rating in amps — the maximum safe continuous current without damage or risk.

Nominal voltage: Average operating voltage. Li-ion ≈ 3.6–3.7V. Full charge: 4.2V. Over-discharge cutoff: ~2.5V. LiFePO4 nominal: 3.2V.

Protected cell: Built-in PCB prevents overcharge (>4.2V), over-discharge (<2.5V), and short circuits. Adds ~3mm to total length.

Unprotected cell: No internal protection circuit. Slightly shorter and lighter. Requires a quality charger that terminates properly.

Flat top: Positive terminal is flush with the cell body. Standard for most unprotected cells. Required by some devices with flat contacts.

Button top: Small raised nub on the positive terminal. Some devices require this to make contact with their spring mechanism.

IMR: Lithium Manganese Rechargeable — more thermally stable at high discharge rates than older chemistries.

INR: Lithium Nickel Manganese Cobalt Oxide. Higher energy density than IMR. Very common in 18650 and 21700 cells.

NCR: Panasonic/Sanyo's designation for their high-capacity NCM cells, such as the NCR18650B.

LiFePO4 (LFP): Lithium Iron Phosphate. Safer, 2,000–5,000+ cycle life, lower energy density, 3.2V nominal.

BMS: Battery Management System — protects multi-cell packs from overcharge, over-discharge, cell imbalance, and short circuits.

Series / Parallel (S/P): "S" adds voltage; "P" adds capacity. A 4S2P pack has 4 groups of 2 parallel cells in series.

PVC wrap: The colored heat-shrink sleeve on a battery. A torn or damaged wrap is a safety hazard — replace it immediately.

Fish paper: Electrical insulation placed at terminal ends in DIY packs to prevent accidental short circuits.

Grade A cell: First-production, factory-fresh cells tested to full rated capacity and specifications.

Cycle life: Charge-discharge cycles before capacity drops to 80% of original. Li-ion: ~300–500; LFP: 2,000+.

Self-discharge: Rate of charge loss when idle. Li-ion: ~2–3%/month. NiMH loses significantly more.

C-rating: Multiplier of capacity for charge/discharge rate. 1C on 3000mAh = 3A. 10C = 30A.

Tabless design: Electrode tabs replaced by full-width contact rings. Reduces internal resistance, improves heat dissipation under high loads.

💡 When in doubt, check your device's manual — it will specify the cell size and minimum CDR required. Never exceed your device's rated discharge current.