What Is an 18650 Battery: Specifications, Dimensions, Chemistry & OEM Selection Guide
An 18650 battery is a standardized cylindrical lithium-ion cell measuring 18.0mm in diameter and 65.0mm in length (±0.2mm). Operating at a nominal voltage of 3.6V–3.7V (with 4.20V charge termination limit and 2.50V–2.75V cutoff), it is manufactured in two primary performance tiers: High-Capacity Energy Cells (3,000mAh–3,500mAh, continuous discharge ≤ 8A–10A) for portable electronics, IoT beacons, and medical devices; and High-Drain Power Cells (2,000mAh–2,600mAh, continuous discharge up to 20A–30A) with internal impedance ≤ 13mΩ for power tools, robotics, and e-mobility traction.
1. 18650 Physical & Electrical Specification Matrix
Standard design parameters across leading industrial 18650 cells:
| Specification Parameter | High-Capacity Tier (Energy) | High-Drain Tier (Power) |
|---|---|---|
| Physical Dimensions | 18.3 × 65.1 mm (±0.2 mm) | 18.3 × 65.1 mm (±0.2 mm) |
| Nominal Working Voltage | 3.60V – 3.70V | 3.60V – 3.70V |
| Rated Capacity Envelope | 3,200mAh – 3,500mAh | 2,000mAh – 2,600mAh |
| Max Continuous Discharge Current | 3A – 10A (1C–3C) | 20A – 30A (10C–15C) |
| Internal AC Impedance (1kHz) | 25 – 40 mΩ | ≤ 13 mΩ |
| Average Cell Weight | 46.5g – 48.5g | 44.0g – 46.5g |
| Standard Cycle Endurance | ≥ 500 cycles (@ 0.5C / 80% DoD) | ≥ 800 cycles (@ 1C / 80% DoD) |
2. Flat Top vs. Button Top Configuration
OEM hardware integration must verify positive terminal compatibility:
- Flat Top Cells: Engineered for multi-cell pack assembly using automated spot-welding and nickel busbars. Lacks integrated PCM; overall length strictly 65.0mm.
- Button Top Cells: Features a raised terminal for spring-loaded single-cell battery compartments. Often incorporates an integrated Protection Circuit Module (PCM), increasing overall length to 67.0mm–69.0mm.
3. Custom 18650 Battery Pack Engineering by GEB
GEB engineers custom series-parallel (S/P) battery packs utilizing Tier-1 18650 cells. Every custom module includes precision laser welding, custom BMS protection (overcharge, overdischarge, short-circuit, multi-point NTC thermal sensing), and complete UN38.3/CE/UL certifications.
Featured Industrial Battery Packs & Solutions
Factory-direct Grade-A lithium battery models engineered for commercial and industrial OEM/ODM projects.
GEB 302025 3.7V 100mAh Lithium Polymer (LiPo) Battery Cell (3×20×25mm)
Grade-A GEB 302025 3.7V 100mAh LiPo battery cell (3×20×25mm, 2.4g). Ultra-thin 3mm flexible pouch cell with low IR and 500+ cycles for smart devices, audio wear, and IoT.
GEB 32650 3.2V 6000mAh Cylindrical LiFePO4 Battery Cell (32×65mm)
Grade-A GEB 32650 3.2V 6000mAh cylindrical LiFePO4 battery cell (32×65mm, 145g, 19.2Wh). Long cycle life (3000+ cycles) and high thermal safety for solar streetlights and ESS packs.
GEB 402025 3.7V 150mAh Lithium Polymer (LiPo) Battery Cell (4×20×25mm)
Grade-A GEB 402025 3.7V 150mAh LiPo battery cell (4×20×25mm, 3.5g). Ultra-compact flexible pouch cell with low IR and 500+ cycles for smart wearables, IoT, and medical sensors.
GEB 551525 3.7V 140mAh Lithium Polymer (LiPo) Battery Cell (5.5×15×25mm)
Grade-A GEB 551525 3.7V 140mAh LiPo battery cell (5.5×15×25mm, 3.4g). Compact lightweight lithium pouch cell with stable 1C discharge for wearables, fitness trackers, and IoT devices.
