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18650 Series Packs – Increase Voltage, Power High-Voltage Devices, Custom Configurations Available
Welcome to our 18650 Series Packs collection. When your device requires an operating voltage higher than a single 3.7V (or 3.2V LiFePO₄) cell, and you want to avoid bulky lead-acid batteries or expensive proprietary packs, series-connected 18650 battery packs offer the most flexible and cost-effective solution. By connecting cells positive-to-negative in a daisy-chain configuration, the pack voltage multiplies while capacity (mAh) remains unchanged. This collection offers standard 2S (7.4V), 3S (11.1V), 4S (14.8V), and higher series configurations—ideal for power tools, e-bikes, medical equipment, robotics, RC models, and any application requiring DC supply above 5V.
Core Advantages
- Additive Voltage – Power High-Voltage Devices: Total pack voltage = single cell nominal voltage × number of series cells. Examples: 2S = 7.4V (suitable for 6V–8.4V devices); 3S = 11.1V (9V–12.6V); 4S = 14.8V (12V–16.8V).
- Capacity Remains Constant: Total pack capacity equals that of a single cell (e.g., a 3S pack using 3500mAh cells remains 3500mAh). Ideal for applications requiring higher voltage without the need for massive capacity.
- Flexible Voltage Customization: Configure any number of series cells—from 2S to 10S+—to precisely match motor drive voltages, audio amplifier rails, and industrial controller inputs.
- Compatible with Standard Charging Solutions: Packs can be safely charged using a balance charger or an integrated BMS protection board for convenient charge management.
- Compact & High Power Density: Compared to equivalent-voltage lead-acid or NiMH packs, 18650 series packs are significantly lighter, smaller, and deliver a flatter discharge curve.
Series (S) vs. Parallel (P) – Key Distinction
| Feature | Series (S) | Parallel (P) |
|---|---|---|
| Voltage | Adds up (e.g., 3S = 11.1V) | Same as single cell (3.7V / 3.2V) |
| Capacity | Same as single cell | Adds up (e.g., 2P = 2× capacity) |
| Discharge Current | Limited by weakest cell in series | Adds up |
| Best Suited For | Devices requiring higher voltage | Longer runtime at same voltage |
Typical Series Pack Configurations
| Configuration | Nominal Voltage | Full Charge Voltage | Suitable Device Range | Typical Application |
|---|---|---|---|---|
| 2S (2 cells) | 7.4V | 8.4V | 6V – 8.4V | RC toys, portable speakers |
| 3S (3 cells) | 11.1V | 12.6V | 9V – 12.6V | Power tools, RC models, drones |
| 4S (4 cells) | 14.8V | 16.8V | 12V – 16.8V | E-scooters, medical devices, robotics |
| 5S (5 cells) | 18.5V | 21.0V | 15V – 21V | E-bikes, high-power audio amps |
| 6S (6 cells) | 22.2V | 25.2V | 18V – 25.2V | Garden tools, light EVs |
| 7S (7 cells) | 25.9V | 29.4V | 24V systems | Electric wheelchairs, AGVs |
Note: Voltages above based on 3.7V nominal Li-ion cells. For 3.2V LiFePO₄ series packs, please contact us separately.
Cell Matching & Safety – Critical for Series Packs
- Strict Capacity & IR Matching: All cells in a series string must be matched for capacity (±3%) and IR (±5mΩ). Mismatched cells lead to overcharge/over-discharge of individual cells, causing safety hazards and rapid capacity fade.
- Balance Charging or BMS is Mandatory: Voltage imbalance between series cells is inevitable over time. Always use a balance charger or a BMS with balancing function to periodically equalize cell voltages and maximize pack lifespan.
- Same Brand & Batch – No Exceptions: Series cells must be identical make, model, and production batch. Never mix old and new cells, or different cell chemistries.
- Proper Welding & Insulation: Use pure nickel or nickel-plated steel strips for low-resistance connections. Install insulating separators between cells to prevent vibration-induced shorts.
Typical Applications for 18650 Series Packs
| Application | Recommended Series | Why Series |
|---|---|---|
| Power Tools (Drills, Saws, Impact Drivers) | 3S–5S, high-drain cells | Provides high voltage and current for strong torque |
| RC Models / Drones | 3S–6S, high-drain cells | Matches brushless motor KV rating for burst power |
| E-Bikes / E-Scooters | 10S–13S (36V/48V systems) | Standard voltage platforms for pedal-assist systems |
| Portable Medical Devices (Suction Pumps, Monitors) | 3S–4S, with BMS | Stable high-voltage DC with built-in safety redundancy |
| Mobile Robots / AGVs | 6S–7S (24V systems) | Compatible with industry-standard 24V motor drivers |
| Portable Audio / Amplifiers | 2S–3S | Supplies >5V required by amplifier ICs |
| Emergency Lighting / Backup Power | 3S–4S | Direct replacement for 12V lead-acid, lighter weight |
Why Choose Our 18650 Series Packs?
- Precision Cell Matching: Every series pack is assembled using capacity-sorted (≤3% variance), IR-matched (≤5mΩ deviation), and voltage-balanced (±0.02V) Grade-A cells to ensure string consistency.
- Professional Spot Welding: Constructed with 0.15mm–0.2mm pure nickel-plated steel strips for low-resistance, high-current handling and durable weld joints.
- Flexible Customization: Beyond standard 2S–6S, we offer custom series counts (7S–20S+), silicone lead wires, connectors (XT30, XT60, XT90, EC3, DC barrel), and integrated balancing BMS.
- Optional BMS Integration: Add a common-port or separate-port BMS providing overcharge, over-discharge, overcurrent, short-circuit, and passive balancing protection—enabling true "plug-and-play" safety.
- Robust Insulation: Each pack is finished with premium PVC heat shrink and insulating separators, with clearly marked positive and negative terminals.
- Quality Assurance: 12‑month warranty and dedicated technical support.
⚠️ Usage & Safety Notes
- Use a Proper Charger: Series packs require a Li-ion balance charger matched to the series count, or a dedicated charger for BMS-equipped packs. Never attempt to charge a series pack with a single-cell 4.2V charger.
- Periodic Voltage Balancing: Without an integrated BMS, measure individual cell voltages every 10–20 cycles. If any cell deviates by more than 0.1V, perform a balance charge.
- Avoid Over-Discharge: Do not discharge any single cell below 2.8V–3.0V (depending on cell specifications). Over-discharge causes permanent capacity loss.
- Storage Recommendation: For long-term storage, maintain pack voltage at 3.7V–3.8V per cell and store in a cool, dry environment.
👇👇👇 Browse the standard series pack configurations below to select the appropriate series count (2S–6S) based on your device voltage requirements. For higher series counts, specific connectors, or integrated BMS solutions, please contact our engineering team for a customized quote.
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