Description

The 21700 format in safe, long-life LiFePO4 chemistry — 2000+ cycles for home energy storage, solar street lighting, UPS and telecom backup where service life defines total cost of ownership.

THOR Power builds the THOR-21700-LFP40 into custom series/parallel packs — matched cells, BMS protection, nickel busbars, housing and the connector of your choice. Bare cells and welded modules are also available. Tell us your target voltage, runtime and discharge current, and our engineers will size the pack for you.

  • Proven 3.2 V nominal cylindrical cells from tier-1 suppliers
  • Long cycle life — typically several hundred to 1,000+ cycles
  • Built-in protection: overcharge, over-discharge, short-circuit
  • Custom series/parallel configuration, connector & BMS
  • UN38.3 / MSDS ready; CE, KC, ROHS on request

Why Choose THOR Power

A vertically integrated lithium battery manufacturer (Dengzhou Xinju New Energy) with the scale and engineering depth to deliver custom LiPo cells reliably at volume.

3 factories, 800+ staff
Source-manufacturer scale — not a trading company.
200+ engineers
R&D led by a chief battery scientist for rapid custom design.
60,000 pouch cells / day
Mostly exported overseas, across the US, Europe, Japan & Korea, SE Asia, Latin America and Africa.
Full certification
UN38.3, MSDS, CE, KC, UL, CB, PSE, RoHS.
Global export
US, Europe, Japan & Korea, SE Asia, Latin America, Africa.
End-to-end quality control
From raw material to finished cell.

Factory Photos

Automation Equipment

THOR Power factory — Automation Equipment
THOR Power factory — Automation Equipment

Production Line

THOR Power factory — Production Line
THOR Power factory — Production Line

Testing Equipment

THOR Power factory — Testing Equipment

Warehouse & Certifications

THOR Power factory — Warehouse & Certifications
THOR Power factory — Warehouse & Certifications
ModelTHOR-21700-LFP40
Battery TypeCylindrical Li-ion (IFR, steel can)
Capacity4000 mAh
CertificationsUN38.3 / MSDS (IEC 62133-2, CE, KC on request)
MOQQuoted per pack configuration; samples available
CustomizationCells, welded modules or packs, BMS, connector, wire length, housing

3.2V 4000mAh 21700 LiFePO4 Cell (LFP) | THOR-21700-LFP40

3.2V LiFePO4 21700 cell with 2000+ cycles for energy storage systems.

Get an Engineering Quote

Custom sizes, capacities, connectors & PCM/BMS available. MOQ-friendly. Samples in days.

    Battery Specification — THOR-21700-LFP40

    Mechanical Characteristics

    ModelTHOR-21700-LFP40
    Cell TypeCylindrical Li-ion (IFR, steel can)
    Cell Format21700
    Dimensions (Ø × H)Ø21.4 × 70.2 mm (max, bare cell)
    Dimension ToleranceDiameter +0.4 mm; Height +0.2 mm
    WeightApprox. 69 g
    TerminalFlat top (button top on request)
    Cathode / AnodeLiFePO4 / Graphite
    Pack Configuration1S1P to nSnP (fully custom)
    Cell ConnectionNickel strip spot welding / laser welding
    BMSCustom per pack configuration
    NTC ThermistorOptional
    ConnectorXT60 / JST / Molex (custom available)
    Electrical Specifications
    Nominal Voltage3.2 V
    Rated Capacity4000 mAh
    Energy12.8 Wh
    Charge Voltage3.65 ± 0.05 V
    Standard Charge0.5C constant current, CV to 3.65 V, cut-off 0.02C
    Max. Charge Current1C
    Discharge Cut-off Voltage2.50 V
    Standard Discharge0.2C
    Max. Continuous Discharge2C (high-rate cells on request)
    Internal Impedance≤ 30 mΩ (AC 1 kHz, fresh cell)
    Cycle Life≥ 2000 cycles @ 0.5C, ≥ 80% capacity
    Charge Temperature0℃ ~ 45℃
    Discharge Temperature-20℃ ~ 60℃
    Storage Temperature-10℃ ~ 45℃ (1 month)
    Self-Discharge≤ 3% per month
    Pack-Level BMS (custom configuration)
    Overcharge Detection3.80 ± 0.05 V per cell
    Overcharge Release3.60 ± 0.05 V
    Over-discharge Detection2.50 ± 0.08 V per cell
    Over-discharge Release2.90 ± 0.10 V
    Overcurrent ProtectionConfigured to pack continuous rating
    Short-circuit ProtectionYes, auto-recovery
    Cell BalancingPassive (active balancing on request)
    Temperature ProtectionNTC monitored, cut-off configurable

    Values shown are THOR Power standard specifications for this cell class. Final parameters are confirmed in the engineering datasheet for your configuration.

    Typical Applications — 3.7V 4000mAh

    GPS TrackersReliable runtime for asset, vehicle, and personal location trackers.
    Wearables & SmartwatchesSlim, lightweight power for fitness bands and smartwatches.
    Medical DevicesStable, safe output for monitors, thermometers, and handheld diagnostics.
    IoT ModulesLong standby power for connected sensors and smart devices.
    Bluetooth & AudioCompact power for earbuds, speakers, and wireless audio gear.
    Portable ElectronicsCameras, handhelds, and consumer gadgets needing a slim cell.

    Recently viewed

    Build a Custom 21700 Battery Pack

    Any series (S) and parallel (P) combination is available. Series raises voltage, parallel raises capacity. Below are the configurations we quote most often — all built from the 3.2 V 4,000 mAh cell on this page.

    ConfigurationCellsNominal VoltageCapacityEnergyTypical Use
    2S1P26.4 V4,000 mAh25.6 WhHandheld tools, RC devices, portable speakers
    3S1P39.6 V4,000 mAh38.4 WhDrones, medical carts, industrial scanners
    4S1P412.8 V4,000 mAh51.2 WhPower tools, robotic vacuums
    3S2P69.6 V8,000 mAh76.8 WhExtended-runtime handhelds, portable lighting
    4S2P812.8 V8,000 mAh102.4 Wh High-drain tools, mobile workstations
    10S4P4032.0 V16,000 mAh512.0 Wh E-bikes, portable power stations, energy storage

    Nominal voltage = 3.2 V per cell in series. Charge voltage = 3.65 V per cell (a 4S pack charges to 14.6 V). Capacity scales with cells in parallel. marks packs above 100 Wh, which ship as fully regulated Class 9 dangerous goods.

    Need a configuration that is not listed?

    Send us your target voltage, runtime and continuous discharge current. We size the pack, select the BMS, and quote tooling and samples.

    Talk to a Battery Engineer