21700 6S1P Battery Box Kit | Weld-Free + Built-in 40A BMS | DIY 25.2V Backup Power Supply

Build Your Own Portable Power Station — No Welding Required

Turn six 21700 lithium cells into a compact, ready-to-use 25.2V backup power supply. This weld-free 6S1P battery box comes with a built-in 40A protection board (BMS) with static equilibrium, so you get overcharge and over-discharge protection, simple drop-in assembly, and reliable power for backup use, camping, DIY projects, and off-grid setups.

Why you'll love it

• No welding, no soldering: spring-loaded cell slots let you drop in six matched 21700 cells — no spot welder needed.
• Built-in 6S 40A BMS: integrated protection board with static equilibrium guards against overcharge and over-discharge while keeping cells balanced.
• Real-world power: full-charge voltage of 25.2V with an operating range of DC 18–25.2V; recommended continuous discharge 20A (sustainable 10–20A, instantaneous up to 40A depending on the cells you install).
• Charge your way: recommended charging current 5A (regular 5–8A) using a 25.2V lithium battery charger.
• Three output interfaces, all in parallel: DC5.5-2.5 port (25.2V lithium charger connection / small-current discharge), XT30 (low-power charge or discharge), and XT60 (large-current charge or discharge), plus a power switch (left = closed, right = open) to cut output when you're finished.

Specifications (as listed by the supplier)

• Configuration: 6S1P (6 strings, 1 parallel)
• Full-charge voltage: 25.2V
• Operating voltage range: approx. DC 18–25.2V (does not support voltage regulation)
• Protection board: 6S 40A with static equilibrium
• Recommended charging current: 5A suggested; 5–8A regular
• Recommended continuous discharge: 20A; sustainable 10–20A; instantaneous 40A (depends on cells used)
• Interfaces: 1x DC5.5-2.5 socket, 1x XT30 male, 1x XT60 male, 1x power switch — all three interfaces in parallel, directly connected to the protection board
• Cell slots: spring-loaded (manganese steel, nickel); does not support pointed non-standard batteries
• Size (21700 model): 168 x 87 x 28 mm (L x W x H, excluding plastic columns)
• Type: battery storage box; Model Number: 18650/21700

Important — please read before ordering

• Batteries NOT included: you supply your own six brand-new batteries.
• Cells must be matched: all batteries must be consistent in capacity, voltage, and internal resistance.
• Charger not included: use your own 25.2V 5A lithium battery charger (DC2.5 connector).
• Not for vehicle starting: this box does not support starting vehicles.
• Safety: do not expose all interfaces (risk of short circuit); turn the power switch off when finished; confirm your charger is a 25.2V lithium-battery charger only — do not mischarge.
• Overall capacity, endurance, and lifespan of the finished pack are determined entirely by the batteries you install.