We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Black rectangular lithium-ion phone battery with gold connectors

KingSener

KingSener F21 Pro laptop battery 2170mAh 3.85V 8.3545WH

SKU CH-VMXP-B479E MPN F21

A 2170 mAh, 3.85 V lithium-ion replacement battery for the Duo Qin F21 Pro and F21 Pro+ phones

  • Battery Voltage3.85V
  • Battery Capacity2170mAh/8.3545WH
  • 2170 mAh capacity extends phone runtime
  • 85 V lithium-ion chemistry delivers stable power
  • 3545 Wh energy rating matches original specification
  • 100 % new cells ensure full charge performance
  • Direct replacement for Duo Qin F21 Pro and F21 Pro+

Replacement battery for Duo Qin phones

This KingSener F21 Pro battery replaces the original power source in Duo Qin F21 Pro and F21 Pro+ phones. It uses Li-ion chemistry rated at 2170mAh and 3.85V for 8.3545WH of energy. The pack is built to the same physical size as the factory unit so it fits without modification.

Suits owners needing a fresh OEM-spec cell.

The cell matches the voltage, capacity and connector layout required by the two listed Duo Qin models. Phones with a different battery model, voltage or form factor will not accept this pack. Buyers who cannot confirm their original battery part number should verify before purchasing.

Capacity and voltage: 2170mAh at 3.85V

The 2170mAh / 8.3545WH rating at 3.85V is the single figure that decides compatibility. If the original battery carries the same voltage and capacity, this replacement will restore the intended run time. A mismatch in either value means the part is not suitable.

Highlights

  • 2170 mAh capacity extends phone runtime
  • 85 V lithium-ion chemistry delivers stable power
  • 3545 Wh energy rating matches original specification
  • 100 % new cells ensure full charge performance
  • Direct replacement for Duo Qin F21 Pro and F21 Pro+

Specifications

BrandKingSener
ModelF21 Pro
Part NumberF21 Pro
Battery Voltage3.85V
Battery Capacity2170mAh/8.3545WH

Questions about this item

Does this F21 Pro battery match the original dimensions and connector placement for my Duo Qin phone?

Yes, the KingSener F21 Pro is built to the same size as the original battery with identical connector positioning, ensuring a direct fit without modification.

What is the correct initial charging routine for this 2170mAh Li-ion cell?

Fully charge and discharge the battery from low current two to three times to condition the cells and reach the rated 8.3545 Wh capacity.

How should I store the 3.85V battery if the phone will be unused for several weeks?

Charge it above 80 percent, remove it from the device, and keep it in a cool, dry place; repeat the charge at least once per month.

Also in this aisle

People compared these

Same shelf, same checkout — eight coins and a 30-minute rate lock.