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Black rectangular lithium-ion laptop battery with connector on one side

Beisite

Beisite C21N1701 39Wh 7.7V laptop battery for VivoBook S14 S406UA

SKU CH-FM7S-QX7NK

A 39 Wh, 7.7 V lithium-ion replacement battery for VivoBook S14 S406UA, K406UA and X406UA series laptops

  • Battery typeLithium-Ion
  • Battery voltage rating7.7 V
  • Battery capacity39 Wh
  • Product colorBlack
  • Product typeBattery
  • Compatible withFor VivoBook S14 S406U S406UA K406UA X406UA Series
  • 39Wh capacity powers extended work sessions
  • 7V lithium-ion chemistry matches original specifications
  • Replaces C21N1701, C21PQC5 and 0B200-02640000 part numbers
  • Fits VivoBook S14 S406UA, K406UA and X406UA series
  • Brand-new condition with 12-month warranty coverage

Replacement battery for VivoBook S14 S406UA

This 39Wh lithium-ion unit operates at 7.7V and replaces part numbers C21N1701, C21PQC5, 0B200-02640000 and 21CP3/82/138. It fits the VivoBook S14 S406U, S406UA, K406UA and X406UA series including many sub-models listed by the supplier. Buyers who need a higher capacity or a different voltage will not be served by this part.

When to replace the original pack

Swap the factory battery when it no longer holds a useful charge or when the laptop shuts down unexpectedly under load. The jump is worth it if the original cell has degraded after several years of daily cycling and you want the same 39Wh rating without modification. This battery does not increase runtime beyond the original specification.

Installation notes and common issues

Removal usually requires a small Phillips screwdriver and gentle prying of the bottom case; disconnect the old pack before fitting the new one. The most frequent problem is a loose connector that prevents the laptop from recognising the replacement, so seat the cable firmly and verify the battery indicator lights after the first boot.

How it compares

Measured against everything we stock in Laptop Chargers & Batteries, at today’s prices. Recalculated every night.

Price $44.99
Pricier than about 77% of the 27,790 comparable items (median $30.99).

Specifications

Product
Brand nameC21N1701
Model nameC21N1701
Part number21CP3/82/138
Product colorBlack
Product typeBattery
Power
Battery typeLithium-Ion
Battery voltage rating7.7 V
Battery capacity39 Wh
Compatibility
Compatible withFor VivoBook S14 S406U S406UA K406UA X406UA Series

Questions about this item

What laptop models does the C21N1701 39Wh 7.7V battery fit?

It replaces part numbers C21N1701, C21PQC5, 0B200-02640000 and 21CP3/82/138 in VivoBook S14 S406U, S406UA, K406UA and X406UA series, including models such as S406UA-BV021T, S406UA-BM231T and X406UA-1B.

How is the battery installed and what step is often missed?

Power off the laptop, disconnect the AC adapter, remove the bottom case screws, detach the old battery connector from the motherboard, fit the new 7.7V pack, reconnect the cable firmly, then reassemble; the step often missed is fully seating the connector before closing the case.

When will the 39Wh lithium-ion pack need replacement?

The 12-month warranty covers defects; typical lithium-ion life spans several hundred charge cycles, so replace the battery when run time drops noticeably below the original 39Wh capacity.

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