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Asus M5 Replacement Battery 11.1V 2200mAh A31-S5

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From $51.99 USD $63.99
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Fits Asus M5, S5, M5000, S5000 notebooks; replaces A31-S5, A32-S5, 70-N8V1B1100, 70-N8V1B2100, 70-N8V1B3100, 90-N8V1B3000, 90-N8V1B3100, 90-N8V1B4100, S5NBTB1A, S5NBTW1B, 70-NHA2B1000, 70-NHA2B2000, 90-NHA2B1000, 90-NHA2B2000, A31-W5F, A32-W5F.
11.1V nominal, 2200mAh capacity—24.42Wh total energy; restores full charge cycles on machines that dropped to partial capacity.
Connector slides into the battery bay with a locking tab on the left side; orientation locks one way only, no forcing required.
We bench-tested this cell in an M5 under sustained CPU and display load; BMS held steady voltage through the test run with no early cutoff.
After installation, run a complete discharge down to hibernation-cutoff, then charge uninterrupted to 100%—this resets the BIOS battery learn cycle and clears false health warnings.
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

11.1V

Amp

2200mAh

Asus M5 / S5 Series — 11.1V Li-ion Replacement Battery (A31-S5 / A32-S5)

This is an 11.1V 2200mAh Li-ion replacement battery for the Asus M5, S5, M5000, and S5000 notebook series. It cross-references OEM part numbers A31-S5, A32-S5, A31-W5F, A32-W5F, and a range of 70-N and 90-N Asus codes. Capacity is 24.42Wh — matching the original cell specification.

  • M5 / S5 series compatibility: These models share a common 11.1V three-cell architecture and the same physical connector pinout. The BMS handshake uses the same SMBus protocol across the M5, S5, M5000, and S5000, so one cell works across all variants without firmware differences.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on an M5-series unit. The BMS accepted the new cell cleanly, balancing all three cell groups without triggering an over-voltage fault. Charge current tracked normally from 0% to cutoff.
  • Post-install calibration on the Asus M5: After fitting this battery, run a single full discharge down to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears on first boot after any cell swap.

BIOS reporting poor battery health immediately after fitting a new cell

The Asus M5 BIOS reads health data stored in the battery's EEPROM. When a new cell arrives, that EEPROM data does not match the charge history the BIOS expects, so it flags the battery as degraded or unknown. This is a calibration state, not a fault with the cell. Running one full discharge-to-hibernate then a complete uninterrupted charge gives the BIOS enough data to rewrite its estimate. After one or two cycles, the health reading normalises.

Laptop shutting down at 20–30% remaining after battery swap

This happens because the fuel gauge IC is still using a voltage-to-capacity curve calibrated to the old, degraded cell. The new cell has a steeper voltage cliff under combined CPU and display load, so the BIOS triggers a hard shutdown before the gauge reaches zero. It is not a defective cell. Discharge fully to hibernate-cutoff twice in a row — this forces the fuel gauge IC to recalibrate its curve against the actual chemistry of the new cell. After recalibration, the cutoff point drops back to the correct level near 3.0V per cell.

Compatible Models

M5 S5 M5000 S5000 W5000A M5000NP M5200N M52N M5600N M5N S5200Ns S5200Ne S52N S5N S5Ne W5600A W5A M5A M500A M500N M5000A M5000N S5A S5000A S5000N S5200 S5200N

Replaces Part Numbers

A31-S5 A32-S5 70-N8V1B1100 70-N8V1B2100 70-N8V1B3100 90-N8V1B3000 90-N8V1B3100 90-N8V1B4100 S5NBTB1A S5NBTW1B 70-NHA2B1000 70-NHA2B2000 90-NHA2B1000 90-NHA2B2000 A31-W5F A32-W5F

Technical Specifications

Voltage11.1V
Amp Hours2200mAh
Capacity2200mAh
Rate24.42Wh
Gross Weight150g /5.29 oz
Approximate Weight150g /5.29 oz
Dimension 203.80 x 44.50 x 21.50mm

Product Highlights

  • Brand: Asus
  • Manufacturer: CS
  • Series: Standard
  • Color: Silver
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The Asus M5 shows 0% or "unknown battery" in Windows right after I put in the new cell — is it dead?

It is not dead. The Windows fuel gauge IC is reading EEPROM data from the old cell and has not yet mapped the new cell's voltage curve. Plug in the charger and let it charge uninterrupted to 100%, then discharge fully to hibernate-cutoff. After one complete cycle, Windows re-reads the updated EEPROM data and the percentage display corrects itself.

System info shows the wrong Wh rating for this battery — it says something different from 24.42Wh. Why?

The Wh figure shown in Windows or HWInfo pulls from the EEPROM "design capacity" field, which may carry a value written by the original manufacturer for a different cell configuration. The actual chemistry in this cell is rated at 24.42Wh at 11.1V and 2200mAh. The discrepancy is a stored value conflict, not a capacity shortfall — run a full calibration cycle and the reported figure will update to match the real cell data.

My M5 charging stops at around 80% and will not go higher — is the new battery at fault?

This is almost always a BIOS-level charge limit, not a fault with the replacement cell. Asus laptops with certain BIOS versions include a battery health charging mode that caps charge at 80% to reduce cell stress. Check BIOS settings under Power Management or MyASUS software for "Battery Health Charging" and set it to Full Capacity Mode. Once disabled, the cell will charge to the full 11.1V cutoff.

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