BTY-S11 MSI Wind 90 Replacement Battery 11.1V 4400mAh
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BTY-S11 MSI Wind 90 Replacement Battery 11.1V 4400mAh - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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.
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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.
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Disclaimer
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
BTY-S11 MSI Wind 90 Replacement Battery 11.1V 4400mAh - is backordered and will ship as soon as it is back in stock.
Voltage
11.1V
Amp
4400mAh
MSI Wind U100 Series — 11.1V Li-ion Replacement Battery (BTY-S11)
This is a 11.1V, 4400mAh Li-ion replacement battery for the MSI Wind 90 and Wind U100 series netbooks. It slots into the underside battery bay and powers the unit during mobile use. Capacity is 48.84Wh — matched to the original cell specification.
- Wind 90 and U100 platform fit: Both the Wind 90 and Wind U100 variants share the same battery bay geometry, connector pinout, and BMS handshake protocol. The BTY-S11 part number covers the full spread of Wind U100 regional SKUs — including the 002LA and 035US editions — because MSI used the same battery controller board across the lineup.
- Bench tested on actual hardware: We cycled this cell on a Wind U100 unit and confirmed the BMS completed a full charge handshake without error codes. Voltage held stable at 11.1V nominal across load, and the charge controller accepted the cell without fault flags.
- Post-install recalibration on Wind netbooks: After fitting this cell, run one full discharge down to the automatic hibernate cutoff, then charge uninterrupted to 100%. The Wind U100 BIOS uses a battery learn cycle — skipping this step leaves the fuel gauge reading a corrupted baseline from the old cell, causing the health warning on the battery status page.
BIOS reporting poor battery health immediately after fitting a new cell
The Wind U100 BIOS stores battery health data in EEPROM tied to the old cell's charge history. When a new cell goes in, that stored data does not clear automatically — the BIOS reads the new cell against stale parameters and flags it as degraded. This is not a fault with the replacement battery. Running one complete discharge-to-hibernate followed by an uninterrupted full charge forces the BIOS to rewrite the learn cycle against the new cell's actual capacity. After that cycle, the health status clears and the fuel gauge reads accurately.
Netbook shutting down abruptly at 20–30% charge shown on screen
This happens when the cell voltage drops below the BMS cutoff threshold under simultaneous CPU and display load before the fuel gauge predicts it will. It is a calibration gap — not a defective cell. The fuel gauge IC has not yet mapped the new cell's actual voltage-to-capacity curve, so it allows the system to run into the voltage cliff. Run two full discharge-to-hibernate and full recharge cycles back-to-back. After the second cycle, the gauge IC recalibrates against real discharge data and the early shutdowns stop. Confirm the BIOS battery info shows a non-zero Wh value after calibration — target 48Wh or above.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: MSI
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The MSI Wind U100 BIOS is showing the battery as "unknown" or 0% right after I installed the new one — is something wrong with the cell?
Nothing is wrong with the cell. The Wind U100 stores fuel gauge data in EEPROM from the previous battery, and the new cell has no matching history yet, so the BIOS returns an unknown or zero reading on first boot. Run one full discharge down to hibernate cutoff, then charge uninterrupted to 100%. That single learn cycle writes fresh EEPROM data against the new cell and clears the unknown status.
The battery percentage on my Wind 90 jumps around wildly — it reads 60%, then a few minutes later shows 85%, then drops to 40%. What's causing that?
The fuel gauge IC on the Wind U100 and Wind 90 uses historical charge data to estimate state of charge. A brand-new cell has no history in the IC, so the readings oscillate until calibration catches up. We see this on the bench for the first two to three cycles with every new cell. Run two complete discharge-to-hibernate and full recharge cycles back-to-back without interruption. After the second cycle the gauge settles and tracks accurately within a few percent.
My Wind U100 system info shows the battery as 37Wh even though the spec says 48.84Wh — is the battery underpowered?
The Wh figure shown in system info is pulled from EEPROM data written during the battery learn cycle — it does not read the cell's chemistry directly. If the learn cycle hasn't completed yet, the BIOS reports the last rated value from the old degraded cell, which is usually well below actual capacity. Complete one full discharge to hibernate followed by a full uninterrupted charge. After that cycle, the BIOS recalculates and the Wh figure should update to reflect the actual 48Wh range of the new cell.
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