Lenovo IdeaPad S9 11.1V Replacement Battery L08C3B21
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Lenovo IdeaPad S9 11.1V Replacement Battery L08C3B21 - 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.
Delivery and Shipping
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
⚠️ 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.
Lenovo IdeaPad S9 11.1V Replacement Battery L08C3B21 - is backordered and will ship as soon as it is back in stock.
Voltage
11.1V
Amp
5200mAh
Lenovo IdeaPad S9 / S10 Series — 11.1V Li-ion Replacement Battery (L08C3B21)
This 11.1V, 5200mAh Li-ion battery replaces the original cell in the Lenovo IdeaPad S9, S9e, S10, and S10e netbooks. It cross-references OEM part numbers including L08C3B21, L08S3B21, ASM 42T4590, FRU 42T4589, and 45K127, among others. Rated at 57.72Wh, it matches the voltage and form factor of the factory-installed pack.
- IdeaPad S9 / S10 platform fit: The S9, S9e, S10, and S10e share the same battery bay geometry, connector pinout, and 11.1V BMS handshake. One cell specification covers the whole netbook series, which is why the OEM part number list is long — Lenovo sourced from multiple suppliers across production runs without changing the electrical spec.
- Bench tested on actual hardware: We cycled this pack on an IdeaPad S10e and confirmed the BMS communicated charge state correctly through the SMBus interface. Charge acceptance ran to the full rated capacity without the controller tripping a premature cutoff.
- First-cycle calibration on the IdeaPad S-series: After installing, run one 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 the first boot after any cell swap.
BIOS reporting battery health as poor immediately after replacement
The IdeaPad S-series BIOS reads health data stored in the battery pack's EEPROM. A new cell ships with factory EEPROM values that don't match the discharge history the BIOS expects to see, so it flags the pack as degraded even though the cell is fresh. This is a data mismatch, not a hardware fault. Running the full discharge-to-hibernate then uninterrupted charge cycle forces the BIOS to rewrite its learned capacity baseline against the new cell. After one complete cycle, the health warning clears.
IdeaPad S10 shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC hasn't yet calibrated against the new cell's actual voltage curve. The old calibration data predicts the voltage floor based on the worn cell — the new cell hits that predicted floor while still carrying usable charge, so the OS calls a shutdown early. The fix is completing two to three full discharge-charge cycles so the fuel gauge IC can map the new cell's real voltage-to-capacity relationship. After calibration, the gauge should track accurately and the cutoff should shift back to below 5% remaining.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Lenovo
- 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
Why does Lenovo Power Manager show the new battery as "0% available (plugged in, not charging)" right after install?
This is a BMS initialisation issue — the controller hasn't yet authenticated the new pack's EEPROM data and holds the charge circuit open as a safety default. Shut the laptop down completely, remove the AC adapter, reseat the battery, then reconnect AC before powering on. If the symptom persists past one full boot cycle, force a BIOS battery reset by holding the power button for 30 seconds with both battery and AC removed, then reconnect and charge to 100%.
The IdeaPad S9e shows a completely different Wh rating in system info than what's printed on the battery label — which one is correct?
The figure in system info is pulled from the EEPROM embedded in the battery pack, which reflects the OEM-programmed rated value from the original supplier's production run. The label on the physical cell shows the actual measured chemistry capacity — 57.72Wh for this pack. The two numbers can differ by a small margin because Lenovo sourced cells across multiple suppliers without updating the EEPROM value each time. The label figure is the accurate one for this replacement.
Charge stops at exactly 80% and won't go higher — is the new battery faulty?
The IdeaPad S-series includes a BIOS-level charge threshold setting in Lenovo Energy Management or Power Manager that caps charging at 80% to reduce cell wear during periods of continuous AC use. This is a firmware setting, not a battery fault. Open Lenovo Energy Management, navigate to Battery Maintenance, and set the charge threshold to 100% (or disable Conservation Mode). After saving the change, the battery will charge to full on the next cycle.
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