Lenovo ThinkBook 16 G4 Replacement Battery L21C4PD8 15.36V
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Lenovo ThinkBook 16 G4 Replacement Battery L21C4PD8 15.36V - 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 ThinkBook 16 G4 Replacement Battery L21C4PD8 15.36V - is backordered and will ship as soon as it is back in stock.
Voltage
15.36V
Amp
4450mAh
Lenovo ThinkBook 16 G4 IAP/ARA Series — 15.36V Li-Polymer Replacement Battery (L21C4PD8)
This is a 15.36V, 4450mAh (68.35Wh) Li-Polymer battery for the Lenovo ThinkBook 16 G4 IAP and ARA series laptops. It replaces OEM part numbers L21C4PD8, L21D4PD8, L21L4PD8, L21M4PD8, and SB11F09739. Confirmed fit across multiple regional SKUs including 21CY001UPB, 21CY002XAD, and 21D10020KR, among 136 additional variants.
- ThinkBook 16 G4 platform fit: The IAP and ARA variants share the same battery bay dimensions, 15.36V four-cell architecture, and BMS communication protocol. One cell covers the full G4 generation regardless of regional SKU suffix.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on ThinkBook 16 G4 hardware. The BMS handshake completed without error, charge current stepped down correctly at the high-SOC taper threshold, and no fault flags were triggered during load cycling across CPU and display draw.
- Post-swap learn cycle for ThinkBook BIOS: After installing this cell, run one full discharge to hibernate cutoff, then charge uninterrupted to 100% without use. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on ThinkBook hardware.
Laptop shutting down at 20–30% shown after battery swap
This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. The new cell hits a voltage cliff under combined CPU and display load before the reported percentage reaches zero. The BIOS interprets the sudden voltage drop as a critical low and forces shutdown. Run two full discharge-to-hibernate cycles followed by uninterrupted charges to 100% — the fuel gauge recalibrates against the new cell's actual curve and the early shutdown stops.
BIOS reporting wrong Wh rating in system information after install
The Wh value shown in Lenovo Vantage or the BIOS power screen is read from EEPROM data stored on the battery controller, not measured from the cells directly. A new cell ships with EEPROM values that may differ slightly from what the old pack reported, so the system info screen can show an unexpected Wh figure. This is a data field difference between packs — it does not affect charge behaviour or capacity. Confirm the cell is charging and discharging normally; the EEPROM-reported figure is not a fault indicator.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Lenovo
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-Polymer
- Battery Type: Li-Polymer
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
Lenovo Vantage shows the new battery health as "Poor" immediately after install — is the cell faulty?
No. The health rating in Vantage is calculated against EEPROM data from the previous pack and the BIOS battery learn cycle has not yet run on the new cell. Install the battery, discharge fully to hibernate cutoff, then charge uninterrupted to 100%. After that cycle completes, the learn cycle resets and Vantage recalculates health against the new cell's actual data.
The battery percentage jumps around wildly for the first few charges — drops from 60% to 15% instantly, then recovers.
The fuel gauge IC inside the ThinkBook recalibrates its discharge model against each new cell over the first few cycles. Until it has enough data points, SOC estimates are inaccurate and the displayed percentage can jump non-linearly. Run two complete discharge-to-hibernate cycles followed by full uninterrupted charges to 100%. The gauge stabilises once it has mapped the new cell's voltage curve.
Charging stops at 80% and won't go higher — the laptop just sits at 80% plugged in indefinitely.
This is a BIOS-controlled charge threshold, not a battery fault. Lenovo ships ThinkBook units with Conservation Mode enabled by default in Lenovo Vantage, which caps charging at 80% to reduce long-term cell stress during always-plugged use. Open Lenovo Vantage, go to Power → Battery Settings, and switch from Conservation Mode to Normal Mode — charging will then proceed to 100%.
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