Microsoft Surface Pro 7.4V Replacement Battery 5670mAh
Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.
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Microsoft Surface Pro 7.4V Replacement Battery 5670mAh - 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.
Microsoft Surface Pro 7.4V Replacement Battery 5670mAh - is backordered and will ship as soon as it is back in stock.
Voltage
7.4V
Amp
5670mAh
Microsoft Surface Pro — 7.4V Li-Polymer Replacement Battery (P21GU9)
This is a 7.4V, 5670mAh Li-Polymer battery for the Microsoft Surface Pro and Surface Pro 64GB, including the Surface Pro 2. It matches the original cell dimensions at 244.80 × 96.20 × 5.16mm and connects to the same charging circuit. When the original cell degrades and the device loses portability, this unit restores it.
- Surface Pro and Surface Pro 2 fitment: Both generations use the same 7.4V two-cell Li-Polymer pack with the same BMS connector and voltage rail. The P21GU9 part number covers both. No adapter or modification needed.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Surface Pro unit. The BMS handshake completed on first connection, charge IC accepted current without fault codes, and the pack held voltage within spec through a full cycle.
- Fuel gauge recalibration after swap: After fitting this battery, run the Surface Pro down to automatic shutoff, then charge uninterrupted to 100% before unplugging. This single full cycle recalibrates the fuel gauge IC against the new cell and corrects the inaccurate percentage readings that appear after most battery replacements.
Surface Pro shutting down at 15–25% remaining
This is a voltage cliff issue, not a defective cell. When the display backlight and Wi-Fi radio draw current simultaneously, the combined load pulls cell voltage below the BMS cutoff threshold before the fuel gauge reaches zero. The gauge was calibrated against the old cell's discharge curve, so it reports 20% while the new cell's actual voltage is already at cutoff. One full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% resets the curve and stops the early shutdown.
Surface Pro percentage dropping faster than expected from 100%
Fast percentage drop from a full charge is fuel gauge drift — the IC is still using the old cell's capacity map. The new 5670mAh cell has a different discharge curve, and until the IC recalibrates, it misreads early voltage drop as large capacity loss. This is not a capacity defect. Discharge the device fully to automatic shutoff, then charge to 100% in one uninterrupted session. After that cycle, the percentage display should track accurately.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Microsoft
- 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
My Surface Pro shows 100% but drops to 60% within the first hour of use — is the new battery faulty?
It is not faulty. The fuel gauge IC on the Surface Pro is still calibrated to the old cell's discharge curve, so it misreads the new cell's voltage profile and reports large drops early. Run the device down to automatic shutoff without plugging it in, then charge uninterrupted to 100%. After that one full cycle, the IC recalibrates against the new cell and the percentage display stabilises.
Fast charging stopped working after I swapped the battery on my Surface Pro — what happened?
The Surface Pro's charge IC needs one completed charge cycle on the new cell before it negotiates the higher current rate. After a battery swap, it defaults to a conservative charge rate until the USB-PD handshake has been accepted once. Plug into the original Microsoft charger, let it run to 100% without interrupting the session, and fast charge should resume on the next charge cycle. Using a third-party charger for the first cycle can prevent the negotiation from completing correctly.
My Surface Pro gets noticeably warm near the bottom edge while charging the new battery — should I be concerned?
Warmth near the bottom edge during charging is normal with a fresh cell. The charge IC applies a higher current rate to a new pack at low state of charge, which generates more heat than a partially degraded cell would. Surface temperature should stay well below 40°C. If the device feels hot to the touch or the charge IC triggers a thermal fault and stops charging, check that the ventilation area around the kickstand hinge is not obstructed, then retry charging on a hard flat surface.
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