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HP ProBook 420 Replacement Battery 10.8V 4400mAh 587706-751

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From $105.99 USD $127.99
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Fits HP ProBook 420, 425, 4320t, 620 notebooks; replaces OEM part 587706-751, 593572-001, BQ350AA, HSTNN-CB1A, HSTNN-IB1A, HSTNN-DB1A, and eight additional HP battery part numbers.
10.8V 4400mAh lithium-ion cell delivers 47.52Wh to the ProBook's CPU and display during unplugged operation without AC power input.
Connector slides into the battery compartment slot with a single locking tab; orientation is keyed — insertion works only one way with the contact pins aligned correctly.
We bench-tested this cell against a ProBook 420 motherboard; the BMS accepted the new pack on first insertion and charged to full capacity without fault codes or thermal throttling.
After installation, run a full discharge to hibernation cutoff, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.
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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

10.8V

Amp

4400mAh

HP ProBook 420 / 620 Series — 10.8V Li-ion Replacement Battery (587706-751)

This is a 10.8V, 4400mAh (47.52Wh) Li-ion battery for the HP ProBook 420, 425, 4320t, 620, and related models. It replaces OEM part numbers including 587706-751, HSTNN-IB1A, HSTNN-CB1A, and HSTNN-LB1A. If your original cell no longer holds a charge or your notebook loses power off AC, this is the direct swap.

  • ProBook 420 / 425 / 4320t / 620 compatibility: These models share the same battery bay geometry, connector pinout, and BMS communication protocol. One cell fits all of them — no adapter or firmware workaround needed.
  • Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on ProBook 420 hardware. The BMS authenticated correctly, reported accurate state-of-charge to the OS, and held voltage within spec across the discharge curve.
  • Post-install calibration tip: After fitting this cell, run the notebook on battery until it hibernates at low charge, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after almost every cell replacement on this platform.

BIOS reporting battery health as poor immediately after fitting a new cell

The HP ProBook BIOS reads health data from EEPROM fields written by the original factory cell. A replacement cell ships with different EEPROM baseline values, so the BIOS flags it as degraded even when the cell is new. This is a data mismatch, not a fault with the battery. Running one full discharge-to-hibernate followed by a full uninterrupted charge lets the system rewrite its fuel gauge baseline against the new cell's actual chemistry. After one or two cycles, the health warning clears.

Notebook shuts down abruptly while showing 20–25% remaining

This happens when the cell voltage drops below the BMS cutoff threshold under combined CPU and display load before the fuel gauge reaches zero. The fuel gauge IC is still reading the old cell's discharge curve, so the percentage shown is wrong. The cell hits a voltage cliff — typically around 9.9V under load — and the BMS trips before the OS-reported percentage catches up. Run two full calibration cycles and the fuel gauge IC will remap its curve to the new cell's actual discharge profile.

Compatible Models

420 425 4320t 620 625 ProBook 4320s ProBook 4321s ProBook 4325s ProBook 4326s ProBook 4420s ProBook 4421s ProBook 4425s ProBook 4520s ProBook 4525s

Replaces Part Numbers

587706-751 593572-001 BQ350AA HSTNN-CB1A HSTNN-IB1A HSTNN-DB1A HSTNN-LB1A HSTNN-Q78C HSTNN-Q78C-3 HSTNN-Q78C-4 HSTNN-Q81C 587706-121 HSTNN-W79C-5 HSTNN-CB1B

Technical Specifications

Voltage10.8V
Amp Hours4400mAh
Capacity4400mAh
Rate47.52Wh
Net Weight320g /11.29 oz
Gross Weight630g /22.22 oz
Approximate Weight630g /22.22 oz
Dimension 268.20 x 95.00 x 48.00mm

Product Highlights

  • Brand: HP
  • 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

My HP ProBook shows "Battery: 0% available (plugged in, charging)" and never moves off zero — what's happening?

This is an EEPROM mismatch between the new cell and the data the HP BIOS cached from the old one. The fuel gauge IC hasn't yet mapped its baseline to the new cell's chemistry, so it reports zero state-of-charge even while current is flowing in. Disconnect AC, let the laptop run until it forces hibernate, then plug in and charge straight to 100% without interruption. After that first full cycle, the gauge IC resets its zero-point and the percentage will read correctly.

The ProBook's battery meter is jumping around — reads 60%, then 45%, then 70% within minutes of unplugging. Is the cell faulty?

The fuel gauge IC on this platform is calibrated against the discharge curve of whichever cell it last fully cycled. A brand-new cell has a slightly different curve than the worn cell it replaced, so the IC's voltage-to-percentage mapping is temporarily off. It is not a faulty cell. Run two complete discharge-to-hibernate and full-charge cycles and the IC will relearn the curve against the new chemistry — readings stabilise after that.

System information shows this battery as 38Wh but the spec says 47.52Wh — is something wrong?

Nothing is wrong with the cell itself. The Wh figure shown in HP's system info pulls from an EEPROM field that may carry the rated value from the original depleted cell rather than the replacement's actual spec. This is a data field discrepancy, not a capacity fault. Complete one full discharge-to-hibernate cycle followed by a full charge and check again — on most ProBook 420 units the EEPROM value updates to reflect the new cell after the learn cycle completes.

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