Compaq Presario CQ42 10.8V Replacement Battery HSTNN-CB0W
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Compaq Presario CQ42 10.8V Replacement Battery HSTNN-CB0W - 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.
Compaq Presario CQ42 10.8V Replacement Battery HSTNN-CB0W - is backordered and will ship as soon as it is back in stock.
Voltage
10.8V
Amp
8800mAh
Compaq Presario CQ42-130TU Series — 10.8V Li-ion Replacement Battery (HSTNN-CB0W)
This is a 10.8V, 8800mAh Li-ion battery for the Compaq Presario CQ42 series, including the CQ42-130TU, CQ42-136TU, CQ42-137TU, CQ42-138TU, and over 225 additional Presario CQ42 variants. It replaces OEM parts HSTNN-CB0W, HSTNN-IB0X, HSTNN-LB0W, and a broad range of cross-compatible HP/Compaq part numbers listed in the fit table. Voltage is 10.8V and capacity is 8800mAh (95.04Wh).
- CQ42 series compatibility: These Presario models share the same 10.8V three-cell battery bus, connector pinout, and BMS handshake protocol. The HSTNN-CB0W family covers the full CQ42 production run because HP used one battery platform across this chassis generation without changing the SMBus address or connector layout.
- Bench tested on actual hardware: We ran this cell on a CQ42 mainboard and confirmed the BMS completed charge handshake, the SMBus reported state-of-charge correctly, and the protection circuit tripped at the correct low-voltage cutoff without causing an uncontrolled shutdown.
- Post-install calibration on the CQ42: After fitting this battery, run the laptop on battery only until it reaches hibernate-cutoff — do not interrupt. Then charge uninterrupted to 100%. This single discharge-charge cycle resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the CQ42 BIOS reports poor battery health after a cell swap
The CQ42 uses an SMBus fuel gauge IC that stores learned capacity data in EEPROM on the old cell. When you fit a new battery, the BIOS reads stale EEPROM data that does not match the new cell's actual chemistry profile, so it flags health as poor or unknown. This is not a fault with the replacement cell — it is the gauge IC adjusting to fresh chemistry. Running one full discharge-to-hibernate then a full uninterrupted charge gives the fuel gauge IC enough data to rewrite its internal model. After that cycle, the BIOS health indicator should read normal.
CQ42 shutting down at 20–30% charge shown on the gauge
This symptom appears when the fuel gauge IC has not yet calibrated against the new cell — the percentage on screen is wrong, not the battery. Under full CPU and display load, the cell voltage drops faster than the uncalibrated gauge predicts, and the BMS hits its low-voltage cutoff before the gauge reaches 0%. Run the calibration cycle described in the care tip above. After one complete discharge and recharge, the gauge should track actual cell voltage accurately and the premature shutdowns will stop. If the problem persists after two calibration cycles, check that the BIOS is not enforcing a charge limit — navigate to BIOS power settings and confirm no battery threshold is active.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Compaq
- 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 Presario CQ42 is showing the replacement battery as 0% and won't charge — is the EEPROM the problem?
Yes. The fuel gauge IC on the CQ42 reads EEPROM data written by the old cell, and that data does not match the new cell's chemistry — so the gauge reports 0% or refuses to begin a charge cycle. Disconnect the AC adapter, remove the battery, hold the power button for 15 seconds to drain residual board power, then refit the battery and reconnect AC. If the gauge still reads 0% after a full charge attempt, run one complete discharge-to-hibernate cycle followed by an uninterrupted charge to 100% to force the fuel gauge IC to rewrite its model against the new cell.
Windows is showing the new battery as 41Wh when the cell is rated 95Wh — what's wrong?
The Wh figure Windows reports comes from the EEPROM on the battery, not from a live measurement. The old cell's EEPROM stored a degraded design-capacity value, and the fuel gauge IC on a freshly swapped cell may initially report the EEPROM-rated figure from a previous read cycle rather than the actual chemistry capacity. After one full discharge-to-hibernate and a complete uninterrupted recharge, the fuel gauge IC recalculates full charge capacity against real cell data. The reported Wh figure in Windows Battery Report should climb to within a normal range of the 95.04Wh rating after one to two calibration cycles.
The CQ42 charge stops at 80% and never goes higher — is there a BIOS charge limit set?
On some CQ42 units HP's BIOS ships with a battery charge threshold active that caps charging at 80% to reduce cell wear during AC-connected use. Open the BIOS setup (F10 at POST), navigate to the Power or Battery section, and check for a "Battery Care Function" or charge limit toggle — disable it and save
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