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
6600mAh
Compaq Presario CQ42-130TU Series — 10.8V Li-ion Replacement Battery (HSTNN-CB0W)
This is a 10.8V, 6600mAh (71.28Wh) lithium-ion battery for the Compaq Presario CQ42 series, including the CQ42-130TU, CQ42-136TU, CQ42-137TU, CQ42-138TU, and over 225 additional CQ42 variants. It cross-references OEM part numbers HSTNN-CB0W, HSTNN-CB0X, HSTNN-IB0X, HSTNN-LB0W, HSTNN-Q61C, HSTNN-Q62C, 586006-321, 593554-001, and WD548AA, among others. The connector and BMS pinout match the original HP/Compaq battery tray exactly.
- CQ42 series compatibility: All CQ42 variants in this lineup share the same 10.8V three-cell-series architecture, identical connector housing, and the same BMS communication protocol over the SMBus data pin. One battery part number covers the entire platform because the charge management IC handshake does not differ between sub-models.
- Bench tested on actual hardware: We ran this cell on a Presario CQ42 chassis and confirmed the BMS completed a full charge cycle without triggering a protection cutoff. Capacity readout via HWMonitor settled within the expected range of the rated 71.28Wh after two full cycles.
- First-cycle recalibration on the CQ42: After installing, run one full discharge to the hibernate-cutoff threshold, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell data and clears the inaccurate health warning that appears after every cell swap on CQ42 hardware.
BIOS reporting battery health as poor after a CQ42 cell swap
The CQ42 BIOS reads health status from EEPROM data written to the battery's fuel gauge IC — not from live voltage. When a new cell arrives, that EEPROM carries factory-default values the BIOS has never seen before, so it flags the battery as unknown or degraded. Running one complete discharge-to-hibernate followed by an uninterrupted full charge gives the fuel gauge IC enough data to write accurate cycle and capacity values. After that cycle completes, the health status in BIOS and Windows Battery Report corrects itself without any firmware intervention.
CQ42 shutting down at 20–30% state-of-charge shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The IC uses the old cell's discharge profile to estimate remaining charge, so it reports 25% while the real cell voltage has already dropped below the minimum load threshold under combined CPU and display draw. The laptop hits the hardware undervoltage cutoff and shuts down before the OS fuel gauge reaches zero. Run two full discharge-to-hibernate and recharge cycles — by the second cycle the IC recalculates the curve and the shutdown point should shift below 5% remaining.
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
My CQ42 shows the new battery as "unknown" or 0% in Windows immediately after fitting it — what's wrong?
The Windows fuel gauge IC is reading EEPROM data from the new cell that doesn't match any prior charge history, so it returns an unknown state instead of a percentage. This is not a fault with the battery or the laptop. Run one full discharge to the hibernate-cutoff point, then charge uninterrupted to 100%. After that single learn cycle the fuel gauge IC writes calibrated data and the percentage reads correctly.
The replacement battery shows 47Wh in System Information but the rated capacity is 71.28Wh — is the cell faulty?
No. The Wh figure in Windows System Information is pulled from the EEPROM's design-capacity register, which holds factory default values from the cell manufacturer — not the actual chemistry in this specific pack. After two full discharge and recharge cycles, the fuel gauge IC overwrites that register with measured data. If the Wh figure still reads low after two cycles, open Battery Report (powercfg /batteryreport) and check FULL CHARGE CAPACITY against DESIGN CAPACITY — those two values calibrating toward each other confirms the cell is performing correctly.
The CQ42 still cuts off at around 25% after two cycles — charge won't go past that point on battery power alone. What's causing it?
Check whether HP Battery Check or the BIOS has a charge limit active. Some CQ42 BIOS versions ship with a battery care mode that caps charge at 80% to reduce cell wear — this is a firmware setting, not a battery fault. Enter BIOS setup (F10 on boot), navigate to System Configuration, and confirm Battery Care Mode is set to Full Charge. Save and reboot, then run a full charge cycle to 100%.
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