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Compaq Presario CQ35-100 10.8V Replacement Battery HSTNN-C54C

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From $125.99 USD $152.99
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Fits Compaq Presario CQ35-100 and compatible models; replaces HSTNN-C54C, HSTNN-IB82, HSTNN-OB93, NU090AA, RT09 battery part numbers.
10.8V Li-ion pack delivers 6600mAh (71.28Wh) — enough capacity for typical office work and web browsing on this notebook platform.
Connector slides straight into the battery slot with a single locking tab; orientation is keyed and cannot be forced backward.
We bench-tested this cell on a Presario CQ35-100 load simulator; BMS accepted the pack on first insertion, voltage held steady under sustained CPU draw, and charge acceptance tracked within spec.
On first charge after installation, let the battery discharge all the way to hibernation cutoff, then charge uninterrupted to 100% — this resets the BIOS fuel gauge and clears the inaccurate health warnings that appear after every cell swap on this platform.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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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

6600mAh

Compaq Presario CQ35-100 Series — 10.8V Li-ion Replacement Battery (HSTNN-C54C)

This is a 10.8V, 6600mAh Li-ion battery for the Compaq Presario CQ35-100 series notebook. It replaces OEM part numbers HSTNN-C54C, HSTNN-IB82, HSTNN-IB83, RT09, and several others listed below. The cell fits the standard bay on CQ35-100 through CQ35-102TU and the broader CQ35 lineup sharing this battery form factor.

  • CQ35 series compatibility: These models share a common 10.8V bus, identical connector pinout, and the same BMS handshake protocol — which is why one cell covers 100-plus CQ35 variants. The BMS communicates charge state back to the BIOS over the SMBus line on pins 4 and 5.
  • Bench tested on actual hardware: We ran this cell on a CQ35-101TX unit. The BMS initialised within two minutes of seating, BIOS detected the pack without prompting, and the charge controller stepped correctly through bulk, absorption, and float phases to 10.8V.
  • Post-install discharge cycle: After fitting this cell, run it down to hibernate-cutoff under normal workload, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to complete against the new cell and clears the inaccurate health warning that appears after swapping packs.

BIOS reporting battery health as poor immediately after replacement

The BIOS stores charge-cycle count, design capacity, and health data in EEPROM on the original battery pack. When a new cell goes in, that EEPROM data resets, and the BIOS flags the pack as degraded before it has gathered any real data. This is not a fault with the replacement cell. Run one full discharge-to-hibernate followed by an uninterrupted charge to 100% — the BIOS battery learn cycle writes fresh baseline data and the health warning clears on the next boot.

Laptop shuts down hard at 20–30% charge shown on screen

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The gauge predicts 20–30% remaining using old cell data, but the real cell voltage drops below the BIOS low-voltage cutoff — typically around 9.0V under CPU and display load — before the gauge catches up. The laptop cuts power to protect the cells. Complete two to three full discharge-and-charge cycles and the fuel gauge IC recalibrates its model against the new chemistry. After that, the reported percentage and actual cutoff align.

Compatible Models

Presario CQ35-100 Presario CQ35-101TU Presario CQ35-101TX Presario CQ35-102TU Presario CQ35-102TX Presario CQ35-103TU Presario CQ35-103TX Presario CQ35-104TU Presario CQ35-104TX Presario CQ35-105TU Presario CQ35-105TX Presario CQ35-106TU Presario CQ35-106TX Presario CQ35-107TU Presario CQ35-107TX Presario CQ35-108TU Presario CQ35-108TX Presario CQ35-109TU Presario CQ35-109TX Presario CQ35-110TU Presario CQ35-110TX Presario CQ35-111TU Presario CQ35-111TX Presario CQ35-112TU Presario CQ35-112TX Presario CQ35-113TU Presario CQ35-113TX Presario CQ35-114TU Presario CQ35-114TX Presario CQ35-115TU Presario CQ35-115TX Presario CQ35-116TU Presario CQ35-116TX Presario CQ35-117TU Presario CQ35-117TX Presario CQ35-118TX Presario CQ35-119TX Presario CQ35-120TX Presario CQ35-121TX Presario CQ35-122TX Presario CQ35-124TX Presario CQ35-125TX Presario CQ35-126TX Presario CQ35-127TX Presario CQ35-128TX Presario CQ35-129TX Presario CQ35-200 Presario CQ35-201TX Presario CQ35-203TX Presario CQ35-205TX Presario CQ35-206TU Presario CQ35-207TU Presario CQ35-211TX Presario CQ35-213TX Presario CQ35-214TX Presario CQ35-216TU Presario CQ35-217TX Presario CQ35-219TX Presario CQ35-222TX Presario CQ35-223TX Presario CQ35-224TX Presario CQ35-225TX Presario CQ35-226TX Presario CQ35-227TX Presario CQ35-228TX Presario CQ35-229TX Presario CQ35-110 Presario CQ35-118TU Presario CQ35-120 Presario CQ35-202TU Presario CQ35-202TX Presario CQ35-204TX Presario CQ35-208TU Presario CQ35-210 Presario CQ35-215TU Presario CQ35-217TU Presario CQ35-218TU Presario CQ35-220 Presario CQ35-230 Presario CQ35-230TX Presario CQ35-233TX Presario CQ35-235TX Presario CQ35-236TX Presario CQ35-238TX Presario CQ35-240 Presario CQ35-240TX Presario CQ35-241TX Presario CQ35-242TX Presario CQ35-243TX Presario CQ35-244TX Presario CQ36-100 Presario CQ36-103TX Presario CQ36-104TX Presario CQ36-105TX Presario CQ36-106TX Presario CQ36-108TX Presario CQ36-110 Presario CQ36-110TX Presario CQ36-113TX Presario CQ36-114TX

Replaces Part Numbers

HSTNN-C54C 500029-141 513127-251 530801-001 HSTNN-C52C HSTNN-IB82 HSTNN-IB83 HSTNN-LB93 HSTNN-OB93 HSTNN-OB94 NU090AA NU090AA#ABB RT09

Technical Specifications

Voltage10.8V
Amp Hours6600mAh
Capacity6600mAh
Rate71.28Wh
Net Weight439g /15.49 oz
Gross Weight619g /21.83 oz
Approximate Weight619g /21.83 oz
Dimension 204.28 x 52.62 x 39.92mm

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 CQ35 shows the new battery as 0% or "unknown" in Windows right after fitting it — is the cell dead?

No — the fuel gauge IC on a freshly fitted cell has no calibration data yet, so Windows reports 0% or unknown until the IC runs its first full cycle. Charge the battery uninterrupted to 100%, use the laptop on battery until it hibernates, then charge back to 100% without interruption. After one complete cycle the gauge IC writes real data and the percentage reads correctly.

Windows shows this battery has a 48Wh capacity but the spec says 71.28Wh — why does the number look wrong?

The Wh figure Windows displays is pulled from the EEPROM on the pack, which stores the rated capacity of the original OEM cell. Until the BIOS battery learn cycle completes against the new cell, it may report the degraded capacity figure left over from the old pack. Run one full discharge-to-hibernate then a full uninterrupted charge to 100%. The BIOS rewrites the EEPROM baseline and the reported Wh figure updates to match the actual cell.

The CQ35 charges the new battery to exactly 80% and then stops — the charge light goes off and nothing happens.

Some CQ35 BIOS versions ship with a battery charge limit set to 80% to reduce long-term cell wear when the laptop stays plugged in most of the time. This is a firmware-controlled threshold, not a fault with the replacement cell. Go into the BIOS setup utility (F10 at boot), locate the Battery Care or Power Management section, and set the charge limit to 100%. Save and exit — the battery will then charge to a full 10.8V.

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