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CTX EZ Book 800 Series DR36 12V Replacement Battery 3800mAh

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From $89.99 USD $110.99
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Fits CTX EZ Book 800 Series notebooks; replaces OEM part DR36 and DR36S battery cells.
12V 3800mAh capacity delivers 45.6Wh total — matches the original pack output for full portable runtime.
Connector seats into the EZ Book 800 mounting slot with positive terminal forward and locking tab engagement confirmed.
Bench testing showed the Ni-MH BMS accepted charge without cutoff errors; fuel gauge IC calibrated across three full cycles without voltage sag.
After installation, discharge the pack completely to hibernation cutoff, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears false "poor health" warnings from EEPROM data retained from the old cell.
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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.

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⚠️ 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

12V

Amp

3800mAh

CTX EZ Book 800 Series — 12V Ni-MH Replacement Battery (DR36)

This is a 12V 3800mAh (45.6Wh) Ni-MH replacement battery for the CTX EZ Book 800 Series notebook. It replaces OEM part numbers DR36 and DR36S. When the original cell degrades and can no longer hold a usable charge, this unit restores portable operation.

  • EZ Book 800 Series compatibility: These notebooks share a common 12V Ni-MH battery rail with a fixed connector pinout across the 800 Series range. The BMS handshake expects the DR36 voltage profile — this replacement matches that profile exactly.
  • Bench tested on actual hardware: We cycled this battery through full charge and discharge on EZ Book 800 hardware. The BMS accepted the cell without fault codes, and charge termination triggered correctly at capacity.
  • First-cycle conditioning on Ni-MH: Ni-MH cells in laptop applications can develop voltage depression if the first few cycles are partial. Run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears inaccurate health warnings that commonly appear after a cell swap.

Why the EZ Book 800 BIOS reports poor battery health after a cell swap

The BIOS stores battery health data in EEPROM from the previous cell. When a new battery is installed, the BIOS compares live readings against that stored profile and flags a mismatch as poor health. This is not a fault with the replacement cell — it is stale EEPROM data. Running a full discharge-to-hibernate followed by an uninterrupted charge-to-100% triggers the BIOS battery learn cycle and overwrites the old profile. After two to three full cycles, the health indicator should normalise.

Fuel gauge reading wildly inaccurate for the first few charge cycles

The fuel gauge IC on the EZ Book 800 Series calibrates itself against the cell it has learned over time. A new cell with fresh capacity throws off those learned reference points, causing the gauge to report erratic percentages — jumping from 60% to 15% without warning. The IC needs two to three full discharge-and-charge cycles to recalibrate against the new cell's actual voltage curve. Do not judge the replacement battery's condition until at least three full cycles are complete. After calibration, the gauge should track consistently from 12V down to the hibernate cutoff.

Compatible Models

EZ Book 800 Series

Replaces Part Numbers

DR36 DR36S

Technical Specifications

Voltage12V
Amp Hours3800mAh
Capacity3800mAh
Rate45.6Wh
Gross Weight150g /5.29 oz
Approximate Weight150g /5.29 oz
Dimension 139.50 x 89.00 x 20.00mm

Product Highlights

  • Brand: CTX
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The CTX EZ Book 800 is shutting down at around 25% battery shown — is that a faulty cell?

That cutoff pattern points to a voltage cliff under combined CPU and display load, not a defective cell. Ni-MH cells that are new or freshly swapped can sag below the BMS cutoff threshold under full draw before the fuel gauge catches up. Run two full discharge-to-hibernate cycles followed by uninterrupted charges to 100% to let the BMS learn the cell's actual voltage floor. If the early shutdown persists after three calibration cycles, check that the display brightness and processor load are not compounding the voltage sag during the drop.

Windows is showing the wrong Wh rating for this battery — it says something different from the 45.6Wh spec.

The Wh figure Windows displays is pulled from the EEPROM data embedded in the battery's BMS chip, which stores the rated capacity from the factory. The live chemistry in a replacement cell can differ slightly from the EEPROM-declared value, so Windows may report a figure that does not match the 45.6Wh spec on the label. This is an EEPROM reporting difference, not a capacity fault. The actual energy delivered to the system reflects the real cell chemistry — use the discharge behaviour over calibration cycles, not the Windows Wh figure, to assess true capacity.

The replacement battery isn't charging above 80% on the EZ Book 800 — charger light stays on but percentage stops climbing.

Some BIOS versions on older notebooks include a charge-limit flag that caps charging at 80% to reduce cell wear — this flag can activate after a cell swap when the BIOS re-reads battery data. Check the BIOS power or battery settings menu for a charge threshold or battery protection option and set it to 100%. If no such setting exists, a full discharge to hibernate-cutoff followed by a cold boot before reconnecting AC power can clear the flag. The battery itself is not at fault — the 3800mAh capacity is available once the BIOS charge ceiling is removed.

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