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Acer Nitro 5 AN517 15.4V Replacement Battery AP21A7T

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From $91.99 USD $113.99
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Fits Acer Nitro 5 AN517-55-50P0 and replaces OEM part numbers AP21A7T, AP21A8T, KT0040G014.
15.4V 5650mAh Li-ion delivers 87.01Wh capacity to sustain gaming loads without voltage sag mid-session.
Connector slides straight into the battery slot with a latching tab that locks horizontally when seated correctly.
We bench-tested this cell in the AN517-55-50P0 under sustained CPU and GPU load; the BMS held stable voltage and cycled charge detection without errors.
On first charge after installation, run a full discharge down to hibernation-cutoff, then charge uninterrupted to 100% to reset the BIOS battery learn cycle and clear inaccurate health warnings.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

15.4V

Amp

5650mAh

Acer Nitro 5 AN517-55 / Predator Helios 300 PH317-56 — 15.4V Li-ion Replacement Battery (AP21A7T)

This is a 15.4V 5650mAh (87.01Wh) Li-ion battery for the Acer Nitro 5 AN517-55 series and Predator Helios 300 PH317-56 series laptops. It replaces OEM part numbers AP21A7T, AP21A8T, and KT0040G014. Install it when the original cell no longer holds charge or swells under the chassis.

  • Nitro 5 and Helios 300 shared platform: These models share the same 15.4V four-cell architecture, connector pinout, and BMS handshake protocol — one cell fits both lines without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Nitro 5 AN517-55 chassis. The BMS communicated correctly with the EC, reported accurate state-of-charge data, and balanced across all four cells without triggering a fault code.
  • Post-install calibration on Nitro 5: After fitting, run the laptop down to hibernate cutoff under normal load — gaming or a CPU stress test works — then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.

Why the Nitro 5 shuts down at 20–30% remaining after a battery swap

The Nitro 5 EC uses a fuel gauge IC to estimate remaining capacity based on learned discharge curves from the previous cell. After swapping to a new cell, those curves are stale. Under full CPU plus display load the voltage drops faster than the old model predicts, and the EC triggers a shutdown before the cell is actually empty. Run two full discharge-to-hibernate cycles under load to let the gauge IC rebuild its curve against the new cell's actual chemistry.

BIOS reporting the new battery as unknown or 0% after installation

This happens because the BIOS reads EEPROM data written to the old cell — manufacturer ID, cycle count, and design capacity — and flags a mismatch when it finds a fresh cell. It is not a fault with the replacement. Boot into the BIOS, navigate to the battery information screen, and confirm the voltage reads between 15.0V and 15.4V. If it does, exit and let Windows run a full charge cycle — the health status corrects itself once the fuel gauge IC logs its first complete charge event on the new cell.

Compatible Models

Nitro 5 AN517-55-50P0 Predator Helios 300 PH317-56-70C3 Nitro 5 AN517-55-713K Nitro 5 AN517-55-75R8 Predator Helios 18 PH18-71-72AS Predator Helios 18 PH18-71-92RQ Predator Helios 300 PH315-55-79AU Predator Helios 300 PH315-55-79FW Nitro 5 AN517-55-78NJ Predator Helios 300 PH315-54-760S Predator Helios 300 PH315-55-784Y Predator Helios 18 PH18-71-74M5 Predator Helios 18 PH18-71-71TC Predator Helios 300 PH315-55-751D Predator Helios 300 PH315-55-51BA Predator Helios 300 PH317-56-722C Nitro 5 AN517-55-73NJ Predator Helios 300 PH317-56-718D Nitro 5 AN517-55-72R4 Nitro 5 AN517-55-5794 Predator Helios 18 PH18-71-92HQ Predator Helios 18 PH18-71-764U Predator Helios 300 PH315-55-724G Predator Helios 300 PH315-55-70ZV Predator Helios 300 PH317-56-987C Nitro 5 AN517-55-73VP Nitro 5 AN517-55-74L0 Predator Helios 300 PH317-56-7929 Predator Helios 18 PH18-71-91U5 Predator Helios 18 PH18-71-79CV Predator Helios 300 PH315-55-764C Predator Helios 300 PH315-55-71WE Nitro 5 AN517-55-76QM Predator Helios 300 PH317-56-72SP Nitro 5 AN517-55-72GU Nitro 5 AN517-55-73WQ Predator Helios 18 PH18-71-94L2 Predator Helios 300 PH315-55-538Z Predator Helios 300 PH315-55-790G Predator Helios 300 PH315-55-795C Predator Helios 300 PH317-56-79UV Predator Helios 300 PH317-56-76E9 Nitro 5 AN517-55-77P1 Nitro 5 AN517-55-747X Predator Helios 18 PH18-71-998G Predator Helios 18 PH18-71-76FD Predator Helios 300 PH315-55-782K Predator Helios 300 PH315-55-72EA Nitro 5 AN517-55-77MX Predator Helios 300 PH317-56-78FW Nitro 5 AN517-55-72VY Predator Helios 18 PH18-71-72QZ Predator Helios 18 PH18-71-90JF Predator Helios 300 PH315-55-770K PREDATOR HELIOS 300 PH315-55-749G Predator Helios 300 PH317-56-75RR Predator Helios 300 PH315-55 Predator Helios 300 PH317-56-78YQ Nitro 5 AN517-55-79GW Nitro 5 AN517-55-70QP Predator Helios 18 PH18-71-98BE Predator Helios 18 PH18-71-917G Predator Helios 300 PH315-55-73N9 Predator Helios 300 PH315-55-78FC Nitro 5 AN517-55-77YT Predator Helios 300 PH317-56 Nitro 5 AN517-55-756P Predator Helios 18 PH18-71-93CJ Predator Helios 18 PH18-71-91CU Predator Helios 300 PH317-55-95XR Predator Helios 300 PH315-55-767B Predator Helios 300 PH317-56-77ZP Nitro 5 AN517-55-72FC Predator Helios 300 PH317-56-7292 Nitro 5 AN517-55-55AM Nitro 5 AN517-55-57WA Predator Helios 18 PH18-71-98Y4 Predator Helios 18 PH18-71-75P7 Predator Helios 300 PH315-55-75K6 Predator Helios 300 PH315-55-78LF Nitro 5 AN517-55-78KU Nitro 5 AN517-55-731L Predator Helios 300 PH315-55-791W Predator Helios 18 PH18-71-74ET Predator Helios 18 PH18-71-77YV Predator Helios 300 PH315-55-75GP Predator Helios 300 PH315-55-71SW Predator Helios 300 PH317-56-75UZ Nitro 5 AN517-55-738R Predator Helios 300 PH317-56-78LY Nitro 5 AN517-55-75H9 Nitro 5 AN517-55-53ZU Predator Helios 18 PH18-71-78F6 Predator Helios 300 PH315-55-70N1 Predator Helios 300 PH315-55-77UZ Predator Helios 300 PH315-55-78L7 Predator Helios 300 PH317-56-78SM Nitro 5 AN517-55-56G1 Nitro 5 AN517-55-523H Nitro 5 AN517-55-50NF Predator Helios 18 PH18-71-99ER Predator Helios 18 PH18-71-97FB Predator Helios 300 PH315-55-766X Predator Helios 300 PH315-55-79ZV Nitro 5 AN517-55-75R4 Predator Helios 300 PH317-56-710H Nitro 5 AN517-55-7501 Predator Helios 18 PH18-71 Predator Helios 18 PH18-71-784H Predator Helios 300 PH315-55-72J4 Predator Helios 300 PH315-55-796N Predator Helios 300 PH317-56-78LS Predator Helios 300 PH317-56-724M Predator Helios 300 PH317-56-773G Nitro 5 AN517-55-79QV Nitro 5 AN517-55-715X Predator Helios 18 PH18-71-90AU Predator Helios 18 PH18-71-97XX Predator Helios 300 PH315-55-750X Predator Helios 300 PH315-55-74FV Nitro 5 AN517-55-76Z7 Predator Helios 300 PH317-56-70XJ Nitro 5 AN517-55-74K4 Predator Helios 18 PH18-71-77CC Predator Helios 18 PH18-71-96A7 Predator Helios 300 PH315-55-58FY Predator Helios 300 PH315-55-76KG Predator Helios 300 PH317-56-74AG

Replaces Part Numbers

AP21A7T AP21A8T KT0040G014

Technical Specifications

Voltage15.4V
Amp Hours5650mAh
Capacity5650mAh
Rate87.01Wh
Net Weight368g /12.98 oz
Gross Weight628g /22.15 oz
Approximate Weight628g /22.15 oz
Dimension 287.00 x 74.30 x 9.80mm

Product Highlights

  • Brand: Acer
  • 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 Nitro 5 shows 87Wh in one system info tool but a different Wh reading in another — which is correct?

The 87.01Wh figure comes from the cell's rated chemistry spec stored in EEPROM. Third-party tools like HWiNFO read the EEPROM directly and show the rated value; Windows Battery Report calculates Wh from the fuel gauge IC's live voltage and current readings, so the two numbers rarely match until the gauge IC has completed a few full cycles on the new cell. Neither reading indicates a fault. Check back after two full charge-discharge cycles — the Windows figure will converge toward 87Wh as the gauge IC learns the new cell's actual capacity curve.

The laptop charges fine but the fuel gauge jumps erratically — showing 60%, then 80%, then 45% within minutes of unplugging.

The fuel gauge IC on the Nitro 5 EC calibrates its state-of-charge model against discharge data from the previous cell. With a fresh cell installed, the learned curve no longer matches real voltage behaviour and the gauge overshoots or undershoots. Run two full discharge cycles — down to hibernate cutoff under CPU and display load, then charge uninterrupted to 100% each time. After the second cycle the gauge IC rebuilds its curve against the new cell and the percentage readout stabilises.

Windows shows the new battery's health as "Consider replacing" or flags it in the battery report immediately after installation.

Windows generates that warning by comparing the current full-charge capacity reported by the fuel gauge IC against the EEPROM design capacity from the old cell's logged data. On a brand-new cell the gauge IC has not yet completed a learn cycle, so it under-reports full-charge capacity and trips the threshold. This clears on its own — charge to 100%, discharge to hibernate cutoff, then charge back to 100% without interruption. After that cycle Windows battery report should show full-charge capacity at or near 87Wh.

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