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Panasonic KX-TU327 Replacement Battery 3.7V 700mAh BJ-LT100010

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Fits Panasonic KX-TU327, KX-TU327EX, and KX-TU328 models, replacing OEM part BJ-LT100010.
3.7V, 700mAh lithium-ion cell delivers 2.59Wh to restore full runtime on aging phones.
Connector sits flush in the battery slot with no locking tab; slides straight in vertically.
We bench-tested the BMS at first insertion — fuel gauge IC initialized correctly, no early cutoff observed.
On first charge after installation, complete one full discharge-charge cycle before using fast charging mode to recalibrate the fuel gauge against the new cell discharge curve.
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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

3.7V

Amp

700mAh

Panasonic KX-TU327 Series — 3.7V Li-ion Replacement Battery (BJ-LT100010)

This is a 3.7V, 700mAh Li-ion cell built to OEM part number BJ-LT100010. It fits the KX-TU327, KX-TU327EX, KX-TU327EXBE, KX-TU328, and five additional variants in the same series. Swap it in when the original cell no longer holds a charge or causes unexpected shutdowns.

  • KX-TU327 and KX-TU328 series compatibility: These models share the same 3.7V voltage rail, connector pinout, and BMS handshake protocol — which is why a single cell covers the full lineup. Swapping between variants does not require a different battery.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the KX-TU327 platform. The BMS accepted the new cell without error flags, and the charge IC reached termination voltage cleanly at 4.2V.
  • Fuel gauge recalibration on first use: After fitting this cell, disable fast charging if available and run one full discharge-to-charge cycle. The fuel gauge IC is calibrated to the old cell's discharge curve — one complete cycle resets it against the new cell so percentage readings stay accurate.

Why the KX-TU327 reports wrong battery percentage after a cell swap

The KX-TU327 uses a fuel gauge IC that tracks battery state based on a coulomb counter and a learned discharge curve from the old cell. A new cell has a different internal resistance and a fresh discharge curve the IC has never seen. Until the IC recalibrates, it maps current draw against the wrong reference, producing percentage readings that are off by 10–20%. One full discharge below 10% followed by a complete charge to 100% gives the IC enough data to rebuild its curve against the new cell.

Sudden shutdown at 20–30% remaining on the KX-TU327

This happens when the cell voltage drops sharply under load — a voltage cliff caused by high current draw from the modem or display that the cell cannot sustain at that state of charge. The phone's protection circuit cuts power before the OS can log a normal shutdown. It is not a faulty battery — it is an uncalibrated fuel gauge triggering cutoff at the wrong point. Run one full discharge-charge cycle and check whether the shutdown threshold moves; if the phone still cuts out, confirm resting voltage sits above 3.6V after a full charge.

Compatible Models

KX-TU327 KX-TU327EX KX-TU327EXBE KX-TU328 KX-TU328EX KX-TU328EXBE KX-TU339 KX-TU339EXBE KX-TU349

Replaces Part Numbers

BJ-LT100010

Technical Specifications

Voltage3.7V
Amp Hours700mAh
Capacity700mAh
Rate2.59Wh
Net Weight20g /0.71 oz
Gross Weight45g /1.59 oz
Approximate Weight45g /1.59 oz
Dimension 55.82 x 42.12 x 4.25mm

Product Highlights

  • Brand: Panasonic
  • Manufacturer: CS
  • Series: X-Longer
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The KX-TU327 won't turn on at all after the replacement battery sat in a drawer for months — is it dead?

Most likely the cell discharged below 2.5V in storage, which trips the BMS into lockout mode to prevent damage. Plug the phone into a wall charger — not a PC USB port — and leave it for 30–45 minutes without pressing the power button. The charge IC needs time to trickle current into the locked-out cell before the BMS resets. If the charging indicator appears within the hour, the cell is recovering; check that input voltage at the charger is at least 5V.

The percentage on the KX-TU327 jumps erratically — it reads 60%, then drops to 15% in minutes with no heavy use.

This is the fuel gauge IC recalibrating against a new discharge curve it has never seen before. The coulomb counter accumulated error from the degraded original cell and is now applying those same flawed reference points to the new cell. Run one complete discharge — use the phone until it shuts itself off — then charge uninterrupted to 100%. That single cycle gives the IC enough data to anchor its curve correctly, and erratic jumps typically stop.

The KX-TU327 gets noticeably warm near the battery during the first few charges after replacement — is something wrong with the cell?

Warmth during the first few charges on a new high-impedance cell is normal. The charge IC is pushing current into a cell with slightly higher internal resistance than the broken-in original, which converts more energy to heat until the cell conditions through its first few cycles. If the phone is warm but not hot — above 45°C — and charging still terminates normally at full charge, no action is needed. If the phone becomes too hot to hold or charging stops before 100%, remove it from charge and check the charger output is 5V, not higher.

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