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Thomson 28106FE1 Ultra Slim DECT Replacement Battery 3.7V 500mAh

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From $22.99 USD $28.99
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Fits Thomson 28106FE1, 28115, 28118, RU1873GE3-A cordless handsets; replaces OEM battery PL-043043.
3.7V lithium-ion at 500mAh delivers rated talk time on this DECT handset platform.
Connector slides vertically into the battery slot beneath the handset grip with no locking tab.
We bench-tested the BMS on a Thomson base unit; full charge accepted within one cycle.
After installing, place the handset in the base for a full 16-hour charge before first use — lithium cells in DECT phones need a slow charge cycle to stabilize the BMS voltage reference.
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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

500mAh

Thomson 28106FE1 Ultra Slim Dect / 28115 / 28118 — 3.7V Li-ion Replacement Battery (PL-043043)

This is a 3.7V, 500mAh (1.85Wh) Li-ion replacement battery for the Thomson 28106FE1 Ultra Slim Dect cordless handset and related models. It also fits the 28115, 28118, and RU1873GE3-A handsets. OEM part number PL-043043. Slim 43 × 28 × 4mm profile matches the original battery bay.

  • 28106FE1, 28115, 28118, RU1873GE3-A compatibility: These Thomson handsets share the same 3.7V cell architecture, identical PL-043043 connector pinout, and the same BMS voltage acceptance range — one battery fits all four models without modification.
  • Bench tested on actual hardware: We cycled this battery through charge and discharge on a DECT handset bench rig. The BMS accepted charge from the base station without error, reached full voltage cleanly, and held standby draw within spec across multiple cycles.
  • First charge after installation: Li-ion cells in slim DECT handsets can sit in storage well below their resting voltage. Place the handset in the base immediately after fitting and leave it on charge for a full 16 hours before first use — this allows the cell to reach rated capacity from a depleted state rather than a partial one.

Talk time shorter than the original battery after replacement

A Li-ion cell shipped from storage arrives partially discharged — often below 3.5V. The first few charge cycles from that depleted state do not reach the cell's full 500mAh rated capacity. Capacity normalises after 3 to 5 full charge and discharge cycles. If talk time is still noticeably short after five cycles, check the base charging contacts for oxidation and clean them with a dry cloth.

Handset not pairing with the base after battery swap

Some Thomson DECT handsets store pairing data in volatile memory that resets when the battery is fully removed. Swapping the battery cuts all power momentarily, and the handset comes back up unpaired. To re-register, hold the paging or find button on the base for five seconds, then navigate to the handset's registration menu and follow the base-pairing sequence. The handset will re-pair at full DECT range once registered.

Compatible Models

28106FE1 Ultra Slim Dect 28115 28118 RU1873GE3-A

Replaces Part Numbers

PL-043043

Technical Specifications

Voltage3.7V
Amp Hours500mAh
Capacity500mAh
Rate1.85Wh
Net Weight10g /0.35 oz
Gross Weight35g /1.23 oz
Approximate Weight35g /1.23 oz
Dimension 43.00 x 28.00 x 4.00mm

Product Highlights

  • Brand: Thomson
  • 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 Thomson 28106FE1 base station shows no charge light after I put the new battery in — what's wrong?

A Li-ion cell arriving from storage can sit at 3.3V or lower, which sits outside the acceptance window some Thomson bases use to confirm a valid battery is present. Seat the handset firmly in the base and leave it undisturbed for 30 minutes — the base charging circuit will trickle-charge the cell up to the threshold voltage before switching to normal charge mode and lighting the charge indicator. If the light still does not appear after 30 minutes, clean the gold charging contacts on both the handset and base with a dry cloth and reseat.

The handset loses range within a few metres of the base after the battery swap — is the new battery faulty?

This is a voltage-sag issue, not a faulty cell. When the DECT radio transmits, it draws a short burst of current that causes cell voltage to dip momentarily. A new Li-ion cell that has not yet been fully conditioned holds a slightly lower resting voltage, and that sag pushes transmit power below the level needed to sustain range at distance. Run three full charge and discharge cycles on the handset and range will stabilise as the cell reaches its rated 3.7V working voltage.

The handset is fully charged but the battery drains completely overnight even when it's sitting idle — what causes that?

This is a standby draw problem, not a capacity fault. If the handset is not fully seated in the base cradle, the charging contacts do not make proper connection and the handset runs entirely off the battery rather than drawing from the base. Check that the handset clicks firmly into the base and that both sets of charging contacts are clean and making metal-to-metal contact. If the handset is correctly seated and the battery still drains overnight, check the base power adapter is supplying voltage — measure at the adapter output and confirm it reads between 6V and 9V DC.

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