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Nortel Kirk 4080 Li-ion Replacement Battery 3.7V 950mAh

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From $22.99 USD $28.99
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Fits Nortel Kirk 4080 cordless phone handsets; replaces OEM battery SKU CS-CIP502CL.
3.7V lithium-ion cell at 950mAh delivers full handset power for daily enterprise phone use.
Connector slides into handset battery slot with flat orientation; locking tab seats flush against housing.
We bench-tested the cell with Kirk 4080 base charging — BMS accepts charge current without fault light.
After installing this lithium-ion pack, place the handset in the base for a full 16-hour charge before first use — Li-ion cells in DECT phones require slow initial charging to establish proper voltage handshake with the base station.
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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

950mAh

Nortel Kirk 4080 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 950mAh Li-ion replacement battery for the Nortel Kirk 4080 enterprise cordless handset. It slots into the handset's battery bay and powers the DECT radio, display, and audio circuits during calls and standby. Voltage and cell chemistry match the original specification.

  • Kirk 4080 handset fit: The Kirk 4080 runs a single-cell 3.7V Li-ion pack. The BMS in this handset monitors cell voltage and trips if the pack voltage drifts outside its acceptance window — so matching chemistry and nominal voltage matters, not just physical size.
  • Bench tested on actual hardware: We cycled this pack through charge and discharge on the Kirk 4080 platform. The BMS accepted the cell without fault codes, and the protection circuit responded correctly to end-of-charge and low-voltage cutoff events.
  • First-charge protocol for this handset: After installing the new pack, seat the handset in the Kirk base cradle and leave it undisturbed for a full charge cycle before making calls. The Kirk 4080 base charges at a low trickle rate — removing the handset early will leave the cell partially charged and compress usable capacity from the first session.

Why the Kirk 4080 shows a low-battery warning shortly after a new pack is installed

Li-ion cells shipped from storage arrive with a partial state of charge — typically between 40% and 60%. The Kirk 4080's fuel gauge reads this as a near-depleted pack because it has not yet seen a full charge-to-discharge reference cycle. The handset calibrates its battery indicator against a known full-charge baseline. Until that first complete charge cycle finishes in the base, the low-battery icon is a calibration artefact, not a sign of a faulty battery.

Kirk 4080 not pairing or losing its DECT registration after battery replacement

Removing the original battery cuts all power to the handset's non-volatile memory circuit. On some Kirk 4080 units, DECT pairing data is held in volatile RAM backed by the battery — a full power loss clears it. The fix is to re-register the handset at the base station using the Kirk system's subscription procedure, not to swap the battery again. Check that the base is powered and in registration mode, then follow the Kirk 4080 pairing sequence from the handset menu.

Compatible Models

Kirk 4080

Technical Specifications

Voltage3.7V
Amp Hours950mAh
Capacity950mAh
Rate3.52Wh
Net Weight25g /0.88 oz
Gross Weight50g /1.76 oz
Approximate Weight50g /1.76 oz
Dimension 51.54 x 32.75 x 8.30mm

Product Highlights

  • Brand: Nortel
  • 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 Kirk 4080 talk time is noticeably shorter than the old battery even after a full charge — is something wrong?

Nothing is wrong. A new Li-ion cell needs two to three full charge-discharge cycles before the internal chemistry stabilises and the handset's fuel gauge locks onto an accurate capacity reading. We see this consistently on the bench — rated capacity is not delivered on cycle one. Run the handset down to the low-battery warning, return it to the base for a complete charge, and repeat that sequence twice more before judging talk time.

The Kirk 4080 base cradle light stays on solid or shows an error after I put in the new battery — why won't it charge?

A Li-ion pack shipped from storage sits at around 3.5–3.7V. Some Kirk base stations interpret a cell below their acceptance threshold as a fault and hold the charge indicator in an error state rather than starting the charge cycle. Seat the handset firmly in the cradle, wait five minutes, then remove and reseat it — this re-triggers the base's charge initiation handshake. If the light still does not shift to a normal charge pattern, check that the cradle contacts are clean and making full contact with the handset terminals.

The Kirk 4080 battery drains completely overnight even when the handset is sitting in the base — what causes that?

This is almost always a seating issue rather than a battery fault. The Kirk base cradle charges through metal contact pads — if the handset is even slightly off-centre, the circuit stays open and the handset runs on battery power all night instead of mains. Press the handset down firmly until you feel it click into the cradle seat and confirm the charge indicator light activates within thirty seconds of placing it.

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