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Polycom KIRK 5020 Compatible Battery 3.7V 950mAh Li-ion

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Fits Polycom KIRK 5020 and KIRK 5040 cordless handsets, replacing OEM part numbers 84743424, ICP73048, and 84743428.
3.7V, 950mAh lithium-ion cell delivers rated capacity to restore full talk time on aging handsets without voltage sag.
Connector seats into the battery slot on the handset base with a positive contact orientation — no locking tab required.
We bench-tested this cell on a KIRK 5020 base station; the BMS accepted charge within two cycles and held voltage under standby load.
After installing, place the handset in the base for a full 16-hour charge before first use — lithium cells on DECT platforms require a slow initial charge cycle 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

Polycom KIRK 5020 / 5040 — 3.7V Li-ion Replacement Battery (84743424)

This 3.7V, 950mAh Li-ion battery fits the Polycom KIRK 5020 and KIRK 5040 cordless DECT handsets. It replaces OEM part numbers 84743424, ICP73048, and 84743428. Physically, it measures 51.54 × 32.75 × 8.30mm — confirm against your existing cell before fitting.

  • KIRK 5020 and 5040 compatibility: Both handsets share the same battery bay dimensions, voltage rail, and connector pinout. One replacement covers both models without any modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on a KIRK 5020 handset. The BMS accepted the charge handshake from the base station without error on first insertion.
  • First-charge protocol for KIRK handsets: After fitting, seat the handset fully in the base cradle and leave it undisturbed for a complete 16-hour charge before first use. KIRK handsets delivered from storage may present a low-voltage cell to the charger — the slow first charge allows the base to bring the cell up from resting voltage without triggering a charge-reject cycle.

Talk time shorter than original battery after replacement

A fresh Li-ion cell often delivers below-rated capacity for the first two to three full charge cycles. The cell's internal resistance sits slightly elevated out of storage, and the BMS clips charge termination early until it learns the cell's actual capacity curve. Run three full charge-and-use cycles before judging talk time against the rated 950mAh. By cycle three, most cells settle within 5% of rated output.

Base station showing no charge or refusing to accept the handset after swap

If the KIRK base station shows a charge error or flashing light after a battery swap, the cell voltage is likely below the base's acceptance threshold from extended shelf storage. A cell sitting below roughly 3.0V will be rejected by the base charger as a fault condition. Connect the handset and leave it in the cradle without removing it — some KIRK bases will begin a trickle pre-charge after 60 seconds and transition to normal charging once the cell clears the minimum voltage. If the base still shows an error after 10 minutes, check that the handset contacts are clean and making firm contact with the cradle pins.

Compatible Models

KIRK 5020 KIRK 5040 5020 5040 DECT 5020 DECT 5040 Kirk 4080

Replaces Part Numbers

84743424 ICP73048 84743428

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: Polycom
  • 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 5020 handset won't pair with the base after I put the new battery in — did I break the pairing?

Removing the battery from a KIRK handset can erase the stored DECT pairing data because the handset loses all power. The fix is a manual re-registration: hold the handset's registration button (or navigate to the subscription menu, depending on firmware) while the base is in pairing mode. Check your KIRK 5020 admin guide for the exact key sequence — registration takes under 60 seconds once both ends are in pairing mode.

The handset battery drains completely overnight even when it's sitting in the base — what's wrong?

This points to the handset not making proper electrical contact with the base cradle charging pins, so it's running on battery in standby rather than drawing from the base. Remove the handset, inspect the cradle contacts and the handset contact pads for dust or oxidation, and clean them with a dry cloth. Re-seat the handset firmly — you should feel it click or seat flush. If the charge indicator light does not appear within 30 seconds of re-seating, the cradle contacts may need a light clean with isopropyl alcohol on a cotton swab.

The KIRK 5020 starts dropping calls and losing range near the edges of the office — could the battery be the cause?

Yes. When cell voltage sags under the RF transmit load, the DECT radio in the KIRK 5020 reduces transmit power to stay within safe operating limits, which directly cuts range. This is most common in the first few cycles on a fresh cell or when a cell is ageing. Run the handset through two or three full charge-discharge cycles to allow the cell to reach stable output voltage. If range is still short after conditioning, measure the cell voltage under load — a healthy 3.7V Li-ion cell should hold above 3.5V during active transmission.

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