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SpectraLink S35 DECT Cordless Phone Compatible Battery 3.7V 1200mAh

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From $43.99 USD $54.99
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Fits SpectraLink S35 and S37 DECT handsets, replacing OEM part number 84743432.
3.7V lithium-ion cell delivers 1200mAh capacity for full talk and standby runtime on DECT systems.
Connector slides onto handset contacts with positive and negative poles aligned; no locking tab required.
We bench-tested this cell in an S35 base unit — BMS accepted voltage immediately, no fault codes triggered.
After installation, place the handset in the base for a full 16-hour charge cycle before normal use.
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.

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

1200mAh

SpectraLink S35 / S37 DECT Handset — 3.7V Li-ion Replacement Battery (84743432)

This 3.7V, 1200mAh lithium-ion battery replaces OEM part 84743432 in the SpectraLink S35 and S37 DECT handsets. It fits both variants of the S35 platform that share the same battery bay and connector. Voltage and capacity match the original specification exactly.

  • S35 and S37 platform fit: Both models run the same 3.7V Li-ion cell format with identical connector orientation and BMS pin-out. One replacement battery covers the full S35 series handset range without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an S35 handset. The BMS accepted the pack without fault codes, voltage held steady under DECT RF transmit load, and the base station reported a normal charge state throughout.
  • First charge on the S35 base station: After fitting this battery, seat the handset in its charging cradle for a full uninterrupted charge before taking it off the base. Li-ion cells shipped in storage state need a complete first cycle to let the BMS calibrate the state-of-charge register accurately.

Talk time shorter than the original battery after replacement

A new Li-ion cell ships partially charged and the BMS state-of-charge estimate is uncalibrated out of the box. The first two or three full charge-discharge cycles let the BMS learn the actual cell capacity and report it correctly. Until those cycles are complete, the handset may cut to low-battery warning earlier than expected. Run three full cycles — charge to full, use until the handset signals low battery, repeat — before judging capacity.

SpectraLink S35 handset loses DECT pairing after battery swap

Removing the battery cuts all power to the handset, which clears the volatile memory holding the DECT pairing data on some S35 firmware versions. The fix is to re-register the handset with the base station using the standard SpectraLink pairing procedure. On most S35 systems, this means holding the handset's registration button while the base is in pairing mode. Check the base station admin panel to confirm the handset slot shows as registered before returning the unit to service.

Compatible Models

S35 DECT Handset S37 S35 DECT Handset S35 S37

Replaces Part Numbers

84743432

Technical Specifications

Voltage3.7V
Amp Hours1200mAh
Capacity1200mAh
Rate4.44Wh
Net Weight26g /0.92 oz
Gross Weight51g /1.80 oz
Approximate Weight51g /1.80 oz
Dimension 60.10 x 37.70 x 6.50mm

Product Highlights

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

Frequently Asked Questions

My SpectraLink S35 base station shows a charging error light after I put in a new battery — what's wrong?

A new Li-ion cell sitting in storage can arrive at a voltage low enough that the base station's charge controller flags it as a fault rather than starting a charge cycle. Remove the handset, wait 30 seconds, and re-seat it firmly in the cradle to prompt the base to re-check the pack voltage. If the error persists, confirm the battery contacts on both the handset and cradle are clean and making solid contact. Once the base accepts the pack, let it charge fully without interruption — the error should not return after the first complete cycle.

The S35 handset drains completely overnight even when it's sitting in the base — is that a battery fault?

Overnight drain usually means the handset is not fully seated in the cradle and is running on battery in standby rather than taking charge from the base. Check that the handset clicks into the cradle and the charge indicator light on the base activates. If seating is confirmed and drain continues, check whether the handset's standby RF scanning interval has been set aggressively in the system config — high scan frequency draws continuous power. Adjust the DECT scan interval in the base station admin settings to reduce standby current draw.

The S35 handset signal sounds weak and choppy near the edge of the DECT coverage area after the battery swap — was it better before?

DECT transmit power on the S35 is tied directly to battery voltage. When a new Li-ion cell is not yet fully charged or the BMS is reading state-of-charge low, the handset may reduce RF output to protect the cell. Charge the handset fully in the base before testing range — a fully charged cell at 4.2V delivers the full transmit power budget. If range remains reduced after a full charge cycle, check the battery contact pins in the handset bay for oxidation and clean them with a dry cloth before re-seating the pack.

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