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SpectraLink S33 DECT Replacement Battery 3.7V 1200mAh

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New arrival
From $38.99 USD $47.99
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Fits SpectraLink S33 and S33 DECT handsets, replaces OEM part 84743430.
3.7V, 1200mAh lithium-ion cell restores full handset talk time and standby duration.
Connector slides into battery slot on handset rear; no locking tab present.
We bench-tested the pack on a paired S33 base — BMS accepted charge immediately.
After installing, seat the handset in base for a full 16-hour first charge.
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.

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⚠️ 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 S33 DECT Handset — 3.7V Li-ion Replacement Battery (84743430)

This 3.7V, 1200mAh lithium-ion battery replaces the original pack in the SpectraLink S33 and S33 DECT handset. It fits the cordless DECT handset directly, restoring power to the unit when the original cell has degraded after repeated charge cycles. OEM part numbers 84743430 and BT229865 both apply to this handset.

  • S33 and S33 DECT handset fit: Both model variants share the same battery bay dimensions and connector pinout — 53.20 × 34.00 × 5.50mm — so one cell covers the full S33 range without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on a DECT handset platform. The BMS held the 3.7V nominal rail steady and tripped protection only at the low-voltage floor — no premature cutoff under RF transmit load.
  • First installation charging tip: Seat the handset in the base for a full charge before first use. Li-ion cells shipped in partial-charge storage state may register low on the handset's fuel gauge until one full charge cycle completes.

Talk time shorter than rated after installing the new battery

A freshly installed Li-ion cell coming out of storage is rarely at full calibration with the handset's fuel gauge circuit. The handset reads state-of-charge based on voltage curves, and a cell that hasn't completed a full cycle yet will report capacity low. Run one full charge from the base, then use the handset until it powers off from low battery. Recharge fully — after that cycle, the gauge reading stabilises against the actual cell capacity.

Base station shows no charge or error light after battery swap

Some SpectraLink base units check incoming voltage before enabling the charge circuit. A cell shipped at storage voltage — typically 3.5V or below — can fall under the base's acceptance threshold, causing the charge LED to stay dark or show a fault. Place the handset in the base and leave it undisturbed for 15–20 minutes. The base trickle-charges the cell up to the threshold, then switches to normal charge mode. If the light still won't change, confirm the handset contacts are clean and fully seated.

Compatible Models

S33 S33 DECT S33 DECT Handset

Replaces Part Numbers

84743430 BT229865

Technical Specifications

Voltage3.7V
Amp Hours1200mAh
Capacity1200mAh
Rate4.44Wh
Net Weight23g /0.81 oz
Gross Weight48g /1.69 oz
Approximate Weight48g /1.69 oz
Dimension 53.20 x 34.00 x 5.50mm

Product Highlights

  • Brand: SpectraLink
  • 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 SpectraLink S33 handset lost its pairing with the base after I swapped the battery — how do I get it back?

Removing the battery cuts all power to the handset, and some DECT phones drop their pairing data when power is fully lost. The base and handset need to re-register. Put the handset on the base to charge first, then follow the SpectraLink S33 DECT registration procedure — hold the handset's paging or registration button until the base LED flashes, then confirm on the handset. Once paired, the handset retains the registration even through future battery swaps as long as the base stays powered.

The S33 handset battery drains completely overnight even while it's sitting on the base — what's wrong?

This points to the handset not making proper contact with the base charging pins rather than a battery fault. If the handset is slightly tilted or the contacts are dirty, it sits in the cradle but draws no charge current — it runs on battery the entire time. Wipe the gold contacts on both the handset and base with a dry cloth, reseat the handset firmly, and check that the charge LED activates. A correctly docked S33 draws from the base and leaves the cell at full voltage by morning.

The S33 handset range seems shorter than it was with the original battery — is that a battery problem?

Yes, voltage sag under RF load is the most common cause. When the cell voltage drops during a transmit burst, the handset's RF front end gets less power and reduces output to stay within operating limits — which cuts usable range. This is most noticeable when the battery isn't fully charged. Charge the handset fully to 3.7V nominal, then test range again. If range improves at full charge but drops off quickly, the cell may need one more full cycle to reach rated capacity after storage.

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