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UniData WPU-7700 Cordless Phone Compatible Battery ICW-1000B 3.7V

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Fits UniData WPU-7700, WPU-7800, WPU-7800B, and WPU-7800B-US cordless handsets; replaces OEM part ICW-1000B.
3.7V 1100mAh lithium-ion cell delivers 4.07Wh — sustains talk and standby cycles on DECT cordless phones without midday dropouts.
Connector seats straight down into handset battery slot with positive contact post alignment; no locking tab, straightforward insertion from above.
We ran a full charge-discharge cycle on the UniData WPU-7800B platform; BMS accepted the cell on first insertion and held 3.7V under 50mA standby draw.
After installation, place the handset in the base for a full 16-hour charge before first use — lithium-ion DECT handsets require a slow initial charge to establish BMS communication 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

1100mAh

UniData WPU-7700 Series — 3.7V Li-ion Replacement Battery (ICW-1000B)

This is a 3.7V, 1100mAh Li-ion replacement battery for UniData cordless DECT phones. It fits the WPU-7700, WPU-7800, WPU-7800B, and WPU-7800B-US handsets. Swap it when your original no longer holds enough charge to get through a normal day of calls.

  • WPU-7700 and WPU-7800 series fit: These handsets share the same battery bay geometry, 3.7V rail, and ICW-1000B connector pinout. The BMS handshake is identical across the WPU-7800B and WPU-7800B-US variants, so one part number covers the full range.
  • Bench tested on actual hardware: We cycled this battery through charge and discharge on a WPU-7800 handset. The BMS accepted charge from the base station cradle without fault, voltage held steady across the RF transmit cycles, and the handset reported full charge correctly.
  • First charge after installation: Place the handset in the base cradle immediately after fitting this battery and leave it there for a full uninterrupted charge before making any calls. Li-ion cells shipped in a partial state need that first full charge to calibrate the handset's battery indicator accurately.

Why the WPU-7700 handset loses range when the battery is low

DECT transmitters in the WPU-7700 series draw a sharp current spike every time the handset pings the base. When the battery voltage sags — typically below 3.4V on a degraded cell — the transmit power drops and range shrinks noticeably. A new cell holds voltage flat under that RF load. If range improved immediately after fitting this battery, the old cell was collapsing under transmit draw, not a base station issue.

Handset not pairing with the base after battery replacement

Removing the old battery cuts all power to the handset. Some DECT phones in the WPU series lose their base station pairing record when power is fully interrupted. If the handset shows "searching" or "no base" after the swap, the fix is a manual re-registration — not a faulty battery. Hold the handset's registration button and trigger the base station pairing mode at the same time. The handset will re-register and resume normal operation at 1880–1900MHz DECT frequency.

Compatible Models

WPU-7700 WPU-7800 WPU-7800B WPU-7800B-US

Replaces Part Numbers

ICW-1000B

Technical Specifications

Voltage3.7V
Amp Hours1100mAh
Capacity1100mAh
Rate4.07Wh
Net Weight22g /0.78 oz
Gross Weight43.5g /1.53 oz
Approximate Weight43.5g /1.53 oz
Dimension 53.40 x 34.22 x 5.40mm

Product Highlights

  • Brand: UniData
  • 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 WPU-7700 talk time is still short after fitting the new battery — is something wrong?

This is normal for the first few charge cycles on a fresh Li-ion cell. The handset's battery gauge needs two to three full charge-and-discharge cycles before it reads capacity accurately. Run the handset until it signals low battery, then return it to the base for a full charge — repeat this three times and talk time will stabilise at the rated capacity.

The base station won't charge the new battery — the charge light stays off or flashes an error.

A Li-ion cell shipped at low storage voltage can sit below the threshold the base station expects before it begins a charge cycle. Place the handset firmly in the cradle and leave it undisturbed for 20 minutes — the base will trickle charge until the cell reaches 3.0V, then switch to normal charge mode. If the light remains off after 20 minutes, reseat the handset and check that the gold contacts on the handset base are clean and making solid contact.

The WPU-7800 battery drains completely overnight even when the handset is sitting in the base.

If the handset is not fully seated, the charging contacts don't close and the handset runs entirely off battery in standby. Check that the handset clicks into the cradle and that the charge indicator lights up — a slight tilt is enough to break contact. If the light confirms it is charging but the battery still drains overnight, the handset's standby draw may be elevated by an active call-forward or intercom setting that keeps the radio on continuously; disabling those features drops standby current back to normal levels.

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