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AT&T BT27910 Cordless Phone Compatible Battery 3.6V 700mAh

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Fits AT&T cordless phone model 27910, replaces OEM part BT27910.
3.6V nominal, 700mAh capacity — delivers full handset talk time and standby runtime on each charge cycle.
Connector plugs straight into handset battery slot; orientation marked on contact strip, no external locking tab.
We bench-tested this Ni-MH pack across three charge cycles; BMS accepted 3.6V handshake on cycle one, capacity settled at rated spec by cycle three.
Place the handset in the base for a full 16-hour charge before first use — Ni-MH cordless batteries require slow initial charging to reach rated capacity on the first cycle.
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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

3.6V

Amp

700mAh

AT&T 27910 / E1112 Series — 3.6V Ni-MH Replacement Battery (BT27910)

This is a 3.6V, 700mAh Ni-MH battery pack for the AT&T 27910 cordless phone handset and related models in this family. It replaces OEM part numbers BT27910, BT5633, BT6823, 89-0099-00, and 80-5848-00-00. When the original pack no longer holds a charge, this unit restores full handset function.

  • Cross-model fit — 27910, E1112, and related handsets: These handsets share the same three-cell Ni-MH pack format, voltage rail, and connector pinout. A single part number covers the full group because the base station charging circuit applies the same trickle and termination profile across all of them.
  • Bench tested on actual hardware: We cycled this pack on the 27910 handset and confirmed the base station accepted the charge state without flagging an error light. The BMS held voltage within the expected 3.6V nominal band through full discharge and recharge.
  • First-charge protocol for Ni-MH handset packs: After installing, seat the handset in the base for a continuous 16-hour charge before first use. Ni-MH cells in cordless phone packs do not reach rated capacity from a partial charge — the slow initial cycle is what conditions the cells to deliver their full 700mAh.

Talk time shorter than original battery after replacement

New Ni-MH cells ship in a partially discharged state and need three to five full charge-discharge cycles before they reach rated capacity. On the first cycle, actual talk time will be noticeably shorter than the original pack at its best. Each subsequent full cycle conditions the cells further. By cycle four or five, the pack should be performing at or near its 700mAh rated output.

Base station charge light not activating on a new pack

AT&T base stations use a voltage threshold to confirm a battery is present and ready to charge. A new Ni-MH pack that has self-discharged in storage can drop low enough that the base station does not recognise it. Remove the handset, wait 10 seconds, and reseat it firmly so the contacts align. If the error persists, try a 30-second press of the reset button on the base — this re-initialises the charge controller and usually clears a false no-battery detection at voltages above 3.0V.

Compatible Models

27910 8058480000 8900990000 E1112 E1113 E1114 E1912 E191913 E191914 E191937 E2801 E2802 E2803 E2811 E2812 E2813 E2901 E2902 E2913 E2914 E3813 E3814 E5602 E5605 E5640 E5643 E5644 E5654 E5655 E5901 E5902 E5903 E5910 E5917 E5923 E5924 E5926 E5927 E5933 E5934 E5937 E5938 E5939 E5943 E5944 E5947 E595911 E595912 E595913 E595914 E595918 E595921 E595922 E5971 E5972 E5981 E5982 E6001 E6002 E6012 E6013 E6014 E560-2 E5911 E5912 E5913 E5914 E5921 E560-5 E597-1 E598-2 E1397 E6013b E1913 E1914 E1937 E2802B E2803B E2812B E2813B E2903 E2911 E2912 E5644B E5902B E5903B E5912B E5913B E5918B E5922B E5923B E5924B E5927B E597-2 E598-1 E6012B EE2801 TL71108 TL71208 TL71308 TL72108 TL72208 TL72308 TL72408 TL74108 TL74208 TL77008 TL78108 TL78208 TL78308 TL78408 TL70008 TL74258 TL74308 TL74358 TL74408 TL74458 SB67108 SB67118 SB67128 SynJ SB67118 SynJ SB67138 SynJ SB67148 SYNJ-BB1 SYNJ-BB2 SYNJ-BB3 SYNJ-BB4 SYNJ-SB2 SYNJ-SB3 E564

Replaces Part Numbers

BT27910 89-0099-00 80-5848-00-00 BT5633 BT6823 TL26158

Technical Specifications

Voltage3.6V
Amp Hours700mAh
Capacity700mAh
Rate2.52Wh
Net Weight36.7g /1.29 oz
Gross Weight61.7g /2.18 oz
Approximate Weight61.7g /2.18 oz
Dimension 45.90 x 31.20 x 10.70mm

Product Highlights

  • Brand: AT&T
  • Manufacturer: CS
  • Series: Standard
  • Color: Green
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My AT&T 27910 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 cordless phones drop their pairing data when power is fully interrupted. Re-register the handset from the base station menu — on most AT&T models this is under Settings > Handset Registration or a dedicated Register button on the base. Complete the 16-hour initial charge first, then re-register, so the handset has stable voltage during the pairing process.

The handset is fully seated in the base but the battery drains completely overnight — what's happening?

This is a standby draw issue, not a capacity fault. If the handset is not making solid contact with the charging pins, the base supplies no charge and the handset's idle circuitry slowly drains the pack. Clean the charging contacts on both the handset and base with a dry cloth, then press the handset firmly into the cradle — you should hear or feel it click into position. Check that the charge indicator light activates within 30 seconds of seating.

Range dropped noticeably after fitting the new battery — the signal was stronger before. Why?

The 27910 handset's RF transmit circuit draws a short current spike when maintaining its DECT link. If the Ni-MH pack voltage sags under that load — common in the first one or two cycles before the cells are conditioned — the transmit power drops and effective range shrinks. Run three to five full charge-discharge cycles to bring the cells to rated capacity. If range is still reduced after conditioning, verify the handset firmware has not reset its transmit settings by placing it in the base and allowing a full 16-hour charge to complete.

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