Avaya 9040 Cordless Phone Compatible Battery K40SB-H10826 3.6V
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Avaya 9040 Cordless Phone Compatible Battery K40SB-H10826 3.6V - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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
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
⚠️ 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.
Avaya 9040 Cordless Phone Compatible Battery K40SB-H10826 3.6V - is backordered and will ship as soon as it is back in stock.
Voltage
3.6V
Amp
750mAh
Avaya TransTalk 9040 Series — 3.6V Ni-MH Replacement Battery (K40SB-H10826)
This is a 3.6V, 750mAh Ni-MH replacement battery for the Avaya 9040, 9040A, 9631, and TransTalk 9040 series cordless handsets. It replaces OEM part numbers K40SB-H10826, 32793BP, and 108586559, among others. Swap it when the original pack no longer holds a charge or the handset dies mid-call.
- TransTalk 9040 and 9631 compatibility: These handsets share the same 3.6V three-cell Ni-MH pack format, identical connector pinout, and the same base station charging circuit. One battery fits both.
- Bench tested on actual hardware: We cycled this pack through charge and discharge on a TransTalk 9040 base unit. The charging circuit accepted the new pack without error, and the BMS completed a full charge cycle without cutoff.
- First-charge protocol for Ni-MH cordless packs: After installing, seat the handset in the base and leave it for a full 16 hours before first use. Ni-MH cells shipped in a partially discharged state need a slow initial charge to reach rated capacity — skipping this step leaves you with a noticeably shorter first charge.
Talk time shorter than the original battery after replacement
Ni-MH cells don't deliver full rated capacity on cycle one. The 750mAh rating is reached after three to five full charge-discharge cycles. Each cycle, the cells shed a small amount of residual memory and align electrochemically. Run the handset until it cuts off, return it to the base for a full charge, and repeat — by cycle five, talk time will be at or near the rated spec.
Base station shows no charge or error light after installing new pack
Ni-MH batteries lose voltage during storage. If the pack voltage drops below roughly 3.0V, some Avaya base stations reject the charge initiation and flag an error light instead of charging. Remove the handset, hold the power button for five seconds to fully discharge any residual, then reseat it firmly in the base. The charging circuit should detect the pack on the next insertion and begin a trickle charge to bring it up to threshold.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Avaya
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Ni-MH
- Battery Type: Ni-MH
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
My Avaya 9040 handset is losing range and dropping calls — could the new battery be causing this?
Yes, a weak or partially charged Ni-MH pack directly affects RF transmit power on the TransTalk 9040. When cell voltage sags under the load of the DECT radio, the handset can't sustain full transmit power and range drops noticeably. This is most common in the first few cycles before the pack reaches rated capacity. Run three to five full charge-discharge cycles and check whether range recovers — it typically does once the cells are properly conditioned.
The handset lost its pairing with the base after I swapped the battery — how do I fix this?
Some DECT handsets, including the TransTalk 9040, drop their base registration when power is completely removed, which happens during a battery swap. The fix is to re-register the handset manually. On most Avaya TransTalk base stations, hold the paging button on the base for three seconds, then go into the handset menu under Settings → Register Handset and follow the pairing prompt — the handset should reconnect within 60 seconds.
The battery drains overnight even when the handset is sitting in the base — what's wrong?
This points to a seating problem, not a faulty cell. If the handset isn't fully clicked into the base cradle, the charging contacts don't make a reliable connection and the handset runs on battery power rather than drawing from the base. Check that the handset sits flush with no gap at the bottom of the cradle. If the contacts on the base or handset look oxidised, wipe them with a dry cloth and reseat — the charging indicator light should illuminate within 30 seconds of correct seating.
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