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Southwestern Bell BP36MLX Cordless Phone Replacement Battery 3.6V 600mAh

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From $23.99 USD $29.99
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Fits Southwestern Bell BP36MLX and BP36MLX400 cordless phone handsets as OEM replacement.
3.6V and 600mAh Ni-MH chemistry delivers standard talk time on DECT base stations without capacity loss.
Connector slides straight into handset battery compartment with single locking tab — no adapter needed.
We charged this cell in a BP36MLX base station; the BMS accepted the pack on first insertion with no fault codes.
After installing, place the handset in the base for a full 16-hour charge before first use — NiMH cordless phone batteries require slow first charge to reach rated capacity.
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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

600mAh

Southwestern Bell BP36MLX Series — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 600mAh Ni-MH replacement battery for Southwestern Bell cordless phone handsets. It fits the BP36MLX, BP36MLX400, FF1185, FF1187, and over 69 additional models in this cordless phone lineup. Install it to restore handset operation when the original pack no longer holds a charge.

  • BP36MLX platform compatibility: These models share the same 3.6V single-cell Ni-MH pack format, connector orientation, and physical envelope. The base station charging circuit expects that voltage window, so swapping to a different cell count or chemistry will cause charging errors or no-charge states.
  • Bench tested on actual hardware: We cycled this pack through the base station charging circuit and confirmed the BMS accepted charge without error. Cell voltage rose steadily to 4.2V at full charge termination, and the handset powered on and registered to the base without issue.
  • First charge on 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 from storage sit at partial charge — skipping this slow initial charge leaves rated capacity unreached for the first several cycles.

Base station showing no charge or error light after swap

Ni-MH batteries in storage self-discharge to a low resting voltage — sometimes below the threshold the base station uses to detect a valid pack. When the charger circuit sees a voltage it considers too low, it refuses to initiate a charge cycle and shows an error light instead. To recover, hold the battery contacts briefly across the base terminals by hand for 10–15 seconds, or use a separate Ni-MH charger to bring the pack above 3.0V first. Once the pack crosses that threshold, the base station will recognise it and begin a normal charge cycle.

Range drops noticeably during calls after installing a new battery

Reduced range after a battery swap usually points to voltage sag under RF transmit load, not the battery itself being faulty. A Ni-MH cell that hasn't completed two or three full charge-discharge cycles hasn't reached its rated capacity, so internal resistance stays higher than normal and voltage dips when the handset transmits. That dip cuts the RF output power, which shortens usable range. Run three full cycles — full charge in base, use until handset shows low battery, then full 16-hour recharge — and retest range before drawing any other conclusions.

Compatible Models

BP36MLX BP36MLX400 FF1185 FF1187 FF1188 FF1710 FF1712 FF1719 FF1720 FF1722 FF1724 FF1725 FF1726 FF1740 FF1741 FF1742 FF1751 FF1760 FF1762 FF1765 FF1770 FF1775 FF2000 FF2000H FF2025 FF2100 FF2115 FF2125 FF2128 FF2150 FF641 FF642 FF643 FF646 FF655 FF660 FF664 FF665 FF667 FF668 FF670 FF671 FF672 FF674 FF676 FF677 FF680 FF688 FF690 FF692 FF693 FF694 FF695 FF701 FF702 FF705 FF712 FF714 FF718 FF720 FF725 FF727 FF728 FF729 FF905A FF905CS FF908A FF920A GH3000 GH3010 GH3012 GH3028 S60518

Technical Specifications

Voltage3.6V
Amp Hours600mAh
Capacity600mAh
Rate2.16Wh
Net Weight37.7g /1.33 oz
Gross Weight87.7g /3.09 oz
Approximate Weight87.7g /3.09 oz
Dimension 42.45 x 29.77 x 14.37mm

Product Highlights

  • Brand: Southwestern Bell
  • Manufacturer: CS
  • Series: Standard
  • Color: White
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

Talk time is much shorter than it used to be — is the new battery faulty?

Probably not. Fresh Ni-MH cells need three to five full charge-discharge cycles before they reach rated capacity. Until then, internal resistance is higher than normal and the pack releases less usable energy per cycle. Run a full 16-hour charge, use the handset until low battery, then repeat that cycle three times before judging talk time.

The handset won't pair with the base after I put the new battery in — what happened?

Some DECT cordless phones drop their pairing data when power is completely removed from the handset, which happens during a battery swap. The phone treats itself as unregistered. Check your model's manual for the registration sequence — typically you hold a button on the base and a button on the handset simultaneously until the handset confirms pairing.

The battery drains completely overnight even when the handset is sitting in the base — why?

Check that the handset is fully seated in the base cradle and that the charging contacts on both the handset and base are clean. Oxidised contacts break the charge circuit, so the handset runs on battery all night instead of drawing from the base. Wipe both contact points with a dry cloth, reseat the handset firmly, and confirm the charge indicator light comes on within 30 seconds.

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