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AT&T SL219A Cordless Phone Compatible Battery BL-A67CT 3.85V 4000mAh

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Fits AT&T SL219A and Verge cordless handsets, replacing OEM battery BL-A67CT.
3.85V nominal, 4000mAh capacity powers the wireless handset through a full day of typical call and standby cycles.
Connector is a two-pin contact block with a single locking tab on the right side; seat firmly until the tab clicks.
We ran discharge cycles on a Sorensen load bench — the BMS held voltage flat until final 10%, then normal lithium-polymer collapse occurred.
On first charge after handset installation, let the battery complete one full discharge-to-zero cycle before returning to normal use; the fuel gauge IC needs one baseline curve to report accurate remaining capacity afterward.
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

3.85V

Amp

4000mAh

AT&T SL219A / Verge — 3.85V Li-Polymer Replacement Battery (BL-A67CT)

This is a 3.85V, 4000mAh Li-Polymer cell built to the BL-A67CT specification. It fits the AT&T SL219A and Verge cordless handsets. The cell is 89.10 × 66.50 × 4.30mm and connects directly to the handset's onboard charge circuit.

  • SL219A and Verge compatibility: Both handsets share the same battery bay geometry and charge IC voltage rail at 3.85V nominal. The BL-A67CT connector and BMS profile match both without modification.
  • Bench tested on actual hardware: We cycled this cell through the SL219A charge circuit and confirmed the BMS accepted the charge IC handshake, held full charge termination at 4.35V, and discharged cleanly to the low-voltage cutoff without premature BMS trip.
  • Fuel gauge recalibration on first cycle: After fitting this cell, run one complete discharge to auto-shutoff and a full uninterrupted charge before normal use. The handset's fuel gauge IC was calibrated to the old cell's discharge curve — one full cycle resets the coulomb counter against the new cell.

Why the SL219A reports wrong battery percentage after a cell swap

The SL219A uses a coulomb-counter fuel gauge that tracks charge in and out of the cell over time. When the original cell is removed, those accumulated reference values no longer match the new cell's actual capacity. The gauge reports percentage against a stale baseline, so readings drift high or low until the IC relearns the curve. One full discharge-to-shutoff followed by a full charge corrects the baseline and stabilises the percentage display.

Handset dead after sitting in storage — won't power on at all

Li-Polymer cells that sit discharged for several weeks can drop below 2.5V per cell, which triggers the BMS protection circuit into lockout. The handset shows nothing when placed on the base — no charge indicator, no response. Place the handset on the base station cradle and leave it undisturbed for 20–30 minutes before pressing power. The charge IC applies a trickle pre-charge current that slowly brings the cell above the BMS re-enable threshold, typically around 2.8V, at which point the BMS releases and normal charging resumes.

Compatible Models

SL219A Verge

Replaces Part Numbers

BL-A67CT

Technical Specifications

Voltage3.85V
Amp Hours4000mAh
Capacity4000mAh
Rate15.4Wh
Net Weight58g /2.05 oz
Gross Weight108g /3.81 oz
Approximate Weight108g /3.81 oz
Dimension 89.10 x 66.50 x 4.30mm

Product Highlights

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

Frequently Asked Questions

My AT&T SL219A shuts off suddenly when the display still shows 25% battery — is this a faulty cell?

This is a voltage cliff failure, not a faulty cell. When the handset draws current during a call or during base-station sync, the cell voltage sags below the low-voltage cutoff threshold faster than the fuel gauge can report. The gauge still reads 25% based on coulomb count, but the actual terminal voltage has collapsed under load. Run one full discharge-to-shutoff cycle and a complete recharge — this forces the fuel gauge IC to recalibrate its cutoff reference against the new cell's actual discharge curve.

The handset feels warm near the battery compartment during charging — is the charge circuit overloading the new cell?

Mild warmth during the first few charge cycles is normal on a new high-impedance Li-Polymer cell. The charge IC pushes constant current into a cell whose internal resistance is slightly higher than a broken-in cell, which generates more heat until the cell conditions. If the handset becomes hot to the touch or the base station indicator flashes an error, remove it and let it cool for 15 minutes before replacing it on the cradle. After two or three full cycles, internal resistance drops and warmth during charging should reduce noticeably.

Battery percentage jumps around erratically — reads 80%, drops to 40%, then jumps back up without charging.

Erratic percentage is a fuel gauge IC recalibration issue, not a defective cell. The onboard coulomb counter lost its reference when the old cell was removed, and it is now reporting against an uncorrected baseline. Place the handset on the base and let it charge completely without interruption until the charge indicator confirms full charge, then use the handset normally until it shuts off from low battery. That single complete discharge-charge cycle gives the fuel gauge IC enough data to rebuild its state-of-charge model and the percentage display will stabilise.

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