Samsung Galaxy S Relay 4G EB-L1K6ILA Replacement Battery 3.7V 1800mAh

Samsung SGH-T699 / Galaxy S Relay 4G — 3.7V Li-ion Replacement Battery (EB-L1K6ILA)

This 3.7V 1800mAh Li-ion cell replaces the original EB-L1K6ILA in the Samsung SGH-T699 (Galaxy S Relay 4G). It also fits the Galaxy S Blaze Q and SCH-i415. Dimensions are 69.80 × 51.90 × 4.20mm — same footprint as the factory cell.

• SGH-T699 / Relay 4G / Blaze Q platform fit: These models share the same battery bay geometry, connector pinout, and BMS handshake protocol. One cell covers the full group without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Relay 4G unit. The BMS accepted the charge profile on the first cycle, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first installation, disable fast charging and run one full discharge-to-charge cycle before normal use. The fuel gauge IC on the Relay 4G calibrates its coulomb counter against the cell's discharge curve — skipping this step causes the percentage readout to drift against the new cell's actual capacity.

Sudden shutdown at 20–30% on the Relay 4G after a cell swap

The SGH-T699 shuts down abruptly at 20–30% when the modem fires a high-current burst — LTE radio and the screen backlight pulling load simultaneously can spike demand beyond what a new, uncalibrated cell can hold up under. This is a voltage cliff event: the cell's terminal voltage drops below the system's cutoff threshold faster than the fuel gauge predicts. The gauge IC is still reading the old cell's discharge curve and calling 25% when the new cell is actually near depletion under load. One full discharge-to-charge cycle recalibrates the coulomb counter and resolves this.

Phone won't power on after the replacement cell sat in storage

Li-ion cells self-discharge during storage, and if the replacement cell dropped below 2.5V per cell, the BMS latches into lockout to prevent damage. The phone will show nothing — no charging animation, no boot screen. Connect the phone to a wall charger (not a USB port) and leave it for 15–20 minutes without pressing power. The charge IC on the Relay 4G can trickle current into a locked-out cell and release the BMS latch once voltage climbs back above 2.7V, after which the phone will begin a normal charge cycle.