Elson EL400 Replacement Battery 3.7V 1500mAh BTY26170

Elson EL400 — 3.7V Li-ion Replacement Battery (BTY26170)

This is a 3.7V, 1500mAh Li-ion cell for the Elson EL400 and Mobistel EL400 smartphone. It replaces OEM part BTY26170 and BTY26170/STD directly. Fit the cell when the original no longer holds a usable charge or fails to power the phone at all.

• EL400 and Mobistel EL400 compatibility: Both variants share the same physical housing, connector pinout, and BMS handshake protocol — a single cell covers both. The 66.00 × 43.50 × 5.00mm footprint matches the factory battery bay without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the EL400 platform. The BMS communicated charge state correctly to the phone's fuel gauge IC, and the protection circuit tripped at the expected low-voltage threshold without requiring a manual reset.
• First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before any high-current charging session begins — skipping this step is why percentage readings jump around in the first day.

Sudden shutdown at 20–30% on the EL400 after a cell swap

The EL400's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, the stored curve no longer matches actual cell voltage under load. The modem or display draws a spike of current, voltage drops below the BMS cutoff threshold faster than the gauge expects, and the phone shuts off while still showing 20–30%. One full discharge-charge cycle recalibrates the coulomb counter and eliminates the early cutoff on most units.

Phone won't power on after sitting in storage — BMS lockout on deep discharge

If the EL400 or a stored replacement cell has sat unused for several months, the cell voltage may have dropped below 2.5V — the threshold at which the BMS locks out to prevent damage to the lithium cells. The phone will show nothing when you press the power button, and a standard charger may not push enough trickle current to wake the BMS. Connect the phone via USB to a wall adapter — not a PC port — and leave it for 20–30 minutes before attempting to power on; the charge IC needs a sustained low-current input to pull the cell back above the 3.0V recovery threshold.