Sharp SH8188U EA-BL30 Replacement Battery 3.7V 1450mAh

Sharp SH8188U — 3.7V Li-ion Replacement Battery (EA-BL30)

The EA-BL30 is a 3.7V lithium-ion cell rated at 1450mAh (5.37Wh), built to fit the Sharp SH8188U smartphone. It replaces the original battery when capacity has dropped enough to cause shutdowns, swelling, or failure to hold charge. Fitting it restores full phone function without replacing the handset.

• SH8188U cell match: The SH8188U uses a single-cell 3.7V Li-ion pack with a specific connector orientation and BMS handshake tied to the charge IC on the motherboard. The EA-BL30 matches that voltage rail and connector, so the phone's charge IC recognises the cell and allows normal charge and discharge cycles.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a bench rig, monitoring BMS cutoff behaviour at both the low-voltage floor and the top-of-charge ceiling. The cell held within spec across multiple cycles, and the BMS did not trigger spurious lockout during motor-class current spikes from the modem or display backlight.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — preventing early percentage errors or false full readings.

Sudden shutdown at 20–30% on the replacement cell

A new cell swap can expose a mismatch between the fuel gauge IC's stored discharge curve and the actual voltage behaviour of the replacement cell. When the SH8188U's modem fires during a call or data burst, it pulls a sharp current spike. If the fuel gauge is reading against the old cell's curve, the real cell voltage can dip below the BMS cutoff threshold while the display still shows 25%. The phone shuts down to protect the cell, even though percentage appears safe. One full discharge-charge cycle without fast charging resets the coulomb counter and corrects the curve — after that, shutdowns at mid-percentage typically stop.

Phone warm near the battery during the first few charges

A fresh cell arrives with slightly higher internal impedance than a broken-in cell. During the first two or three charge cycles, the SH8188U's charge IC pushes current into that higher impedance, which converts more energy to heat than usual. This is normal and tapers off as the cell cycles in. If warmth continues past the third full charge cycle or the phone becomes hot to the touch rather than just warm, check that the battery connector is fully seated — a partial connection increases resistance and sustains the heating.