ViewSonic Q3 Li47180bk Replacement Battery 3.7V 1800mAh

ViewSonic Q3 / Q5 / Q1 Series — 3.7V Li-ion Replacement Battery (Li47180bk)

This is a 3.7V, 1800mAh lithium-ion cell replacing the original Li47180bk battery in ViewSonic Q3, Q5, Q1, and Q3+ smartphones. It fits the same footprint at 63.80 × 39.20 × 6.90mm and connects to the same charge IC these phones use. Capacity is 6.66Wh, matching the stock spec.

• Q-series model compatibility: The Q1, Q3, Q3+, and Q5 share the same battery bay dimensions and connector pinout. ViewSonic used one battery platform across this range, so Li47180bk slots into any of them without modification.
• Bench tested on actual hardware: We cycled this cell through a full discharge-charge sequence and monitored the BMS for cutoff behaviour. Charge termination triggered correctly at 4.2V and low-voltage cutoff engaged before the cell reached unsafe depth.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one complete discharge down to auto-shutoff, then charge to 100% on standard current. This gives the phone's fuel gauge IC one clean cycle to map the new cell's discharge curve before fast charge pushes higher current into an uncalibrated cell.

Why the Q3 shuts down suddenly at 20–30% after a battery swap

The Q3's fuel gauge IC stores a discharge curve from the old cell. When a new cell with a slightly different internal resistance replaces it, the voltage-to-percentage mapping is wrong. Under load — screen on, mobile data active — voltage drops faster than the gauge predicts, and the phone hits the hardware undervoltage floor before the OS registers low battery. One full discharge-to-shutoff cycle followed by a full charge corrects the coulomb counter and eliminates false shutdowns.

Phone shows incorrect battery percentage after installing a new cell

The fuel gauge IC on these ViewSonic phones uses a learned model of the cell's capacity, built up over many charge cycles on the original battery. A replacement cell resets that learned state, so percentage readings jump or stall — commonly showing 100% for long periods or dropping 10% in seconds. The fix is straightforward: let the phone discharge fully until it powers off, then charge uninterrupted to 100% without using the device. After that single calibration cycle, percentage tracking stabilises against the new cell's actual capacity.