ACE Caracas Replacement Battery 3.7V 1500mAh Li-ion

ACE Caracas / Caracas 2 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1500mAh Li-ion cell (5.55Wh) for the ACE Caracas and Caracas 2 smartphones. It fits both models using the same connector and voltage rail. Install it when the original cell no longer holds charge or the phone shuts down unexpectedly.

• Caracas and Caracas 2 fit: Both models share the same battery bay dimensions (65.80 × 43.90 × 5.10mm), connector pinout, and 3.7V supply rail — one cell covers both variants without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS held cutoff correctly at both ends, and charge acceptance was consistent across multiple cycles with no thermal anomalies.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one full 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 counter — preventing erratic percentage readings from the start.

Sudden shutdown at 20–30% on a new replacement cell

A fresh cell can trigger shutdowns well above 0% because the phone's fuel gauge IC is still calibrated to the old cell's discharge curve. When the modem or display draws a spike of current, the new cell's voltage dips briefly below the shutdown threshold — even though capacity remains. The phone reads that dip as empty and cuts out. One complete discharge-to-cutoff followed by a full charge resets the coulomb counter and resolves this. After that cycle, the gauge tracks the replacement cell accurately.

Phone feels warm near the battery during the first few charges

A new Li-ion cell starts with slightly higher internal impedance than a cell that has been cycled. The charge IC on the Caracas compensates by running a little harder, which produces modest heat at the battery. This is normal for the first two to three charges and settles as impedance drops with cycling. If the phone stays hot after the third full charge, check that the back cover is seated correctly — trapped heat from a loose cover will persist well beyond break-in.