About this replacement
Coolpad S100A Series — 3.7V Li-ion Replacement Battery (CPLD-36)
This is a 3.7V, 800mAh Li-ion battery carrying OEM part number CPLD-36. It fits the Coolpad S100A, S116, E28, and F650, among others. Install it when the original cell no longer holds a charge or the phone shuts down unexpectedly under load.
- S100A, S116, E28, and F650 compatibility: These models share the same 3.7V nominal voltage rail, identical connector pinout, and a BMS handshake protocol that accepts the CPLD-36 cell without firmware flags or charge inhibition.
- Bench tested on actual hardware: We ran the CPLD-36 through full charge and discharge cycles on compatible hardware. The BMS accepted the cell immediately, held charge termination correctly at 4.2V, and triggered low-voltage cutoff at the expected threshold without premature shutdowns.
- Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge down to automatic shutoff, then charge uninterrupted to 100%. This gives the fuel gauge IC one full cycle to map the new cell's discharge curve before high-current charging begins on an uncalibrated cell.
Why the Coolpad S100A shuts down suddenly at 20–30% after a cell swap
A new cell has a slightly different internal resistance profile than the aged cell the fuel gauge IC was calibrated against. Under modem transmission or screen load, current draw spikes and voltage drops faster than the IC predicts — the phone hits the hardware cutoff before the percentage counter reaches zero. This isn't a fault in the replacement cell. One full discharge-charge cycle recalibrates the coulomb counter to the new cell's actual discharge curve, and the premature shutdowns stop.
Phone shows incorrect battery percentage after installing the CPLD-36
The fuel gauge IC stores a learned discharge model from the original cell. When you swap in a new cell, that model is mismatched — the percentage reading drifts, jumps, or stalls at a fixed value. Force a full recalibration: drain the phone to automatic shutdown, then charge in one uninterrupted session to 100% with the screen off where possible. After one complete cycle, the IC rebuilds its model against the new cell and percentage reporting stabilises to within a few percent of actual charge state.