About this replacement
Casio Exilim EX-S200 Series — 3.7V Li-ion Replacement Battery (NP-120)
This is a 3.7V, 550mAh Li-ion cell built to the NP-120 spec. It fits the Casio Exilim EX-S200, EX-S200BK, EX-S200BE, and related Exilim compact models. If your original NP-120 no longer holds a charge, this cell swaps directly into the same battery compartment.
- EX-S200 series compatibility: These Exilim models share the same 3.7V battery rail, NP-120 form factor, and BMS handshake protocol. One cell covers the full range listed without modification.
- Bench tested on actual hardware: We cycled this cell through the EX-S200 body and an OEM Casio charger. The BMS accepted the cell on first insertion, voltage regulation held steady through full discharge, and capacity read correctly at 550mAh.
- First-cycle initialisation on the EX-S200: Run the first full charge through the camera body or OEM Casio charger rather than a third-party USB adapter. Some Exilim BMS firmware maps the battery-remaining indicator during this first charge cycle — skipping it can cause percentage display drift through the cell's early life.
Battery percentage jumping on the EX-S200 display after installing a new NP-120
The Exilim EX-S200 maps its battery indicator against the discharge curve of the original NP-120 cell. A new cell's discharge curve doesn't always align with the camera's stored voltage thresholds until it has completed at least one full charge-discharge cycle. This mismatch causes the indicator to jump — for example, showing 60% then dropping to 20% without warning. Run two full charge-to-empty cycles in the camera body to let the BMS recalibrate its threshold mapping. After that, the indicator stabilises against the new cell's actual curve.
Flash not fully recycling between shots near end of charge
The EX-S200's flash capacitor pulls a high recharge current immediately after each shot. When cell voltage drops below roughly 3.5V, that recharge current causes a brief voltage sag that the BMS registers as a low-power condition. The camera either delays the next shot or fires an undercharged flash, producing noticeably dimmer output. This isn't a faulty cell — it's the BMS protecting the circuit. Recharge the battery before the indicator reaches one bar to keep flash recycling at full output.