Pentax R100 BP02C Replacement Battery 6V 4200mAh

Pentax R100 / R200 / R300 Series — 6V Ni-MH Replacement Battery (BP02C)

This is a 6V, 4200mAh Ni-MH replacement for the Pentax BP02C battery pack. It fits the R100, R200, R300, and R-100X surveying instruments, plus several additional R-series models. Voltage and capacity match the original specification exactly.

• R-series instrument compatibility: The R100 through R300 line shares the same battery bay geometry, connector pinout, and 6V supply rail. The BMS in each instrument reads cell voltage directly — no proprietary authentication handshake — so a correctly specced Ni-MH pack slots in without firmware issues.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the bench, monitoring cell voltage under the sustained sensor load the R-series draws during active distance measurement. The BMS handled low-voltage cutoff cleanly with no false trips on initialisation.
• Pre-deployment calibration cycle: After fitting this pack, run a full calibration sequence through the instrument menu before heading to site. The R-series maps battery state during calibration — skip this step and the instrument will throw premature low-battery warnings on your first measurement session, even with a fully charged pack.

Why an R-series instrument shuts down the moment the distance sensor initialises

The EDM module in the R100 and R200 draws a short current spike when it powers up the laser emitter circuit. A degraded or partially discharged Ni-MH pack can't sustain voltage through that spike, and the instrument's undervoltage protection trips before a single reading is taken. This is not a fault in the instrument — it's the BMS doing exactly what it should. A fresh, fully charged pack delivers the transient current without the voltage rail collapsing. If shutdowns happen immediately on trigger, check pack voltage at rest before assuming the instrument is faulty.

Pack will not charge and instrument shows no power after months in storage

Ni-MH cells self-discharge over time. If the R-series pack sat unused in a carry case for several months, individual cells may have dropped below the threshold the charger needs to detect and begin a charge cycle — the charger simply sees no valid cell response and does nothing. Connect the pack to the Pentax charger and hold it there for at least 15–20 minutes even if no charging indicator appears; most chargers apply a low trickle to recover cells from this state before switching to normal charge. If the pack still shows no response after 30 minutes, measure the pack voltage directly — a reading below 3.0V across a 6V Ni-MH pack indicates cells that will not recover.