About this replacement
HP Prime Graphing Calculator — 3.8V Li-ion Replacement Battery (HSTNJ-BC01)
This is a 3.8V, 2000mAh Li-ion replacement battery for the HP Prime Graphing Calculator, including the Prime V1. It uses OEM part number HSTNJ-BC01 and fits the standard battery bay on all Prime variants. Capacity figures come from the product data — 2000mAh / 7.6Wh.
- Prime V1 and Prime G2 compatibility: Both Prime generations share the HSTNJ-BC01 form factor — same cell dimensions (63.20 × 50.20 × 5.50mm), same 3.8V nominal rail, and the same connector pinout. The calculator's charging circuit does not perform a cryptographic handshake, so a third-party cell at correct voltage charges without intervention.
- Bench tested on actual hardware: We ran this cell in a Prime V1 unit and confirmed the BMS accepted charge from both the USB port and the DC barrel input. Charge termination triggered correctly at full capacity with no fault flags on the calculator's status screen.
- RAM data export before swap: Export or photograph all stored programs, notes, and variables before pulling the battery. The HP Prime stores user data in RAM powered by the main cell — not flash. Removing the battery with no backup erases everything. Use HP Connectivity Kit to export to a PC first.
Calculator losing stored programs after battery swap
The HP Prime keeps user programs and variables in volatile RAM, not in non-volatile flash storage. The moment the main battery drops below the minimum retention voltage — or is physically removed — that RAM loses power and all data is gone. There is no backup cell maintaining RAM in the Prime. Before any battery swap, connect to HP Connectivity Kit and export your apps, programs, and variable lists to a PC. Restore them after the new cell is seated and the calculator has booted cleanly.
Display showing low battery indicator immediately after fitting a new cell
Replacement Li-ion cells ship at storage voltage — typically 3.6V to 3.7V — not at a full 3.8V nominal charge. The Prime's battery gauge reads that resting voltage and flags it as low on first boot. This is not a fault with the cell. Connect via USB or DC barrel charger and run a full charge cycle through to termination. The low-battery indicator will clear once the cell reaches operational charge, usually confirmed when the charge LED on the calculator extinguishes.