About this replacement
Texas Instruments TI-84 Plus CE — 3.7V Li-ion Replacement Battery (3.7L12005SPA)
This 3.7V, 900mAh lithium-ion cell replaces the original battery in the Texas Instruments TI-84 Plus CE graphing calculator. It also fits select TI-Nspire CX, TI-Nspire CX CAS, and TI-84 CE models. The cell matches the OEM dimensions (52.70 × 42.88 × 4.80mm) and connector spec of part numbers 3.7L12005SPA and P11P35-11-N01.
- TI-84 Plus CE and TI-Nspire CX platform fit: These models share the same 3.7V single-cell Li-ion architecture, identical connector pinout, and BMS handshake protocol — which is why one cell covers the entire platform family.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a TI-84 Plus CE unit. The BMS accepted the cell without fault flags, and the charge controller brought it to 4.2V within the normal charge window.
- RAM backup before swap: Export or photograph all stored programs and variables before removing the original battery. The TI-84 Plus CE stores user programs and variables in RAM powered directly by the main cell — pulling the battery erases everything in RAM with no recovery path.
Calculator clock resetting after battery replacement
The TI-84 Plus CE uses an internal real-time clock (RTC) that draws power from the main battery. There is no dedicated backup cell for the RTC on this platform. Once the main cell is removed, the clock loses its reference and resets to default on reboot. After fitting the new cell, navigate to Mode → Clock and re-enter the correct date and time manually.
Display showing low battery warning immediately after fitting a new cell
Replacement cells ship in storage-discharge state, typically sitting between 3.6V and 3.7V — right at the threshold where the TI-84 Plus CE triggers a low-battery warning. The calculator's firmware reads cell voltage directly and flags anything below approximately 3.75V on startup. Connect the calculator to a USB charger and let it complete one full charge cycle to 4.2V before drawing conclusions about cell health. The warning will clear once voltage climbs above the firmware threshold.