About this replacement
Celestron CoursePro / Course Pro Elite — 3.7V Li-Polymer Replacement Battery (HC11C08)
This 3.7V, 1350mAh lithium-polymer cell replaces the original HC11C08 battery in the Celestron CoursePro and Course Pro Elite handheld GPS navigators (models 44870 and 44871). It matches the original cell's voltage, capacity, and physical dimensions — 50.80 × 34.00 × 7.60mm — so it seats correctly without modification. Swap it in when your unit no longer holds a charge through a full navigation session.
- CoursePro and Course Pro Elite compatibility: Both the 44870 and 44871 share the same battery bay dimensions, connector pinout, and 3.7V power rail, so one cell covers both units. The integrated BMS communicates charge state to the firmware the same way across both models.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on the bench, confirmed the BMS reported accurate state-of-charge to the device firmware, and verified the protection circuit tripped correctly at the low-voltage cutoff threshold.
- First-use satellite acquisition: After fitting this cell, power the unit on outdoors before relying on it for navigation. The GPS performs a cold start after any full power interruption, which means first satellite fix can take 5–10 minutes. Subsequent warm starts drop back under a minute once almanac data is cached.
GPS accuracy reduced when the CoursePro battery runs low
At low battery, some GPS units step down receiver sensitivity to extend remaining power. On the CoursePro, this can cause position drift or slower track updates before the unit shuts off. A degraded original battery hits this low-power threshold faster than a fresh cell, so accuracy problems often appear earlier in a session than expected. Fitting a new 1350mAh cell restores the full operating voltage window and keeps the receiver running at full sensitivity throughout use.
CoursePro shuts off without warning before the battery indicator reaches empty
This happens when an aged cell's actual capacity has dropped well below what the firmware expects. The on-screen indicator is calibrated against a full-capacity cell, so when internal resistance rises, voltage collapses suddenly under GPS load — hitting the hardware cutoff while the display still shows one or two bars. A new HC11C08 cell brings internal resistance back in line with the firmware's charge model. After fitting, run the unit through one full charge cycle outdoors so the indicator re-syncs to the cell's actual voltage curve.