About this replacement
ALPSAT Satfinder Spare Part 3HD — 7.4V Li-ion Replacement Battery (4SF3HDS1)
This 7.4V, 2600mAh Li-ion battery fits the ALPSAT Satfinder Spare Part 3HD satellite signal strength meter. It is a direct replacement for OEM part numbers 4SF3HDS1 and SF3HD-BA. Field technicians use this meter to test satellite reception during installation and troubleshooting, so a functioning battery is critical to getting accurate readings on site.
- Satfinder 3HD platform fit: The Satfinder 3HD runs its signal processing, display, and RF front-end from a shared 7.4V rail. The OEM connector pinout and BMS communication protocol on this replacement match that rail exactly, so the meter's charge indicator and protection logic behave the same as with the original pack.
- Bench tested on actual hardware: We cycled this pack through the Satfinder 3HD's power-on sequence, signal scan, and sustained logging load. The BMS held the output rail steady under the combined draw of the RF module and display backlight without tripping cutoff.
- First-use calibration on the Satfinder 3HD: After fitting this battery, run a full calibration cycle through the instrument menu before heading to site. The Satfinder 3HD maps cell state during calibration, and skipping this step causes the low-battery warning to fire early on your first measurement session.
Why the Satfinder 3HD cuts out when the RF scan initialises
When the Satfinder 3HD starts an RF scan, the front-end draws a short current spike as it powers the LNB port and locks onto the signal. If the battery's internal resistance has risen — through age or deep discharge — that spike causes a momentary voltage dip below the BMS cutoff threshold. The meter shuts off even though the displayed charge level looked fine. A new pack with lower internal resistance absorbs that spike without triggering the protection circuit.
Pack will not charge after the meter sat unused in a carry case for months
Li-ion cells that sit below approximately 2.5V per cell enter a deep-discharge state the BMS cannot recover from through normal charging. The Satfinder 3HD's charger circuit will not begin a charge cycle if the BMS reports a cell below its recovery threshold. If your meter shows no charging activity after connecting power, the pack has likely crossed that threshold and needs replacing rather than recharging. Fitting a fresh pack and running the calibration cycle through the instrument menu restores normal operation.