About this replacement
Sauter FH 500 — 8.4V Ni-MH Replacement Battery (43.889.0485)
This 8.4V 2000mAh Ni-MH pack replaces OEM part 43.889.0485 in the Sauter FH 500 portable hardness tester. It fits the FH 500, FH-500, and FH500 variants used in materials inspection and field quality control work. Voltage and capacity match the original specification exactly — 8.4V, 2000mAh, 16.8Wh.
- FH 500 series compatibility: The FH 500, FH-500, and FH500 all draw from the same battery bay and use the same BMS handshake protocol. The connector pinout and voltage rail are shared across these variants, so one pack covers the full model range without modification.
- Bench tested on actual hardware: We cycled this pack through simulated hardness test loads, including the current spike that occurs when the probe module initialises. The BMS held without tripping across repeated test sequences, and cell voltage recovered cleanly between measurement bursts.
- Post-install calibration on the FH 500: Run a full calibration cycle through the instrument menu before taking it into the field. The FH 500 maps battery state during calibration — skip this step and the low-battery indicator will fire prematurely on your first measurement session, even with a full pack.
BMS lockout after the FH 500 sat unused in a carry case for months
Ni-MH cells self-discharge during storage, and the FH 500's BMS will not attempt to charge a pack it reads below its minimum recovery voltage. If the pack has been sitting unused for several months, the BMS may not recognise it as a chargeable cell at all. Connecting the charger in this state shows no charging activity — the instrument appears unresponsive to the pack. Place the battery on a compatible external Ni-MH charger first to bring cell voltage up to at least 7.2V, then reinsert it and charge normally through the FH 500.
FH 500 shuts off mid-session despite the display showing charge remaining
The FH 500's battery indicator reads voltage at rest, not under load. When the hardness probe draws current during a test, voltage sags briefly — if the cell is aged or partially discharged, that sag can cross the BMS cutoff threshold and shut the unit down, even though the display showed bars a moment earlier. This is a load-voltage issue, not a display fault. A fresh pack will hold voltage above the cutoff threshold under probe load. If shutdown happens on a new pack, check that calibration was completed after installation — the instrument needs that cycle to set its voltage reference correctly.