Bosch B169 HFG89 Compatible Battery 7.2V 1200mAh

Bosch HFG89 / HFG169 / HFG450 / FuG11b — 7.2V Ni-MH Replacement Battery (B169)

This is a 7.2V 1200mAh Ni-MH replacement for the Bosch B169 battery pack. It fits the HFG89, HFG169, HFG450, and FuG11b two-way radios. Capacity is drawn from the product specification — 8.64Wh total energy.

• HFG and FuG11b platform fit: These four models share the same 7.2V two-cell Ni-MH voltage rail, identical connector pinout, and matching BMS handshake profile — which is why one pack covers the whole group.
• Bench tested on actual hardware: We cycled this pack through full charge and PTT transmit load on the HFG89 dock. The BMS handled the transmit current spike without tripping, and the charger accepted the pack and moved to the green charge state within the normal window.
• First-insertion contact check on the HFG dock: If the dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The HFG charger platform runs a contact-validation cycle before it accepts the BMS handshake — a single debris layer on the contacts is enough to block it.

Why the HFG89 drops to reduced TX power mid-shift on a new B169 pack

Ni-MH cells leave storage at a suppressed voltage — typically 1.1–1.15V per cell rather than the 1.2V nominal. Under sustained RF output, the radio's power amplifier sees the voltage sag and steps down transmit power to protect the PA stage. This is not a fault in the replacement pack — it is the radio's built-in voltage sag response. One full charge-discharge cycle brings both cells to their rated voltage and the sag narrows significantly. After the first full cycle, sustained TX output should hold at normal power through the shift.

Bar indicator showing one fewer bar than expected after fitting the B169

The HFG series uses a voltage-threshold bar indicator — each bar corresponds to a fixed voltage step, not a percentage reading. A new pack at storage voltage sits just below the top threshold, so the indicator shows one bar short of full immediately after insertion. This clears after the first complete charge cycle drives both cells to 1.4–1.45V per cell at end-of-charge. If the indicator still reads low after a full charge, check that the dock contacts are clean and the charge LED progressed correctly to green before removal.