Bird Signal Hawk SH-36s 11.1V Replacement Battery 10400mAh

Bird Signal Hawk SH-36s — 11.1V Li-ion Replacement Battery (3S4P/LIC18650-22C PCM)

This is an 11.1V, 10400mAh (115.44Wh) lithium-ion battery pack for the Bird Signal Hawk SH-36s RF signal strength meter. It fits the SH-36s handheld survey instrument used for cellular network site surveys, field strength measurements, and coverage mapping. The pack uses a 3S4P cell configuration with an integrated PCM for cell-level protection.

• SH-36s platform fit: The Signal Hawk SH-36s runs its RF front end, display, and GPS logging from a single 11.1V rail. This pack matches that rail exactly and carries the same PCM handshake the instrument expects at power-up. Swapping to a pack with a different protection circuit triggers a hardware fault on the SH-36s before the first measurement screen loads.
• Bench tested on actual hardware: We cycled this pack through power-on initialisation and sustained RF scanning loads. The PCM held the 11.1V rail stable through the probe and GPS module wake-up sequence — the current spike that typically trips lower-rated packs did not interrupt the measurement session.
• Pre-deployment calibration cycle: After installing this pack, run a full calibration cycle through the SH-36s instrument menu before heading into the field. The instrument maps battery state during calibration. Skip this step and the SH-36s will throw premature low-battery warnings during your first measurement session, even with a full pack.

BMS cutoff when the SH-36s GPS and RF modules initialise simultaneously

The SH-36s powers its GPS receiver and RF front end at the same moment during cold boot. That combined inrush can pull 2–3A for 200–400ms — enough to trip the overcurrent threshold on a degraded or undersized pack. The result looks like a spontaneous shutdown, not a fault code, so it's easy to misread as a display issue. This pack's PCM is rated for the inrush spike, so the boot sequence completes without interruption.

SH-36s not recognising a new pack after it sat unused in a carry case

Li-ion cells self-discharge during storage, and if the pack voltage drops below roughly 9V the PCM enters sleep mode and blocks all charge input as a safety measure. The SH-36s will power on briefly from residual charge but immediately shut down or refuse to charge. To recover, connect the pack to a charger that applies a trickle or recovery charge at low current — most smart chargers have this mode. Once cell voltage climbs back above 10.5V, the PCM exits sleep and normal charging resumes.