ALEXA 35 powering down when 24 V sled cable is disconnected or sled battery is swapped; voltage priority and status indicators.

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2025From a Facebook group: The Steadicam Group

DisputedParticipants disagreed and reached no conclusion. Read the findings as positions, not as an answer.

When a sled battery is removed, voltage at the camera cable drops from 24 V to 12 V, triggering an internal undervoltage cutoff in the ALEXA 35 that prevents restart from the sled.
Remedy: disconnect the sled power supply or camera cable before swapping the battery; check the two status lights on the right side of the camera body (rear light indicates onboard battery, front light indicates block/sled supply; red = error, green = in use, blue = available but not in use).
Setting onboard battery priority in the camera menu prevents power-down issues during sled battery swaps, as reported by operators using Dragonfly and Betz Tools sleds.
Other possible causes include defective batteries from certain manufacturers (requiring return for repair), Quick-Swap module issues, or miswired camera cables.
Under load (two motors, measurement device, wireless transmitter), the ALEXA 35 operated reliably down to approximately 24.6 V; battery swaps are better performed around 25 V to maintain margin.
One operator supplies the ALEXA 35 exclusively from onboard batteries when using a GPI Pro sled with Cinelive electronics, because it powered down without warning when powered from that sled.

Power priority settings available in camera menu; specific sled model and electronics (Dragonfly, Betz Tools, GPI Pro, Cinelive); battery manufacturer and condition; accessory load (motors, wireless, metering).