Arri Alexa battery power readout anomalies and voltage optimization with Dionic HC batteries

2011Batteries/Power forum

15 years old. Gear and prices may have changed since.

Battery capacity readouts on the Alexa display showing '1' immediately after power-up reflect estimated remaining runtime in hours at current power draw rather than a malfunction, and actual camera runtime remains acceptable.
The Alexa internally operates as a 24V system and includes a DC-DC converter that upconverts 12V input to 24V for RS port operation.
Powering the camera at 24-28V is more efficient than 12V because it eliminates the need for internal voltage conversion, resulting in lower amperage draw from batteries and extended battery life.
The Alexa automatically selects the power source with the highest voltage when multiple batteries are connected, switching automatically when voltage drops, allowing flexible dual-battery configurations.
Single Dionic HC batteries provide adequate runtime for camera-only operation but produce modest endurance when powering multiple accessories like external recorders, wireless systems, and follow focus units.
Using dual Dionic HC batteries simultaneously via an A/B hot-swap adapter on the camera back improves runtime significantly.
Some operators report better single-battery performance using Hytron 140 batteries instead of Dionic models for handheld work.
The camera accepts input voltage ranging from 10.5V to 34V, with different operational configurations available through menu settings for low power warnings on onboard versus external 2-pin Fischer connectors.

Reports span 2011 timeframe so may not reflect current firmware or hardware revisions.
The preferred '24V' terminology and efficiency gains are described by multiple sources but some details lack official specification documentation in the thread.
Runtime figures are anecdotal and vary significantly based on accessory loads, environmental conditions, and individual camera configurations.
One operator reports the camera did not work with 12V input via the 2-pin power connector, conflicting with general voltage range specifications mentioned.