Redesigned RBRfermata

Underwater Battery Canisters

RBRfermata & RBRfermette³

The RBRfermata battery canister extends deployments of all instruments. It automatically configures the internal arrangement of batteries regardless of cell voltage (lithium at 3.6V, alkaline at 1.5V, Ni-MH at 1.2V) to provide a nominal 12V output. Housing 48 individual D-cells and hosting three MCBH connectors, the RBRfermata has both a 12V and 24V option.

The RBRfermata extends deployments by providing up to 2.8kWh of energy to any underwater instrument, which is about forty times greater than our standard battery carriage capacity. An innovative battery carousel coupled with quick-release handles facilitates simple, tool-free battery replacement. A variant with low-profile handles is available for flexible integration with the Wirewalker (DMO). Polyfuses ensure overcurrent protection, resetting automatically after a fault.

As an alternative, you can also extend your deployments using the compact RBRfermette³. Featuring a single MCBH connector, this battery canister accommodates 8 AA cells.

Download Datasheet


  • Up to 2.8kWh capacity for extended deployments
  • Overcurrent protection with automatic reset
  • Pressure relief valve in bottom end cap
  • Three MCBH connectors for power distribution
  • Quick-release handles for tool-free battery replacement
  • Battery carousel holds individual D cells securely
  • 12V and 24V options available
  • Low-profile handles available for more flexible integration
  • Retrofit service available for RBRfermata canisters with shrink-wrapped battery packs


  • 8 AA cell capacity (24Wh - 60Wh nominal)
  • Single MCBH connector for distribution

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