RBRfermata and RBRfermette³: underwater battery canisters

RBRfermata and RBRfermette underwater battery canisters

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 the nominal output. Housing 48 individual D-cells and hosting three MCBH connectors, the RBRfermata has both a 14V and 28V 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.

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  • 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 for secure mounting of individual D cells


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

  • 14V or 28V variants
  • Quick-release or low-profile handles
  • 750m, 4000m, or 10000m depth rating
  • Retrofitting options*

*Legacy RBRfermata battery canisters designed for shrink-wrapped battery packs can be retrofitted with the new battery carrousel, quick-release handles, and new electronic hardware. Contact RBR for details.

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