Auxiliary electrical power generation for submersible unmanned vehicles using a seawater-activated galvanic cell to extend avionics and sensor endurance.
An auxiliary power subsystem for a transmedium drone comprises an aluminium structural electrode and a consumable sacrificial magnesium electrode separated by a flow-through channel that admits seawater only when the vehicle is submerged. On submersion an immersion-actuated port opens the channel, the seawater acts as electrolyte, and the galvanic couple generates low-power direct current. A conditioning circuit regulates the output and directs it to trickle-charge an avionics and sensor bus and, within a bounded rate, to slowly top up a primary lithium-polymer battery during submerged loiter. The magnesium electrode is consumed during operation, so the cell is a primary auxiliary source bounded to low-power housekeeping loads; it is expressly not a flight power source and cannot sustain rotor or thruster propulsion. The subsystem extends submerged loiter and standby endurance, keeps navigation and sensing alive during quiescent periods, and reduces primary-battery depletion while the vehicle waits, drifts, or performs low-rate sensing. Claims are scoped to auxiliary, avionics, sensor, and loiter-extension functions.
Small submersible drones are battery limited. Lithium-polymer packs that are sized for short aerial flight are quickly depleted when a vehicle must also loiter submerged while sensing or waiting for a tasking, and battery exhaustion during submersion risks loss of the vehicle. Seawater-activated batteries are well known in marine engineering: magnesium and aluminium anodes coupled in seawater electrolyte produce useful current and have been used in marine beacons, sonobuoys, and emergency lights. Sacrificial magnesium and aluminium anodes are also standard for cathodic corrosion protection of hulls. However, these prior uses are stand-alone power cells or corrosion anodes; they are not integrated into a transmedium drone as a submersion-gated auxiliary that uses a structural aluminium member as one electrode and conditions its output specifically to sustain an avionics and sensor bus and to bounded-rate top-up of a primary battery. A naive integration risks two failure modes: over-claiming the cell as a flight power source, which the chemistry cannot support at rotor power levels, and continuous corrosion of the structural electrode even when dry. There remains a need for a submersion-gated galvanic auxiliary that opens only when wet, that is bounded to low-power housekeeping and loiter-extension loads, and that protects the structural electrode when the vehicle is in air.
The invention provides a submersion-gated galvanic auxiliary cell for a transmedium drone. An aluminium structural electrode and a consumable magnesium electrode are arranged across a flow-through channel. An immersion-actuated port keeps the channel closed in air and opens it on submersion so seawater becomes the electrolyte and the couple generates low-power DC. A power-conditioning circuit regulates the output and, under a controller, distributes it to trickle-charge an avionics and sensor bus and, at a bounded charge rate, to top up a primary lithium-polymer battery during loiter. The controller enforces a hard cap so the auxiliary output never supplies propulsion-level current; the cell is a primary anode-consuming auxiliary, not a flight source. A flush or purge feature clears the channel on water exit to limit residual corrosion, and the consumable magnesium electrode is replaceable. The result is extended submerged loiter and standby endurance and reduced primary-battery depletion during quiescent submerged operation, without any claim of sustaining flight.
FIG. 1 is a schematic of the auxiliary power subsystem showing an aluminium structural electrode (30), a consumable magnesium electrode (32), a flow-through channel (34), an immersion-actuated port (36), a power-conditioning circuit (38), an avionics and sensor bus (40), and a primary lithium-polymer battery (42). FIG. 2 is a section view showing the channel (34) between the electrodes with the port (36) closed in air. FIG. 3 is the same section with the port (36) open during submersion and seawater (44) flowing as electrolyte. FIG. 4 is a block diagram of the power-conditioning and distribution circuit with a controller (46) enforcing a current cap. FIG. 5 is a flowchart of the auxiliary power management method. FIG. 6 is a detail of the replaceable magnesium electrode cartridge and a purge feature (48). In air, the immersion-actuated port (36) is closed, so no electrolyte bridges the electrodes (30, 32) and negligible galvanic current flows, protecting the structural electrode from unnecessary consumption. On submersion, an immersion or pressure trigger opens the port (36); seawater (44) enters the channel (34) and forms the electrolyte of a galvanic couple in which the magnesium electrode (32) is the anode and is progressively consumed, while the aluminium structural electrode (30) serves as the cathode and as part of the airframe. The couple develops a low open-circuit voltage and modest current. The power-conditioning circuit (38) regulates this output. Under the controller (46) the conditioned current is directed first to the avionics and sensor bus (40) to sustain navigation, sensing, and communication during submerged loiter, and any surplus is applied to the primary battery (42) at a bounded trickle rate. The controller (46) enforces a hard current cap so that the auxiliary output is restricted to housekeeping and loiter-extension loads and never supplies propulsion-level current; propulsion remains powered solely by the primary battery (42). On water exit the port (36) closes and the purge feature (48) clears residual seawater from the channel (34) to limit further corrosion. The magnesium electrode (32) is provided as a replaceable cartridge (FIG. 6) so the consumed anode can be renewed between missions. In an embodiment a coulomb counter logs anode consumption to estimate remaining auxiliary capacity.
| Patentability | 76.0% |
| Prior-art position | 52.0% |
| Technical merit | 56.0% |
| Commercial | 56.0% |
| Composite genius score | 62.2/100 (Marginal) |