## Hardware Design

#### Electrical

##### Power for thrusters
To drive the Minnkota Turbo Pro 324 thruster motors the power system will need to be able to provide 24VDC (from batteries presumably) to maximum current of 30A.  If necessary we can limit the maximum current to 20A. We have designed of a custom H-bridge power amplifier.

The theoretical maximum current, 30A, with 5 thrusters the propulsion system could draw 150A or, power at 24V of 3600W. However, driving all five thrusters at full power is impossible since the maximum vertical travel on the submersible is about 30m and the sub would reach this limit in a minute or less.

In practice once the thurster is in motion, the peak current is 20A. A maximum dive would consume 2 * 24V * 20A = 960W. And a dive with full forward thrust would require 4 * 24V * 20A = 1920W. This is probably the maximum.

A more reasonable estimate may be that forward thrusting pairs (surge) would average full thrust 25% of the time, and the roll pair and pitch pair (or heave) would average full thrust 5% of the time. Thus (0.25 * 2 + 0.05 * 2 + 0.05 * 2) * 24V * 15A = 252W

##### Power for computing and sensing
Rough power estimates for computing:=40W, cameras: 20W, and lights:2*30W=60W, for a total of 120W.

Refer to the power budget for greater detail.

##### Power storage
Total nominal power for the submersible is estimated at 252W for thrust plus 120W-60W=60W for computing and sensing (less lights) for a total of 312W.

Total maximum power for the submersible is estimated at 1920W for maximum thrust plus 120W for other components including lights for 2040W total.

The lower enclosure is 264mm diameter by 605mm length. Typical dimensions for sealed lead acid batteries are 73x175x180mm. As many as 6 such batteries (i.e. Hawker Genesis) would fit in the enclosure, each providing 16Ahrs (at a 10hr discharge rate). Derating the batteries by 30% (to be determined experimentally but approximate fpr a 2hr discharge) for faster discharge and pairing them to achieve 24 volts, gives 3*(0.70*16Ahrs)*24V = 806Whrs

The nominal operating per charge is then 806Whrs/312W=2.6hrs (and at maximum thrust, less than 30 minutes.)

#### Computing

Computing system design [PDF], requirements, comparison of potential components, and final configuration.