PWM and voltage problem for Homemade submarine control.

[ScubaShane]

I'm currently working on a project and need help figuring out the best arrangement for the electronics. I hate to make long posts, but to understand where I am running into problems I am going to have to list the requirements basically before I ask.

The project is an underwater Remote Vehicle, to be used inspecting large tanks of water.

I have 5 DC motors I need PWM's to operate (2 pairs and 1 solo, all draw 2.5amps max at 12v), 1 small video camera and 2 LED lights (around 10w each).

The Vehicle must have a cord attached (wireless doesn't work well in large bodies of water or inside big steel tanks). Ideally the cord will be 200-300 feet long

The cable needs to be close to neutrally buoyant and not too bulky (was leaning toward Cat5e).

1. So the first question is about powering the vehicle. With a max draw of maybe 15 amps and a 12vDC power supply (180W, hopefully less), what gauge of wire would I need to effectively transmit that through 200-300 ft of wire. If it is too heavy a gauge I will have to invest in on-board batteries.

2. If I can power it from the surface, would it be possible to build the PWM into the surface controls or would it be better to have them inside the hull.

Well I have many others but I will start with those 2. Everything else depends upon these. Thanks for reading!

 

[sabuthankappan]

Use Battery if you cannot allow some 3-4V cable drop. Better to have PWM on vehicle.

 

[nsaspook]

You could use a DC to DC converter to convert a higher supply voltage (30-60vdc) to the 12dc needed for the motor drivers.
Don't try to use a network cable, use something designed for the application like multi conductor marine cable.
**broken link removed**

 

[vimalkhanna]

You shall need to go for 250VDC input to your cable and have 30W SMPS units on board .
Best is to use four mini converters of COSEL DHS50 series which accept 180VDC to 350VDC/0.6Amps and deliver 12VDC /4amps each .
The starting currents of your isolated /indep motors may be high.(three nos)
Beldens Snake cables are high flex multicore types (used in Lifts,cranes and forklift trucks) .
You get static shielded and double sheathed weather and oil proof versions .
Fourth converter powers the LED lamps 20watt and video camera 15watts + ??
Would you just inspect and handle images recd or have jaws to trigger action from the surface ??