Hello again I am slowly posting in everyone of the subjects. For those of you who have not read any of my other questions I am in the planning stages of my first ROV which I hope to have operational by early to mid spring (aka when the ice melts in northern Wisconsin). My latest question is in regards to powering the ROV. I understand the concept of voltage drop over lengths of cable. To that end I am trying to decide between one of two routes. Before I go on I should also probably ask if the lake I am interested in diving in has a max depth of 105 feet how long of a tether should I shoot for? From the research I have done it seems that cable is sold in 100 foot and 500 foot reels. Back to my main question...Do you think I should run 10 gauge cable hooked to a 12volt source or should I run much thinner gauge (16 or 18) to a 24 volt source with the understanding that by the time it gets to the thrusters/camera it will be down to around 12 volts??
parktrot wrote:Do you think I should run 10 gauge cable hooked to a 12volt source or should I run much thinner gauge (16 or 18) to a 24 volt source with the understanding that by the time it gets to the thrusters/camera it will be down to around 12 volts??
I went with the thinner cable. 100 feet of Cat5e and 22 gauge speaker wire and two 12 volt batteries in series for 24 volts. I haven't priced 10 gauge wire, but the price difference might pay for the extra battery plus the Cat5e and 22 gauge wire is much more flexible.
FYI - The 22 gauge wire - both conductors - was used for a common ground of 8 devices. The Cat5e the positive connection.
Its not really about the voltage along the tether, but the current. The larger the current load, the larger the gauge of the wire must be. These approximations are usually based upon temperature increase in open air, so small gauges can be used underwater. I would not want to rely on the voltage drop along the tether by using a higher voltage source. Also 100 feet of 10 gauge wire with a reasonably high strand count (for flexibility) is not going to be cheap, unless you find a deal on ebay or something like that.
I know this is an old post, but I thought I would place my 2 cents anyway.
Do not rely on the tether length for the voltage drop. You should add a voltage regulator circuit at the ROV to make the voltage stabile. This way as the resistance and other variables change in the tether, you have a nice clean, steady voltage where you need it.
For those of you who have not read any of my other questions I am in the planning stages of my first ROV which I hope to have operational by early to mid spring (aka when the ice melts in northern Wisconsin). My latest question is in regards to powering the ROV. I understand the concept of voltage drop over lengths of cable. To that end I am trying to decide between one of two routes. Before I go on I should also probably ask if the lake I am interested in diving in has a max depth of 105 feet how long of a tether should I shoot for? From the research I have done it seems that cable is sold in 100 foot and 500 foot reels. Back to my main question...Do you think I should run 10 gauge cable hooked to a 12volt source or should I run much thinner gauge (16 or 18) to a 24 volt source with the understanding that by the time it gets to the thrusters/camera it will be down to around 12 volts??
