Homebuilt Rov Forum

Hey Guys,

I'm new to the forum and also to anything hardware related. I'm a programmer by day but I'm just starting to dable in electronics.

Would something like this 16awg wire work for sending 12V down 100ft to 3 thrusters and a camera?

Using a 12V battery on the surface and assuming a 10 Amp draw you will have 8 volts line loss on 16 guage over a 100ft run. That means at the ROV you have only 4 volts.

Using 24V battery at the surface and the same 10 Amp current draw but this time over 150 feet of 16 guage cable you will wind up woth 12V at the ROV.

He's a few quick tests I have done using different gauges of wire (including speaker wire) so you can maybe get a comparison.

http://www.homebuiltrovs.com/howtotethe ... edrop.html

One other thing I'd like to note if your going through eBay make sure you check the seller feedback first I have gotten screwed in the past buying speaker wire from sellers, they claim it's 16 gauge and it ends up being a thinner 20 gauge.

-Steve

I am currently using 12/2 stranded wire for a 100' tether with 3 thrusters and 60 watts of lighting. This gives me just a little bit of headroom. But at 53 cents per foot it gets expensive in comparrison to 14 or 16 gage. However running out of power at 100' is not what you want to have happen to your ROV.

I use speaker wire for my tether, but I used 3 pairs, one for each thruster. you can buy it by the foot at home depot, lowes etc. or online at monoprice or parts express.

I like the clear insulation stuff because you can easily see it water has gotten into the insulation and is corroding the wires.

We have been doing some testing with running 24 volts down the tether and converting it to 12 volt DC at the ROV.

I just installed this unit on the ROV and have been running the ROV in a pool, and will perform some open water tests soon. The best part of the DC to DC converter is 5 amps down the tether will get you 10 amps at the ROV motors, so the line loss in your tether is reduced by the lower current draw. The 12 volt DC voltage drop down stream of the DC to DC convertor is very small as the wires between the converter and the motors is typically less then a couple of feet.

See this post for additional information http://www.homebuiltrovs.com/rovforum/viewtopic.php?f=15&t=774

The other thing I wanted to mention is stranded wire comes in two types.... thicker strands and fine strands. The thicker standed 14 gauge wire is typically used in AC conduit applications. The finer stranded wire is used in the automotive industry. The fine strand is more flexible.

If you have one, stop by your local surplus store, as they tend to have wire on bulk rolls at a great price. I typically pay .05 for 16 gauge and .06 for 14 gauge wire.

OK where did you find this???

-Steve

I bought mine off of E-Bay

Enter this text in the eBay search field............ "24V to 12V DC to DC Car Power Supply 30a"

Or enter the same search info in Google, and click on images

Here is a typical listing in eBay

Buy it now $9.99 - free shipping
http://www.ebay.com/itm/DC-DC-Converter-Regulator-Reducer-24V-Down-to-12V-30A-MAX-NEW-/120816844442?pt=LH_DefaultDomain_0&hash=item1c213ebe9a#ht_2021wt_952


Jim

What's the heat like on this thing? Would it melt through if I sealed it with wax?

I am not sure the actual temp, but from our tests it wasn't that warm unless you were really pulling a lot of power from it. At that point, I would say it was warm enough to melt/soften wax.

Can you enclose it in a short 3" PVC tube with a threaded end cap, and pot the wires? That is what we do. It is a lot easier with out the wax. Or even a water pfoof pelican case.