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(Richard) #1

@Rusty- have you guys ever tested something like this? Epoxy the switch in place through the backplate and epoxy in the screw on boot. If you haven’t I’ll give it a test.

http://www.ebay.com/itm/30-Amp-DPDT-3-Position-On-Off-On-Toggle-w-Cover-7075-TSO-Switch-12-Volt-/111809432760?hash=item1a085c8cb8:g:U9UAAOSwd0BVvteZ


(Rusty) #2

Richard,

No we haven’t but that’s definitely an interesting idea. I’d love to hear how that goes.

-Rusty


(Richard) #3

OK, I’ll give it a try.


(Joe) #4

Rusty or anybody else

What are you using for a switch

I have read of some using a reed switch and a magnet from out side the WTC

 

Joe


(Rusty) #5

Joe,

We haven’t used switches underwater. Some of our future stuff will be powered on through the tether.

Using a reed switch with a relay or MOSFET is a good approach and we know a few people using that approach successfully. You can also use a hall-effect sensor, which is another type of magnetic switch.

Sorry I don’t have more suggestions!

-Rusty


(Andrew) #6

Hi,

Haven’t used the, on a ROV, but have successfully used these SSR-40A DD DC/DC 5V 12V 36V Solid State Relay for Temperature Controller Arduino in a home automation project last year.

Advantages are they’re cheap and switch high current DC very well. Downsides are they generate a bit of heat at high current and are a little bulky.


(Richard) #7

I am, in general, distrustful of any high current solid state switching device in an enclosed environment with no air flow over the heat sink. Plus, a large enough heat sink takes up a lot of room, which is at a premium for my design.

@Joe-I just use the battery connectors as my switch. Pain in the butt, but highly reliable.


(Joe) #8

Thanks Guys

On my present ROV I just remove the end cap to turn on and off problem is that by opening it up every time re allow moisture in causing the dome to fog at least in the winter months.

An old Video housing I have uses external knobs with a rod on the inside for a few of the functions.

I will look into the relay or mosfet but as mentioned above the relay anyway would be drawing power and creating heat although I don’t think to much heat

Joe


(Richard) #9

An advantage to the double throw mechanical switch is the ability to switch the batteries between discharge to the esc/motor and charge from an external connector (doesn’t need protection from the seawater).


(TCIII) #10

Hi All,

It should be noted that this double pole switch is rated at only 30 amps.

If you have a 6 Thruster ROV, as I do, then you are limited to only 5 amps per Thruster if they are all on at the same time to stay within the switch’s current carry capacity.

Even if the Vertical Thrusters are in the idling state drawing around 1 - 2 amps, this still means that you are limited to a little over 6 amps per Thrusters which is around 1/2 of their maximum operating current.

And the above does not even take into account a navigation controller, lights, gripper, camera, etc.

So it will probably be necessary to have more than one switch to stay within the switch’s current carrying capacity.

Regards,

TCIII AVD


(Richard) #11

Being a double pole switch I believe it is rated for 30 amps on each side/pole, not total. In my 3 thruster environment I would use 2 switches, having a battery and thruster tied to individual switch poles. In the current size WTE I am using, I don’t have room for any switches. Next build will have to be a longer WTE (my current one is 8"), but I am loathe to do that. Right now, out-of-water weight is 12 pounds, with 2 of that being for negative ballast. It is about as heavy as I want to go. On a rocking small boat, things start getting hard to handle above that weight. One of BR’s 12" WTE tubes will put the weight close to 20 pounds.


(Pierson) #12

My team uses an oil tight washdown switch from mcmaster, and have been very happy with it. switch goes through the bulkhead, and if the current limit is not high enough just use the switch to control some FETs or relays. both are relatively small. you also could have the relays/killswitch system external, between the bulkhead and motors, if internal space is a high premium. but you would need to pot it or make a second enclosure.

http://www.mcmaster.com/#8002k71/=10ojryu