Outdoor Enclosure Power Switch Ideas

[petersanch]

Hi All
Im making a circuit board to go inside an outdoor enclosure to make the project water tight against rain and humidity. The project is powered by a battery pack inside the box. I would like to be able to switch power without opening the box but I dont want to drill a hole in the box to not break the water tight seal.

I have the idea of using a capacitive button but that has an active circuit and needs to use battery to work . Any ideas for controlling power without opening the box and without drilling a hole?
Cheers!

[nfmax]

If the box is plastic, you could avoid making any holes by using a reed switch inside the box and a magnet outside it. Some sort of a permanent clip for the magnet might be needed, depending on the operating mode you envisage & the duty cycle. If the circuit takes more than the 50mA or so a reed switch will cope with you will need a secondary switch, e.g. a MOSFET as well.

Incidentally, beware of waterproof plastic boxes. In my experience, when exposed to the great outdoors, the combination of sun/UV and temperature cycling will warp the plastic enough to relieve the compression on the gasket seal, which will then leak. I think you need a screw fixing at least every 8cm or so to keep things tight. Or do what I did, get rid of the gasket, and replace it with outdoor flexible 'decorator's caulk' (PVA-based). Silicone works as well, but is very difficult to get past when the time comes to replace the batteries. I speak from experience

[Gyro]

Watertight diecast boxes (the ones with the O ring seal) are better in this respect. They are still non-ferrous so the reed swich trick would still work.

[d-smes]

Water vapor is a funny thing- it WILL get into your waterproof box.  And after a few weeks / months of barometric pressure changes, temperature cycling, and such, you'll find water in the bottom of the box when you go to change batteries.  Best to drill a small weep hole in the bottom or install a "breather".   See https://www.gore.com/resources/faq-for-gore-protective-vents

[Mechatrommer]

Any ideas for controlling power without opening the box and without drilling a hole?

how do you put in electronics stuffs in the first place when the box has no hole or opening? my point is, it got hole it just controlled or sealed with some mechanism, you should do the same with controlling it, drill holes for keypad and then use soft plastic or rubber to seal the hole but at the same time, be able to press from outside. afaik, no factory can produce (consumer grade at least) what exactly you want.

[2N3055]

Water vapor is a funny thing- it WILL get into your waterproof box.  And after a few weeks / months of barometric pressure changes, temperature cycling, and such, you'll find water in the bottom of the box when you go to change batteries.  Best to drill a small weep hole in the bottom or install a "breather".   See https://www.gore.com/resources/faq-for-gore-protective-vents

Listen to this. You have to make vent hole or install breather...

[nfmax]

It is quite possible to hermetically seal an enclosure, even with cable entries, if you do it right. But even so, you will introduce some moisture each time you open it to change the batteries, and as @Mechatrommer says, to do it properly is outside the realm of consumer pricing. One way to control residual moisture is to use silica gel (in generous quantities), replacing it each time you change the batteries. This copes with the initial 'charge' of water vapour as well as subsequent water vapour penetration.

You ought to be able to get a good enough seal that you don't end up with liquid water in the case though, even at consumer prices.

[petersanch]

Thanks for all of the comments! I like the idea of using a reed switch. Does any one know if a store like Digikey sells a  kind of magnet that can be mounted outside the enclosure and can slide or flip to move away or infront of the reed switch? This seems more like a hardware part.