DIY underwater light from a jar

[anchelo12345]

I would like to try and build a diy dive light from an ikea slom jar.
(Sorry can't post the link because i don't have 5 posts - just go to the ikea homepage and put in slom as a search term - i use the 1.8l version)

It is ~5mm(0.19in) thick. How much pressure can i expect it to be able to withstand? I will use a lead acid battery and a energy saver 15W (900lumen~75W incandecent eqivalent)light bulb that runs on 12 Volts DC. I will put both inside the jar and cover the back side with mirror foil.

I have already built it, but i have no way of pressure testing it, because i live in Vienna, Austria and there is no lake in a 100km (60mi) radius that is deeper than 10m(30ft). And i don't want to test it while on diving holiday in Egypt.
Has anyone on this forum used a similar jar as a pressure vessel before?

I have read ab out some people building similar pressure containers from PVC pie which can withstand a pressure of 5bar or 50mt(150ft). How thick is the pipe that you have used? I would be very happy if my jar can take the pressure of 3bar or 30m(90ft) of water.

Thank you for any answers you could give me.
Angel

 

[dave4868]

This is your lucky day, not only because you've found ScubaBoard, but because I happen to have a very similar bottle that I can test for you!

My LDS has a pressure pot that I can use.

I'm going to guess your bottle will do fine well beyond twice your required depth. I tested my DIY PVC camera case with a 6mm plate glass lens and it was fine at 10 atmospheres....

I'll get back to you in a few days.

Welcome to ScubaBoard!

Dave C

 

[anchelo12345]

Thank you very much!
This is really great.
Here is a list of all the components:

conrad-uk.com/goto.php?artikel=250177
for the lead acid battery - cost me 22€

conrad-uk.com/goto.php?artikel=610328
for the light bulb - cost me 16€

Total cost: 43€(including smaller stuff like switch, cables, mirror foil)

I think this is the cheapest 900 lumens UW lamp you can get.

With this 2,3 Ah lead acid battery it last for about 1 hour 40 minutes. If you get the larger jar, you could also use a larger bulb wich uses 22Watt.(Didn't use it because i think, that the larger jar will be more likely to get crushed)

Angel

Thank you again for doing this testing!

 

[anchelo12345]

Here the link for the jar:
ikea.com/us/en/catalog/products/60065866

 

[gcbryan]

Thank you very much!
This is really great.
Here is a list of all the components:

conrad-uk.com/goto.php?artikel=250177
for the lead acid battery - cost me 22€

conrad-uk.com/goto.php?artikel=610328
for the light bulb - cost me 16€

Total cost: 43€(including smaller stuff like switch, cables, mirror foil)

I think this is the cheapest 900 lumens UW lamp you can get.

With this 2,3 Ah lead acid battery it last for about 1 hour 40 minutes. If you get the larger jar, you could also use a larger bulb wich uses 22Watt.(Didn't use it because i think, that the larger jar will be more likely to get crushed)

Angel

Thank you again for doing this testing!

Here's one for 60 euros: DealExtreme: $81.00 Diving Cree SSC-P7-C-SXO 3-Mode 900-Lumen LED Flashlight Kit (2*18650/4*CR123A/4*16340)

When you have enough posts to be able to post a picture of your light please post it. I'd like to see it.

 

[anchelo12345]

Update:
I tested it now in the bathtub and it laste for 1 hour 48 minutes, however the ligh became considerabliy weaker after about 1 hour 20 minutes.

 

[anchelo12345]

@ gcbryan:

I have to say that the light you mention is probably better than the one i am using because it is much more focused. I have an angle of illumnation of almost 180°. It is also much larger. The light is comparable to switching on the light in my room(also hava 15W enregy saver bulb) I can only imagine how great it would be to just switch on the lights in the cargohold of thistelgorm. I will post a picture of the light soon.

 

[dave4868]

I missed the "1.8l" in your orginal post and what I have is actually 0.5l, almost identical to the Ikea SLOM 0.5l.

My bottle has the same sealing mechanism as yours, though, so, just for fun, I went ahead and tested it today in a pressure pot at a gauge pressure of 135psi (about 9 atmospheres): no leaks, no damage.

Since your jar is about 2.5cm wider and more than double the height of the one I tested, the adequacy of your sidewall is still in question.

IMO, your seal will definitely be fine and your sidewall will probably be more than adequate for your intended depth and pressure (30m, 3 bar). But then, it's not my 43 Euros inside....

If I can find a closer match to your bottle, I'll do some more testing....

Dave C