Building your own cheap and sturdy waterproof memory card/battery container.

A couple of months ago, I bought a waterproof Olympus 770SW camera. It uses the tiny xD memory cards (25 X 20 X 2mm) and the small li42b rechargable batteries (32 X 40 X 6mm). Since I'm an enthousiastic whitewater kayaker, I want to keep some spare batteries and at least one spare memory card in the pocket of my PFD. That means that the container in which they stay has to be waterproof as well as be able to withstand me bumping my chest into a rock or against the upper deck of my kayak on occasion. This requires that the container is sturdy and waterproof, as well as small enough to fit in that pocket on my PFD. That's a challenge!
Computer hardware stores and camera shops sell several conatiners. One option that I found online was the "Gepe card safe extreme". This costs between 15 and 20 euro, and had room for about twice as many cards and batteries as I was thinking about taking. At 99 x 24 x 77mm it was also way too big for my PFD pocket. Another (relatively cheap) splashproof container that I found, could also store several formats of memory card. One xD memory card plus one li42b battery fit nicely side by side inside this container. I quickly tested the container and found it to be everything but splashproof. One splash on the side and the inside was soaked! Picture of this so called "splashproof" box:

So much for commercially available waterproof memory card containers.

Having visited several sports and outdoor stores, I failed to find a small (less than 10cm (4") long and less than 5cm (2") across) and cheap waterproof container. The ones that came the closest were intended for credit cards, but they looked pretty brittle and their waterproofness seemed less than dependable, considering the flimsy clip with which they closed. The shop owner of one of the shops that sold it also recommeded adding an elastic band around the clip, just in case. Considering the price of an Olympus xD card with 2GB of storage as well as the price of an Olympus Li42b battery (together they add up to well over 100 euro, which also makes it more than 100US$ :-) ) I wasn't going to trust on that container to keep several memory cards and a couple of batteries absolutely dry. In those outdoor stores they also sell small bottles with screwable top for storing jam and so on. Unfortunately they were too narrow to get the battery in and too tall to store in my PFD.

The typical diving shop waterproof containers look like something that you keep dangling from your gear, they are big, round yellow two part containers that screw together to form something that looks like it would work well as a buoy! :-) Alas, too big for my taste!

I looked all over the internet for a small container, having already ruled out the little 35mm film containers (despite good experiences with the transparant film containers from Fuji with my old filmcamera) because they tend to pop open when pressure is applied on the side. I looked at lab supplies, hoping for 30 to 50ml containers with screwable top. I looked at small food storage boxes (rubbermaid and tupperware sell small boxes), but the smallest ones were still four or five times the size I needed, and the lids were not as dependable as I wanted them to be.

Next stop was the military hardware stores. At first I was looking for waterproof matchboxes, but they turned out to be too narrow. Then I looked at the Zippo brand containers used to carry a Zippo lightr on an airplane. Too big and too expensive!

By now I was getting pretty desperate. I asked around on a couple of kayaking forums, but most people there suggested waterproof bags. The last thing I wanted was something that wouldn't protect the contents against impact. On top of that the waterproof bags are just too big to fit in my pocket. I visited geo-cache sites to see what they use as a waterproof container for their hobby. Many things were suggested, but none in the size I wanted.

Next stop was a pharmacy. I asked for the small waterproof pill boxes, they were too small for the batteries. Then they looked into waterproof medicine bottles. None was wide enough, or they were too long. Screw top bottles for cremes were not available... :-( So I walked into a make up store, being intent on getting a wide but flat container with whatever creme or powder they sold, as long as it had a screw top (like the plastic nivea containers). The pretty girl behind the counter was enthousiastic when she heard my demands, and then started unwrapping all kinds of boxes to check for the size of containers. The other female customers soon joined in the search, started pointing and commenting on what might work and what definitely wasn't waterproof. After about 15 minutes and many open boxes, I was none the wiser.

I still had planned a visit to the hardware store, where I accidentally walked through the pipe and tube department. Suddenly I saw what might work. A small piece of threaded PVC pipe, complete with screw on top. The accompanying cap lay in the next compartment. Another customer gave me a weird look when I opened my camera and used the battery to check for the size. There were several sizes of pipe, but I found the 40mm pipe (35mm inside diameter) to be what I was looking for.

Click on the thumbnail pictures for larger resolution pictures.

Wilko
The parts. The assembled container is at the top of the picture. I used Aquaseal to glue the bottom cap to the threaded pipe part. Aquaseal stays flexible for many years, unlike the normal PVC glue which is strong but relatively brittle. The two parts on the left are sold as one here, complete with rubber washer ring. I paid almost 4 euro for one set of three parts.

The size of the container (with opened screw top) compared to the size of the li-42b batteries and xD card. I cut the corner of a six xD card holder (the blue transparant thing second picture from the bottom) which I covered with tape, so that the sensitive parts of the xD card won't touch anything, even if the whole thing is rattled in the waterproof container.

Three li-42b batteries and one xD card fit nicely, with room for another xD card, if necessary.

I drilled small holes through the edge of the screw on cap, so that I can attach it to the bottom part of the container. That way I won't accidentally drop one part in the water, and there's a loop to attach the container to my PFD.

Next I added a couple of layers of bright yellow car paint. I'm curious to see how well it will hold, considering that the outside of the containers is smooth plastic. Maybe I'll have to sand them and redo them sometime in the future.

The containers, as I'm about to fasten the red tie-wraps that connect the top to the bottom part of the container.

Another shot. In the background the minicell pads that I'll glue in the top and bottom of the containers.

A shot with the sizes in cm's and inches and compared to a normal 35mm film container. The waterproof container is based on 40mm pipe parts, which roughly corresponds to U.S. 1, 1/2" parts. The size of the container is about 2 1/4" tall with a 2 1/4" diameter at the top, and 1 3/4" diameter at the bottom.

Another shot with the sizes in cm's and inches and compared to a normal 35mm film container.

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Copyright 2007 by Wilko van den Bergh

Note: All of these pictures are copyrighted by me.
So please don't use them without permission.