The purpose is to create a CR2032 battery holder water/dirt resistant with a power switch, using low cost or recycled material.
In this way the battery can be easily installed near the hub of a bicycle wheel to feed LED lights fixed on spokes or on a crash helmet (I will illustrate these applications in other Instructables).
I used a very common plastic (PE) cap of a water bottle that has an inner room that fits the dimensions of a CR2016 or CR2025 up to a CR2032, and the back of another cap to seal the battery inside, welding the PE parts with the tip of a soldering iron.
The switch was pinned on the side of the main cap and electrical contacts to the battery were made with jagged washers and some pieces of a PC flat cable for the wiring.
The outer rim that results can be used to obtain at will buttonholes/holes to install the kit on the final destination using plastic tie wraps or screws.
In this way the battery can be easily installed near the hub of a bicycle wheel to feed LED lights fixed on spokes or on a crash helmet (I will illustrate these applications in other Instructables).
I used a very common plastic (PE) cap of a water bottle that has an inner room that fits the dimensions of a CR2016 or CR2025 up to a CR2032, and the back of another cap to seal the battery inside, welding the PE parts with the tip of a soldering iron.
The switch was pinned on the side of the main cap and electrical contacts to the battery were made with jagged washers and some pieces of a PC flat cable for the wiring.
The outer rim that results can be used to obtain at will buttonholes/holes to install the kit on the final destination using plastic tie wraps or screws.
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Signing UpStep 1: Some of the things used
The material used are a micro switch, a CR2032 Battery and two water bottle PE caps.
It is better to use caps for still water because they don't have reinforcement ribs on the inside or bulges as the ones for sparkling beverages have. This reinforcement is not needed here because of the small weight of the battery (about 4 grams) and mainly not to waste room inside the housing.
You can chose the colour of the caps following your personal taste, but since you will have to connect pieces together, it is advisable to make a welding test to see if the colour charge doesn't give problems.
For my personal choice and to avoid any issue I used white-transparent caps as shown in the picture.
It is better to use caps for still water because they don't have reinforcement ribs on the inside or bulges as the ones for sparkling beverages have. This reinforcement is not needed here because of the small weight of the battery (about 4 grams) and mainly not to waste room inside the housing.
You can chose the colour of the caps following your personal taste, but since you will have to connect pieces together, it is advisable to make a welding test to see if the colour charge doesn't give problems.
For my personal choice and to avoid any issue I used white-transparent caps as shown in the picture.
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Neat idea - The natural springiness of the crinkle washers and the small amount of flex in the caps keeps the connections tight. I could well be using this idea.
Just for info, a CR2032 battery has a capacity of around 200 - 220 mAh so you can work out your expected runtime from that. (e.g. 10 hours @ 20mA, 20 hours @ 10mA etc.)
Before of this solution I just wrapped the battery and the connections with tape and then attached it to the spikes of the wheels using duct tape. Not a robust solution because many times I had to squeeze the battery with my fingers to make the connections work again and sometime with poor results.
I also tried commercial battery holders but after wrapping them with tape to protect from water the result was too thick and cumbersome for my bicycle. Also I still had the problem where to install the switch.
Then I came up with this solution that matches better my requirements.
Yes, I knew about the capacity of the CR2032 batteries, I am happy with it since I am using them on my bicycle wheels to power LEDs since 7 years ago.
I use the bicycle mainly with daylight and I switch the LEDs on only near sunset just to come home safely. So even if the calculated duration might seem short, however it may last many weeks or months and the replacement of the battery may become secondary to the sealing.
I am glad that you are going to use this idea, a friend of mine used it to put a LED light on the collar of his dogs because he likes to play with them in the fields when dark but he needs some help to see them where they run! :-)
If you don't require a perfect sealing but only to keep the battery in place you can instead spot weld the cover to make replacement easier.
If the PE parts got damaged you can do new ones easily re-use all the other parts.
Actually it is a long time that I use CR2032 batteries to power LED lights (2 on each wheel of my bicycle) and they last so many hours that their replacement wasn't an issue compared to their sealing.