To power a DIY LED lab project for a group of inexperienced students, I was looking for an inexpensive, clean, and visually attractive solution to attach a Coin / Button battery to a LED circuit.
After trial and error, I found the following method of heat shrinking wire leads onto the Coin / Button battery terminals to be relatively easy and low cost along with conserving space, providing battery short protection, and was visually attractive.
For lack of a better name, I refer to it as a “Heat Shrink Coin & Button Battery Holder”.
In short... Do your own engineering work and analysis of the approach for your specific implementation to determine validity, safety, and assume accountability for the outcome of your engineering assessment; assess and mitigate the risks specific to your scenario and skill level. Use good sense on how, where, and if to use this approach; if you are unsure, do not use it... I would have said common sense, but common sense is definitely not common.
Summary of Procedures:
I did attempt other approaches to secure a Coin / Button battery to a LED circuit; however, my results were mixed.
After trial and error, I found the following method of heat shrinking wire leads onto the Coin / Button battery terminals to be relatively easy and low cost along with conserving space, providing battery short protection, and was visually attractive.
For lack of a better name, I refer to it as a “Heat Shrink Coin & Button Battery Holder”.
Disclaimer: This “Instructable” is provided “As Is” without any express or implied warranty of any kind including warranties of merchantability, noninfringement, or fitness for a particular purpose. The Author of this “Instructable” does not warrant or assume responsibility for the accuracy or completeness of any information, text, graphics, links or other items contained within this “Instructable” post. In no event shall the Author of this “Instructable” be liable for any damages whatsoever (including, without limitation, lost profits, business interruption, lost information, or damaged electronic equipment and circuits) or be liable for any personal harm / pleasure / death whatsoever (including intentional or unintentional, without limitation, cuts, scratch, punctures, bruises, inhalation, swallowing, or insertions) arising out of the use of or inability to use this “Instructable”, even if the Author of this “Instructable” has been advised of the possibility of such damages or personal risks.
In short... Do your own engineering work and analysis of the approach for your specific implementation to determine validity, safety, and assume accountability for the outcome of your engineering assessment; assess and mitigate the risks specific to your scenario and skill level. Use good sense on how, where, and if to use this approach; if you are unsure, do not use it... I would have said common sense, but common sense is definitely not common.
- Getting your Materials (Parts & Tools)
- Get Parts: Coin / Button battery (size dependent on your project), 22 Gauge Solid Wire, Heat Shrink Tubing (diameter size dependent on your battery)
- Get Tools: Diagonal Cutters, Wire Strippers or Utility Knife, Needle Nose Pillars, Scissors or Utility Knife, & Heat Gun or Lighter
- Preparing the Wire Leads
- Cut 2 (qty) Wire Leads (22 Gauge) to desired length for your project
- Strip ends to roughly the length of the Coin / Button battery diameter
- Bend the exposed wire ends into a spiraling shape
- Preparing the Heat Shrink Sleeve
- Select Heat Shrink Tubing diameter that securely holds battery
- Cut piece of Heat Shrink Tubing roughly 1.5 times the length of the battery diameter to make a sleeve
- Inserting the Coin / Button battery into Heat Shrink Sleeve
- Stretch internal diameter of Heat Shrink Sleeve if needed
- Place Coin / Button battery into Heat Shrink Sleeve
- Inserting Wire Leads into Heat Shrink Sleeve
- Insert Wire Leads between battery and Heat Shrink Sleeve
- Applying heat to Shrink Sleeve
- Apply heat to shrink the Heat Shrink Sleeve securing the Wire Leads to the Coin / Button battery
I did attempt other approaches to secure a Coin / Button battery to a LED circuit; however, my results were mixed.
- Incorporation of a button battery holder: Due to confined space and the significant cost adder per project kit, I decided that a molded battery holder was not a viable option.
- Variety of taping methods (including some illustrated here on instructables): Taping was not giving me the clean look I desired. Nor was the taping method necessarily easy when attempting to position and secure two loose wire leads to the Coin / Button battery terminals as you wrapped tape around it by yourself.
- Solder directly onto the battery terminals: Soldering to the battery yielded limited success and I was concerned with my student’s ability to utilize this method along with any potential battery damage due to excessive heat. I did evaluate batteries with soldering tabs; however, I found them to be a significant cost adder compared to a regular bulk Coin / Button battery.
- Conductive glue / epoxy: Yielded similar frustrations as taping and came with the additional concerns around the chemical makeup.
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Signing UpStep 1: Material List (Parts and Tools)
Parts
-
Item: Coin / Button Battery
- Use: Intended to power your electronic project. I have used a variety of Coin / Button batteries including CR2032 (3v 20mm × 3.2mm), CR927 (3v 9.5mm × 2.7mm), CR1025 (3v 10mm × 2.5mm), LR44 (1.5v 11.6mm × 5.4mm) with this process. The type of Coin / Button battery really depends on what your power needs are.
- Price: Depends on supplier and volume. If you are buying in large volumes, I recommend hunting around for the best deal.
-
Item: 22-Gauge Solid Hookup Wire
- Use: Used to make battery leads which provide continuity from battery to the desired circuit. I prefer using two colors (Red and Black) to label polarity when attached to the battery; however, use whatever color you want.
- Price: 22-Gauge Solid Hookup Wire is pretty inexpensive. On average it costs less than 1 cent per inch. At your typically electronic store, you can pick a 25’ spool for about $3.00.
-
Item: Polyolefin Heat Shrinkable Tubing
-
Use: Provides a compression / mechanical bond of the two individual 22 Gauge Wire Leads to the Coin / Button battery terminal once shrunk when heat is applied. Each Coin / Button battery usually requires a different Heat Shrinkable Tubing diameter size.
In my trials, I have found that the following batteries work well with the following 1-2 Heat Shrink Tubing diameters and sleeve lengths:- CR2032 (3v 20mm × 3.2mm) – Heat Shrink Diameter: 1/2 inch; Sleeve Length: 1 1/4 inches
- CR927 (3v 9.5mm × 2.7mm) – Heat Shrink Diameter: 1/4 inch; Sleeve Length: Length 5/8 inch
- CR1025 (3v 10mm × 2.5mm) – Heat Shrink Diameter: 1/4 inch; Sleeve Length: Length 5/8 inch
- LR44 (1.5v 11.6mm × 5.4mm) – Heat Shrink Diameter 3/8 inch; Sleeve Length: Length 5/8 inch
- Price: Price really depends on volume and from where you purchase. For example, allelectronics.com has 1/2" X 4' Heat Shrink Tube in black for about $2.50. So if you were using that tubing for the CR2032 batteries, which needs a length of about 1 1/4 inches for the sleeve, you would get about 38 sleeves out of those 4 feet at an average cost of 6 cents a sleeve.
-
Use: Provides a compression / mechanical bond of the two individual 22 Gauge Wire Leads to the Coin / Button battery terminal once shrunk when heat is applied. Each Coin / Button battery usually requires a different Heat Shrinkable Tubing diameter size.
-
Item: Small Zip Tie / Cable Tie (Optional)
- Use: Apply additional compression to the heat shrink sleeve, wire leads, and Coin / Button battery package.
- Price: Price really depends on volume and from where you purchase; however, it is typically an average cost of less than 1 cent a tie.
- Diagonal Cutters: Cutting the 22 Gauge Hookup Wire
- Wire Strippers or Utility Knife: Removing insulation from wires
- Needle Nose Pillars: Makeshift jigs to wrap the bare wire ends around and something to finesse the battery into the Heat Shrink Sleeve (if needed)
- Scissors / Utility Knife: Cutting the Heat Shrink Tubing
- Heat Gun or Lighter: Applying Heat to shrink the Shrink Tubing
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http://www.thinkgeek.com/product/b70c/?pfm=Search&t=conductive%20glue#tabs
Beyond the potential chemical concerns, the decision not to use Wire Glue (Conductive Glue) for this project was also based on various peer reviews that the Wire Glue had limited tackiness / adhesive qualities on initial application, required components to be held in position or clamped for a long time during drying, and needed to be put on fairly thick to be effective causing concerns around visual appearance. On top of that, I did not think my students had the patients or application precision to effectively use it for this project.
The same stuff that is sold on ThinkGeek is also sold on Amazon, which has several reviews on the product (both positive and negative). http://www.amazon.com/Electrically-Conductive-Wire-Glue-Bonds/dp/B000Z9H7ZW/ref=cm_cr_pr_product_top
--Matt Royer
Thanks for sharing!
I do like your solution though. It's very compact and cost-effective for doing little embedded projects. Thanks for posting.
As noted in the instructable, for added security, a small zip / cable tie can be optionally used to apply additional compression to the heat shrink sleeve, wire leads, and Coin / Button battery package if you feel a particular application needs that additional support.
--Matt Royer
Personally I've had great success soldering to all sorts of "difficult" surfaces including the inside of a car window demister and battery ends.
The three things that make it possible are decent liquid flux, pre-soldered wire, and a really hot iron. I use a butane soldering iron which is perfect.
On the other hand I also use and value good heatshrink. But its not cheap, so I've bought some from dx.com which has proved versatile and handy.
Good work.
Nice little project!
Short exposure with the minimum required heat to shrink the Polyolefin tubing followed by a ramped cool down is recommended. A sustained high temperature, above operating max thresholds, can cause self-discharging, battery failure, leakage, or catastrophic failure. So, don’t leave a sustained heat on it.
However, with any engineering activity… I do recommend that you do your own analysis, risks assessment, and draw your own conclusion based on your data.
--Matt Royer
So thank you very much for your idea, another good example of the advantages of KISS (Why solder? Heat shrink is enough!)
Regardless, I still like your idea of using shrink wrap. Well done.
I have some old books & magazines belonging to my dad that for all intents & purposes were the "Instructables" of the time.
The first thing that struck me was the difference in 'instructing' & the projects proposed, you were expected to 'make do', improvise & understand what you were letting yourself in for.
The projects proposed were (by today's standards) 'adventurous' - if you could not obtain a specific item ...use something close - you were given enough info to get going & expected to continue in your own way - once started if things went wrong well ....you should have known better than to start.
In short I could not smile inwardly when reading your instructable & its comprehensive detail - as in the back of my mind I kept on thinking that the 'old instructable' would have began & ended with the original picture ....but in black & white.
I like your final photo, which shows an image of the stripped/coiled wire under the heat shrink.
Bill W