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Step 5Glue Batteries to Eliminate The Battery Holder or Make a Magnetic Battery Holder
The problem with using small button cell batteries to create a small circuit, is that the battery holder often has as big a volume as the battery itself. If you are trying to make very small battery powered circuits, you can glue the batteries together to create a power pack. This can be useful when making circuits that do not have much room for a holder.
For example, when I was building a one cubic inch robot (pic13B), using a standard size 18x Picaxe, space was at a premium. Even with a custom made battery holder, the contacts took up 2/7 of the usable volume of the batteries and holder.
The 2032 3 volt button cells and many other batteries are steel or stainless steel which is a difficult metal to glue to. The DAP glue #4 seemed to glue the best but had a rather high resistance (about 3 ohms between batteries and wires). So I added some chopped up conductive thread to the mix and reduced it to 1.3 ohms.
This is trickier than it looks. It is very easy to short out the batteries especially when you are gluing between two button cells. Practice with some dead batteries to find out just the right amount of glue to put between the cells without shorting them out.
I had planned to add a 6 volt battery pack to the roll up circuit, but I ran out of time.
Battery Glue Mix #8: 1/4 teaspoon graphite to 1/4 teaspoon DAP Contact Cement to 6-12 inches of chopped up conductive thread. I unraveled the conductive thread which is composed of about 100 fibers as I cut it into 1/8 to 1/4 inch lengths.
Make a Magnetic Battery Holder with Power Switch
When the volume of the battery holder is not critical, magnets work well to create a holder even on a fabric circuit. The batteries, contacts and fabric are held between two strong magnets. In Pic13C you can see how insulating liquid tape was used to create a docking position for the smaller wiper magnet. It is simply slid onto the battery to turn on the power. The wiper was wrapped and twisted with 22 gauge stranded wire and then glued on the top side to keep it in place. For very flexible stranded wire I like to use servo wire.
For example, when I was building a one cubic inch robot (pic13B), using a standard size 18x Picaxe, space was at a premium. Even with a custom made battery holder, the contacts took up 2/7 of the usable volume of the batteries and holder.
The 2032 3 volt button cells and many other batteries are steel or stainless steel which is a difficult metal to glue to. The DAP glue #4 seemed to glue the best but had a rather high resistance (about 3 ohms between batteries and wires). So I added some chopped up conductive thread to the mix and reduced it to 1.3 ohms.
This is trickier than it looks. It is very easy to short out the batteries especially when you are gluing between two button cells. Practice with some dead batteries to find out just the right amount of glue to put between the cells without shorting them out.
I had planned to add a 6 volt battery pack to the roll up circuit, but I ran out of time.
Battery Glue Mix #8: 1/4 teaspoon graphite to 1/4 teaspoon DAP Contact Cement to 6-12 inches of chopped up conductive thread. I unraveled the conductive thread which is composed of about 100 fibers as I cut it into 1/8 to 1/4 inch lengths.
Make a Magnetic Battery Holder with Power Switch
When the volume of the battery holder is not critical, magnets work well to create a holder even on a fabric circuit. The batteries, contacts and fabric are held between two strong magnets. In Pic13C you can see how insulating liquid tape was used to create a docking position for the smaller wiper magnet. It is simply slid onto the battery to turn on the power. The wiper was wrapped and twisted with 22 gauge stranded wire and then glued on the top side to keep it in place. For very flexible stranded wire I like to use servo wire.
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