#1 Back to top 
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An 8 ounce Kraft Parmesan Cheese container happens to
fit into a standard bicycle water bottle cage very well.
Run to your local supermarket (or perhaps your refrigerator) and pick up
a container or two of this cheese.
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#2 Back to top
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Make several Italian dishes over
the next few weeks (or empty contents in to another dish) and then
clean out the cheese container. Remove the label or leave it on
to confuse the competition.
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#3 Back to top
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You'll need a few more items to build this battery pack.
First, pick up two battery holders capable of holding four
C-cell batteries each. Make sure the battery holder arranges the
cells two-by-two as pictured here. There are other battery holders
that arrange all four batteries side-by-side. The side-by-side style will not
fit into the container.
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#4 Back to top
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Purchase two connectors that are compatible with your bike light.
In this case I used Size N Panel Mount Coaxial DC Power Jacks
from Radio Shack. You'll want a connector that you can secure
to a hole drilled into the container. The power jack pictured here
has a nut and flange to make mounting in the hole possible.
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#5 Back to top
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The parmesan cheese container fits snug into a standard water bottle
cage. However, you may wish to modify the container slightly to
overcome any fitting issues unique to your bottle cage. In this case
I need to shape the container to better fit the end of the bottle cage.
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#6 Back to top
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One suggestion to customize the container is to use a heat gun.
The heat will soften the plastic so that you can mold it to
fit your bottle cage. Be careful not to overdo the heat as the
container may shrink or catch on fire. Burning plastic is not a welcome
step in this project.
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#7 Back to top
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Solder lead wires to the connectors.
I recommend installing braided 18 AWG wire as opposed to 20 or 22.
The 18 AWG will reduce resistance from the batteries to your light and
result in better light output. Use heat shrink tubing to prevent
short-circuits.
Drill two holes in the bottom of the container. The size of the holes
depend on the connectors you are using. Feed the leads wires and connectors into
the container and secure with a nut from the inside. Long needle-nose
pliers may come in handy when tightening the nut.
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#8 Back to top
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You'll find that the plastic in the bottom of the cheese container
is thicker and more rigid than the sides. This is
a nice feature as it makes connecting the battery to the light much easier.
Pushing on the connector won't bend the plastic as much as it would if
it were mounted on the side.
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#9 Back to top
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The battery holder will likely come with red and black leads.
Remove these and solder
the connector leads from step #7 directly to the battery terminals.
Consider beefing up the stock terminals by soldering in some pieces
of sheet copper.
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#10 Back to top
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Of course make sure you leave enough length in your wire to remove
and install the batteries. In this example I am wiring two separate
four-cell battery packs. Each battery pack will have a separate
connector. This will allow me to run two lights from two separate battery packs,
or I can run a single light and have one battery pack as a back-up.
Having a back-up battery and light is important when you are out in
the woods at night. All of the 24-hour races I've competed in require
that riders have two completely independent lights.
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#11 Back to top
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Now you're ready to go. The battery pack is complete and
ready to accept batteries.
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#12 Back to top
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I picked up Radio Shack rechargeable NiMh "C" cells
for this bike light. Each cell is rated for 1.2V and 3000mAh.
This is a good capacity for bike lights. Four of these cells connected in series
gives you 4.8V and 3000mAh. With all eight cells
installed, the battery pack has 6000mAh capacity - good for hours and hours of
night riding. You can buy higher capacity cells for less money.
See the recommendations section for more info.
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#13 Back to top
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The assembled battery holders slide into the container back-to-back.
You may have to insert one pack at a time to get them both inside.
Small variations in the battery holder dimensions and cell diameter
make each build unique. You may also need to twist the battery packs
to coil the leads wires for a better fit.
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#14 Back to top
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It is a tight fit, but that is the idea. This battery pack puts
eight C cells into a container that is about the size of a small water bottle.
Plus, the batteries are serviceable. Not many commercial bike light
batteries are serviceable.
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#15 Back to top
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Install the lid. The lid on these cheese container flips open so that
you can shake the cheese out. I thought of using that feature to run the
wires out, but the battery pack wouldn't be as splash resistant or dust proof.
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#16 Back to top
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Snap the lid down and you're ready to ride!
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#17 Back to top
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The battery pack mounts with the lid facing down.
The wire runs up the down tube to the handlebars where your light is mounted.
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#18 Back to top
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Here is a variation on the position of the battery connectors.
In this case I mounted them on the side of the container. Depending
on where your lights are connected to your bike or how you want to run
the power wires, you may wish to use this location.
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#19 Back to top
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There is at least
one benefit to this connector position. That is the wire that you solder
to the connector extends across the bottom of the container rather than
straight into the center and interfering with the space for the battery holders.
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#20 Back to top
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Connectors mounted on the side of the container give you a different
position to run the power leads. Your decision.
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Recommendations
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1.) Pick up some high performance rechargeable NiMh cells such as
those at zbattery.com,
batteryspace.com, or perhaps some of
the Google ads on this page.
2.) If your battery packs move around inside the container, wad up some fabric
and stuff it inside. (Makes sure it's dry and stays dry.) This will prevent the
extra movement from damaging the wires.
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Props
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Featured Instructable at Instructables.com, November 24, 2008.
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Prize winner in the Instructables.com "SANYO eneloop Battery Powered Contest," December 2008.
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