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This page describes the construction of a universal bike light battery with eight "C" cell rechargeable NiMh batteries. It is made from a Parmesan cheese container which is strong, lightweight, splash proof, dust proof, fits in a water bottle cage, and allows for complete serviceability of the batteries.
High performance NiMh cells can raise the capacity of this unit to as much as 10,000 mAh.

This project was originally featured here: http://www.racedaynutrition.com/features/battery.aspx.

A complete shopping list can be found here: http://www.racedaynutrition.com/features/battery.aspx#shoppinglist

Step 1: Make Several Italian Dishes

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.
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.

Step 2: 4-cell Battery Holders

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.

Step 3: Power Jack

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.

Step 4: Good Fit

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.

Step 5: Better Fit

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 Instructable.

Step 6: Drill Two Holes

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.

Step 7: Strong Plastic

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.

Step 8: Beef Up the Terminals

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.

Step 9: Leave Yourself Some Room

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.

Step 10: Ready to Go

Now you're ready to go. The battery pack is complete and ready to accept your choice of "C" cell batteries.

Step 11: Choose Your Batteries

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. Higher capacity cells are available for less money . Since the batteries represent the majority of the cost and control nearly all of the performance of this Instructable, do some comparison shopping before settling on a model.

Step 12: Slide, Twist, & Turn

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.

Step 13: Tight Fit

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.

Step 14: Close the Lid

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.

Step 15: Ready to Ride!

Snap the lid down and you're ready to ride!

Step 16: On the Bike

The battery pack mounts with the lid facing down. The wire runs up the down tube to the handlebars where your light is mounted.

Step 17: Variation

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.

Step 18: Better Wire Position

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.

Step 19: Side Mount

Connectors mounted on the side of the container give you a different position to run the power leads. Your decision.
holy... 10,000 mAh??? that's like, woah...
It's like 10 amps. Yea, I know, you could run a 55w halogen headlight off of that.
<p>The brighter the bulb, the faster the battery will die</p>
Why not just use a wide mouthed screw top water bottle, that is made for the bottle holder and will handle abuse a lote better than these food containers. They are usually made of thick type 1 plastic (recycling code on bottom of bottles). Then you will have a nice tough lid too. Also when it rains it can really rain. Plug in battery terminals on top would be simply hopeless, put them on the bottom and that way water will run off. Or far better is use a pair (red and black)Anderson connectors on leads to batteries that will make sure the battery is polarised correctly and you don't fly anything you connect to the battery! If you happen to have a dynamo on the bike and just use a spare light for night riding then instead of NiMH use a small gell cell/slealed lead acid battery instead (such as a motor cycle battery). Then depending on voltage required fit a simple rectifier, or a voltage doubler/tripler (3 schottky diodes and 3 electrolytic capacitor) and charge the battery from a DC voltage (Dynamos tend to be AC output) If you need to you could add a voltage regulator. I do this and recharge two sets of 12V batteries whilst riding on summer trips.
everything on my bike uses almost 12v 10,000mA
"(or empty contents in to another dish)" but that would be too easy ;) nice instructable!
i love that cheese
Is there a way you could rig it up to charge some NiCad's without pulling them out?
Sure, you don't necessarily need to pull the individual cells out. If you already have a charger with a single connector, just match it up with your battery pack and plug it in. Use this <a rel="nofollow" href="http://www.greenbatteries.com/batterycalc.html">battery charger calculator</a> to figure out how best to match up a charger to your cells.<br/>
WARNING: Don't use this to make food. Throw out the 'cheese food' and get some real parmesan or romano! For the health of your pet, make sure this goes straight into the garbage. Great instructable, by the way!
Im surprised this was featured without a introductory image of the product but good job!
I read through your racedaynutrition post earlier today - love it and I'm going to do my own version to power my Luxeon headlight. I'll use 3 4-AA battery holders to get my voltage up to 14.4 , with an extra independent pack to drive my taillight. I love the enclosure - I think I'll leave the label on mine for as long as it'll last on the trail.

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