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What is a good reliable way to hook up batteries to circuits? I know there are 4 AA battery holders, but what if I need to hook up a bunch of D batteries?

there are holders for multiple D batteries i have seen ones that hold four
if you need more you could make your own holder

robotman09 wrote:there are holders for multiple D batteries i have seen ones that hold four
if you need more you could make your own holder

I was at Radio Shack today and they only had ones that hold 1 D battery. So where would be the best blace to buy one and/or what would be a good way to make some?

well the only place i have seen them is at radio shack hmmm
i would try a hardware store if you want to buy one i dont really have a way to make one that i feel comfortable sharing (not sure how well it will work)

If your radioshack doesn't have either of these, you might have another local radioshack that might? Mine always had them...
http://www.radioshack.com/product/index ... Id=2062245
http://www.radioshack.com/product/index ... Id=2062243
You can always buy them online if you really need one or string together the single holders.

I think it would be a good idea to invest in some type of rechargeable battery. The initial cost may be higher, but over the whole season I'm positive you will save money (especially if you have any high-amp items running in the machine).

Lead acids, which are what I would normally recommend, are not allowed, but there's still NiMH, NiCd, the various Lithium-ion rechargable technologies, rechargeable alkalines, and others.

Below, the term "cell" to refers to a single flashlight-type battery. The term battery refers to 2 or more cells connected together in either series or parallel.

An easy/inexpensive way to make a battery by connecting cells in series:

1. Lline the cells up in a row on a sheet of paper.
2. Roll the paper tightly around the cells to form a tube and use tape to keep the paper from unrolling.
3. Cut the paper so the tube extends a little longer than half the diameter of the tube past each end of the batteries.
4. Remove about 2 inches of insulation (the length is not critical) from 1 end each of two pieces of wire (i red & 1 black is a good choice, but they can be any color and don't have to be different.).
5. "Wad" the bare part of the wire into a ball.
6. Put a slit in the tube, place a ball of bare wire so it contacts the terminal on the end of the battery and the wire extends out of the slit.
7. Insert a piece of foam rubber in the tube over the ball of wire.
8. Fold the end of the paper so it closes the tube and compresses the foam to hold the wire in place.
9. Use tape to keep the end of the tube closed and the foam compressed.
10 Repeat for the other end.

This may not be the very best solution, but the price is right if you want to use individual cells.

You now have a custom battery with however many cells you wish. If the battery is too long, make 2 or more shorter batteries as described above, tape them together side-by-side and connect them together in series.

Using this method for batteries with cells in parallel requires making a tube with wires attached for each "branch" of the battery, taping the tubes together side-by-side and connecting the wires to form a parallel circuit (all positive terminals connected together and all negative terminals connected together.)

Note: For best results, all cells should be of the same type and manufacturer. A drawback of this technique is that you have to start over each time you need to change the cells. Rechargeable cells, unless your battery has the correct number of cells, will require you to remove the cells of have a custom charger to recharge them.

As mentioned above, some type of secondary (rechargeable) cells are the way to go if you can afford the initial outlay. One drawback is they don't have as large a capacity as many primary (non-rechargeable) cells. The will need to be recharged sooner than the non-rechargeables would need to be replaced.

DigiKey lists 1, 2, 3, 4, 6 D-cell holders. They probably have a minimum order.

I have found that remote control car battery packs, you know the rechargeable ones work very well. I have even modified the wires to turn on and off. I have a 9.6 volt one for my resister and it works like a charm.

I read about some solar panel in the rules. Does anyone know where I could get one?

There are no solar panels (photovoltaic cells) in this event. The national clarification on soinc banned them in favor of photosensitive resisters.

Forgive me for my ignorance, but can you tell me more about photosensitive resisters and what sort of store I can purchase them at?