SpudFiles

I get the feeling you really shouldn't need that much power to get a healthy spark. A high voltage system is basically just exchanging current for voltage, and it delivers enough juice to fire a spudgun off a relatively small battery.

The easiest way would be to probably just experiment and see how little current you can get away with.

I'm assuming you're going to be using a capacitor anyways, so even the smallest battery will make it fire, but charge times and how long the battery will last are a different story.

How about using a flexible solar panel wrapped around the barrel? Kinda out there but that would be pretty awesome.

dewey-1 wrote:jimmy;

I have to disagree with you on Ah not being important.
It is based upon how much time the battery can supply the current you are demanding and how long before recharging for a given Ah capacity.

Back in the old days of RC car racing, all we had ....

I think where you are going wrong is thinking in terms of a device that operates continously, like an RC car.

In the sparker application the battery will be supplying power for a fraction of a second and then not supplying any power for a few minutes while the gun is reloaded. The key characteristic of a battery in this application is how much current it will provide for a short pulse.

Heck a 1000mAH NiMH battery will provides hundreds of 1 second long pulses at 10 amps. A 2000mAH battery would do twice as many but so what? Hundreds of shots from the battery is still adequate and probably more than you would do in a given shooting session anyway.

So the mAH rating is only marginally important since the duty cycle of the battery is going to be so low. The most important thing is that the battery can provide a high current pulse for a very short time.

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Thanks for all the comments while I was gone, guys. I've been doing our annual inspection, (JROTC).

As I've already PM'ed dewey-1 about, I've been playing with the idea of powering the ignition coil off the pulsed output of an induction coil. I can get induction coils out of "toys", (shock lighters), that cost a few bucks, and they run off AAA batteries. I don't know how this will work, but we'll see.

I'm still looking at the gel cell idea. If the induction coil doesn't work, I'll resort to buying a battery similar to Jimmy's link, although it might be salvaged from somewhere, and not bought new. The whole "gel cell" name was throwing me off. The State Police here have hundreds of those batteries, (some still good), lying around waiting to be recycled. I've seem them in my dad's trunk before, (not hooked up). I'll see what I can find there.