... do you folks use in your launch controllers? Do I need a large car/UPS battery, or I can do with something smaller, to fire an igniter?
You could use one of those batteries typically found in the model airplane field boxes, they're powerful and they can be recharged! Ni-cad and Li-poly model airplane batteries could even work too.
That's not correct. Lithium-ion and lithium polymer batteries are quite safe as long as they are not overcharged, physically damaged to the point of developing internal shorts, and are properly packaged.Ni-Cads could work, but Li-Polys are a big danger. With gel cells and car batteries, you can have a short at the pad while holding the launch button and nothing too bad will happen unless you hold it there all day. With Li-Polys will fail catastrophically when subjected to this kind of torture for more than a fraction of a second, (and we know what happens when you get a misfire: "Oops, didn't work. Let's hold the launch button in for 10 seconds, then see what's wrong.") A melting/venting/burning Li-Poly is the last thing you want a couple inches from your hand.
Ooops, sorry about that! I was under the impression that it was over-current, not over-charge that caused the fatal damage. I have not used them yet for fear of my mishandling them and causing a fire. Good to know it only happens when charging.
I do know that the electrolyte in NiMH's is flammable from experience, but that was a very high-gee crash on a DBF competition aircraft (thankfully not ours). The batteries (very high cell count, 20-30V range) broke from their mounts and hit something more solid than them inside the airframe. There was nothing left but ash and small bits of metal within about 3 or 4 minutes.
Anyways, sorry for the misinformation.
however the hazard is a heat burn, and not a flame.
This will not happen with lithium polymer batteries since the electrolyte is not flammable, but it is possible to get a severe skin burn from an internally shorted lithium polymer battery.
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