Transient power supply needs

tek_man

I am making (another) automotive type board using a BS2 to control igniton coils. I have the program and circuit working. I am currently using a small lawnmower battery(12V) to power the circuit due to the amount of current the ignition coils can draw (up to 8 - 10 amps @12V) for some coils. This peak current·ramps up from 0 -8amp·in about 2mS and then releases the circuit, and that brings me to my question. I travel by air frequently and the airlines dont much care for batteries (lead-acid). a 10A power supply is bulky(and expensive). I have a power "brick" rated at 12V 2.5A that is small and would travel nicely. I know that you can, and I have, used capacitors to clean up a power supply and filter out the noise. I also know that caps are capable of storing and releasing current. Would it be feasable to use a large capacitor to supply the coil with current for short periods of time? The effective duty cycle of the circuit is less than 10% so the caps would have plenty of time to charge up between firing events. Any ideas on how large the cap would have to be to suplly this abount of energy (I really don't want to get one of those high dollar 1 farad caps people use for their automovie boom boxes either)

Is this a realistic thought, or should I come up with something else?

Thanks for reading

Lee