I have a project where I am driving a car horn that is rated for 12V@8A. I have a pack of NiHM batteries rated at 9.6V (usually get's up to about 11.3V) total and their spec'ed out to 10A for 8 minutes. I also have an Arduino mega and a Beefcake Relay kit.
There is a point in my program where the car horn sounds off 3 times (ON 500ms, OFF 500ms). However, when the car horn starts, it usually gets through 1 whole sound, then resets the Arduino. Both the Arduino and the car horn are being powered off the same 9.6V batteries.
My theory is, the Arduino is being starved of voltage when the horn goes off, then resets.
I want to know if it's possible to make a small (in physical size) capacitor bank that I can use to keep the Arduino alive while the car horn is being used in short 0.5sec bursts.