I have a quick question on how you're calculating the amount of power required for this solenoid (again I'm new to this stuff).
If I push 12V into the solenoid with 3ohm resistance, then the current draw is 4,000 mA. If I send a 100ms pulse, that's .00003 mA/hour current draw for each pulse (right?).
How is that going to drain a battery so quickly? I'm sure my math is wrong.