I have a motion activated camera that runs off of 6 D cell batteries, it also has a plug for an external power source, it is actually a solar pack but only generates power during the day and the camera uses the D cell batteries at night, batteries last about 2 to 3 weeks. What I would like to find out is it possible to step a 12v car type battery down to 9v and use a solar charger on the battery? And if so how is the best way to step the voltage down. Thanks!