I have just recently purchased three trail cams. I am wanting to hook up and external power source. I notice that most trail cams take four C batteries, which should operate on 6v. But when you buy an external power souce from the mfg., they are 12v. I can rig my cameras to operate on either one. Which one would be better 6v or 12v? I read that several guys have use small lawn mower batteries. Question, don't they have too much amps that could damage the cameras?