I'm currently attempting to design a circuit that can step down an 18.5V lipo battery into independent voltages of 12V and an indeterminate number of 5V lines, which will be powering various pieces of equipment. At this point I'm still pretty much in the early conceptual stages, so I'm not too worried about the precise specifications. What's the best way for me to step down the voltages as efficiently and safely as possible? I was thinking of using an op amp buffer system (LF353 or something similar) or just plain getting a regulator (LM78XX) maybe wiring a capacitor or two in parallel with the output and ground. Unfortunately the 18.5 V to 5V, and even the 18.5 V to 12 V drop are probably way too high and would cause overheating, especially when you take into affect the possibility of an overcharged battery. I could step the power down gradually with multiple regulators but it seems a roundabout solution. Any suggestions?