I have the watercraft/marine version "Battery Buddy" in my ski-boat. It has saved my bacon on countless occasions, and you definately don't want to be out on the open water with a dead battery!!! Most vehicles have things that always draw power; namely the clock on the stereo is the biggest culprit. The "Battery Buddy" is best for vehicles that are operated infrequently (like a boat); situations where it may be hard to get an actual jump from another vehicle (like a boat), or isolated locations such as a boat marina without a nearby electrical outlet (like a boat).
For cars that are driven daily, the "Battery Buddy" is really not necessary. Stored cars (garage queens) should always have a high quality Battery "Maintainer" plugged into an electrical outlet at all times anyway, thereby keeping the battery at full charge capacity. Every vehicle in my detached 8-car capacity 1800SF garage/shop has a high quality Battery "Maintainer" plugged into it (always ready to go).
As far as battery brands, I've always used Sears DieHard's over the past 30+ years in all of my many vehicles (cars & boats) with great success. There is always a Sears (& now K-Mart) nearby, and their build quality, high CCA rating and battery warranty on the entire DieHard line is the best in the industry. I've never used Optima due to their very expensive price. The Sears DieHard (also @ K-Mart) gets my vote everytime for ease of purchase availabilty, high build quality, great monetary value, high CCA rating, and the best warranty in the business.![]()