A bit late in the conversation...but...
Protected batteries pretty much have a fuse that prevents over a certain amount of power (amps) being drawn from the battery at one time. Usually, it limits it to 10A, and is seen on a lot of older chemistry batteries to keep them from overheating. If you get a good battery that can support a higher amp continuous discharge without overheating (IMR), you shouldn't need a protected battery.
Of course, safe use is the best defense. Make sure your batteries are in good working order. I prefer to use regulated mods to prevent shortages, use known good safe chemistry batteries and buy from a reputable source (there are a lot of fakes out there). I recommend using a regulated device (Variable voltage/wattage) for added protection, but if you use a mechanical mod (no electronics whatsoever), read up on how to do things safely and ask PLENTY of questions until you fully understand what to do and what to avoid before attempting to use a mechanical mod.