There are a number of places and options to consider when you are thinking about why to buy a 12 volt electric blanket. Essentially this is the travel version of an electric blanket when you are trying to find a way to keep the comfort of home wherever you go. Whether it be camping in your trailer, on your boat or if you are a truck driver, these can be great assets. They are small and portable and provide a lot of comfort and heat for those long cold nights no matter where you are away from home.
Consider how much nicer your trip would be if you had a heated blanket on your boat, or if you were on a camping trip and could climb under your 12 volt electric blanket before you went to bed. Or if you are a cross country truck driver who sleeps in the cab, these too can be a great asset depending on where you are going. Think about how easy it will be if you simply take out the blanket and plug it into the lighter socket to power the blanket and then go to bed. It is powered by a simple 12 volt battery that all vehicles seem to have these days.
However, there is a better option. What if you were able to heat from the bottom up and were to crawl into a heated bed instead of under a blanket. Well that is now an option. The Electro Warmth Company makes an electric bed heater that comes in a 12 volt model. It is called a bunk warmer and uses the same power source as a 12 volt electric blanket. However, it heats the entire bed and not just your blanket. It goes on the same as a mattress pad and then it will heat the entire bed from the bottom up as opposed to just resting on you and keeping the top warm. Since heat rises, this seems to be a better option as you will be able to get more benefit from the heat provided.
You also need to look at it from a comfort standpoint as you will not need to feel the wires of the blanket if you are using the electric bed heater. You will also not need to worry about whether the heater will be wasting your battery, as it will turn itself off when it reaches a set temperature. So, consider your options and decide what will work best for you.