Justin, There are several different types and they all run off of the=20 mains. There is a battery blanket. You wrap this around the battery and=20 then plug it in at night when you get home. It will hold the battery=20 above freezing even in 30 or 40 below zero F temperatures. This will=20 triple or even quadruple the power that is available to turn the engine. There is another type that is inserted in to the engine block in=20 place of what we Americans call a freeze plug. I believe you folks call=20 it a soft plug. Again you plug it in at night and it will keep the=20 coolant at about freezing in 30 or 40 degree f below zero temperatures.=20 This reduces the friction inside the engine and it also makes it easier=20 to vaporize the fuel and to ignite it. Another type is inserted in to a heater hose and it does pretty=20 much what the block heater does. A fourth type is inserted into the oil=20 pan and also reduces friction. It has less impact on the vaporization=20 and the ignition of the fuel but it does help and it reduces wear and=20 tear on the engine. Remember the worst thing that you can do to your=20 engine is to start it. Overnight the oil drains out of a lot of the=20 bearings and there is just a thin film left until the oil pressure can=20 come up. I hope that helps. Thanks, rich! P.S. I have installed countless numbers of all four types! rich! On 11/21/2014 6:49 PM, Justin Richards wrote: > Not a lot of call for pre-heating in my area (perhaps pre-cooling). So I > am curious how the block heaters work. Do they run off the car battery o= r > mains. Do they also warm the cabin or just the engine. Do they warm the > water or the block directly. Do they remain bolted to the engine or do > they get removed before you leave. And do they take time or done in a few > minutes. > Justin > On 20/11/2014 11:47 PM, "Herbert Graf" wrote: > > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .