Heaters powered by the 12 volt lighter socket or 12 volt accessory outlet in your vehicle can really come in handy when the factory heater stops working. The trouble is that there’s a limited amount of power available from the lighter socket in any vehicle. Everybody knows that it takes a good amount of power (AC or DC) to generate a reasonable amount of heat. This is of course why most homes don’t use electric heat.
There are many 12 volt heaters for cars which can really help out on those cold foggy days. Some plug into the vehicle’s lighter socket outlet and others require a connection directly to the vehicle battery.
It’s impossible to produce more heat using power from the vehicle’s 12 volt outlet because the outlet can transfer only a limited amount of power. This is restricted by a fuse in the fuse block. This power limitation CAN NOT be remedied by using a larger fuse in the fuse block. Do not do that! The wiring that leads from the fuse block to the accessory outlet is not sufficient to handle more power than the manufacturer has it fused for.
To help put this into perspective, let do some math. The vehicle operates at 12Volts, the lighter socket outlet is fused with a 10 amp fuse. The most heat that can be produced is 120Watts. In some cases the outlet will be protected by a 15 amp fuse, that’s great. In that case the most heat that can be produced is 180 Watts. This is roughly a tenth of the heat put out by a professional hair dryer. Doesn’t sound like much, but it still makes a huge difference when the heater goes out in your car or truck and it’s 10 degrees outside.
These small DC powered heaters do a great job at defrosting the windows. They can warm the entire vehicle, but they need a little time to get it done. In that time it is recommended that the vehicle be left running or you may need a jump start.