How long can i leave the block heater plugged in?

 

As long as you don't mind paying for the electric.
Most block heaters are in the 1000 watt neighborhood.
The smallest one I have ever seen was 600 watts.
The biggest one was 1500 watts.

 

since my wife don't see the electric bill, i plug mine in when i get out of the truck at night if it's below 50 degrees and don't unplug it until i get ready to drive it the next day. i know it probably don't need that long, but it sure does make it crank better(that is when it is cranking..got to replace batt. cables) and i figure what she don't know won't hurt me. LOL

speedrdr

 

When I was driving my truck every day I had mine plugged into a timer. It would turn on about an hour or so before I would want to leave. Worked great and I didn't have to worry about the electric bill.

 

i use a timer also works good!! it comes on about 2 or 3 hours before i go to work depending on what time i am leaving that day. i think anything over 3 hours is over kill. just make sure you have an extension cord atleat 12 gauge maybe even 10 if your far away from the outlet.

 

Here is some great information about block heaters. If I remember right Dave S. is a master electrician. He and many others posted some very important information on do's and don'ts with block heaters.

https://www.ford-trucks.com/forums/5...er+electrician

 

Do use a short extension cord with large wires.
Don't use a very long small wire extension cord.

If the extension cord gets warm when the block heater is plugged in, the cord is to small.

12 AWG extension cords are good for less than 50 feet.

 

it got in the low 30's last week,no problems cranking,but is it better for the truck to plug it in?

 

Yeah I got a myself a heavy duty Timer and usually set it to start heating two hours before I take off in the morning. Also got a 1500 Watt cab heater on a timer. The truck is usually nice and toasty (included defrosted windshields) by the time I leave for work at 5:45am.

I don't even notice the extra electric costs with the timers the usage is negligible compared to all the benefits of a warm cab and better starting.

Seb...

 

It all depends on what weight oil you are using. 15W40 starts getting pretty thick at 25 deg. and takes longer to crank. Cranking is what hurts the truck.
I switch to 10W30 when the temp is going below 25 for several days. I also use a timer on the block heater. Don't hardly notice it on the electric bill.