True enough, plus think of all the wear and tear that you reduce by having it plugged in.

 

i think i may just not even worry about a timer and just leave it plugged in all the time...just gotta find out how much a KWH is around here

 

You just need your utility bill.

 

When it's 30 to about 40 with no wind I put mine on a timer. When it's what it has been lately, 5F to 20F with a wind chill at night of -5 I put two sleeping bags on the hood to cover the whole hood and two boards to block the wind from getting under the hood and leave it plugged in all night long and I plug it in as soon as I shut it off to try and keep the heat in the motor. It worked so well last night that I blew NO smoke on startup, just steam.

 

On my "turbo thread" I haven't yet completed my discussion of "heat energy" and "heat capacity" but it sounds to me like some basic "thermodynamics 101" calculations using those concepts might be helpful here! The following is a "simplified" approach that I use to estimate how long I need to have the coolant heater plugged in before starting the engine....

Each kWh produces 2,655,224 ft-lbf of heat energy so my 850 Watt coolant heater produces... (0.85)(2,655,224)=2,256,940 ft-lbf ...of heat energy for each hour that it's plugged in.

The specific heat capacity of water is 778 ft-lbf/lbm-*F and the block contains a 70-lbm mass of water so for each hour that the coolant heater is plugged in the temperature of the coolant increases by about... (2,256,940)/{(778)(70)}=40*F!

So if the ambient temperature is say 40*F and I plug in for 2 hours then my coolant gauge should read... 40+(2)(40)=120*F ...and when I start the engine under these conditions this is about the temperature I see on my digital coolant gauge.

My 150 Watt oil heater produces... (0.15)(2,655,224)=398,284 ft-lbf ...of heat energy for each hour that it's plugged in.

The specific heat capacity of motor oil is 333 ft-lbf/lbm-*F and the pan contains a 40-lbm mass of oil so for each hour that the oil heater is plugged in the temperature of the oil increases by about... (398,284)/{(333)(40)}=30*F!

So if the ambient temperature is say 40*F and I plug in for 2 hours then my oil temperature should be... 40+(2)(30)=100*F ...but I don't have an oil temperature gauge to verify this number and I haven't bothered to crawl under the truck to shoot the pan with my IR gun!

The heat capacity of an ethylene glycol water mix is less than the heat capacity of plain water by an amount that depends on the percentage of ethylene glycol in the mix. The heat capacity of plain water is... 778 ft-lbf/lbm-*F ...and the heat capacity of ethylene glycol is... 462 ft-lbf/lbm-*F ...so the heat capacity of a 50% ethylene glycol water mix is... (462+778)/2=620 ft-lbf/lbm-*F ...which is... (620/778)=0.8 or 80% of the heat capacity of plain water.

On the other hand some of the coolant's heat energy is transferred to the block and some of the block's heat energy is transferred to the atmosphere. For the typical conditions I encounter these two effects approximately cancel and my "simplified" approach gives about the correct answer. Of course as a fulltime RVer I try to avoid really cold weather. Higher wind speeds will increase the plug-in time by increasing the amount of heat energy lost to the atmosphere.

 

I live in northern Michigan and two hours on a cold day is enough, three hours would be more then enough.

 

And I thought all the Engineers were over at the Dieselstop......Well done guys !!!!

 

depending where your from, you honestly dont have to plug diesels or gas motors in much, if you have good batteries and glow plugs you dont have to plug them in at all times, to some of you 32 is incredibly cold, no-one up here in my area plugs in then, with gasoline you only have to start plugging in at -15-20 celsius, they start fine, diesels around -10celsius. They start, let them warm up 5-10 mins and drive away. as long as you run thinner oil in lower temps.
i'm against timers as when you do plug your truck in and they fail then what have you got? when i plug in i plug it in until i get back into it.
but at the moment i have the trucks plugged in for the last week every night, (yesterday afternoon temp -33 celsius, today -34, tonight overnite low -37 with wind chill -47) but everyone has there own opinion, if you want to plug in then do it, but if it is only freezing you really dont have to i think

 

^^^^^Exactly what farmb0y said! BTW, it's the "green thing" to do.

 

Well, I just plug mine in at night and not worry about it. When I get in and start the truck it blows some steam and that's it, it's ready to roll.
Here a picture of my truck being covered and the sheets of sound board are to block the wind from getting under the hood. It's ugly but it works.
This picture was taken while the truck was running. I couldn't get the camera turned on fast enough to capture the steam coming out of the exhaust. That's how warm it was :-P

 

interesting