Plugging in Vehicles

Plugging in your vehicle, it’s as much a Saskatchewan winter tradition as getting out your snow boots, or thinking about moving somewhere warm.  But it’s something that many of us over-do.

There are three good reasons to plug in your vehicle:

  1. To be sure the vehicle will start even when it’s extremely cold out.
  2. To reduce wear and tear on the engine.
  3. To be sure the vehicle runs cleanly and efficiently.

However, plugging in warms the engine with an electric heater, and I don’t know if you’ve heard, but three quarters of Saskatchewan’s electricity is produced by burning fossil fuels.  Almost half by burning coal.  So we need to reduce our electricity use as much as we can.

So, how do we balance the benefits of plugging in our vehicles with the benefits of reducing electricity use?  I looked at a wide variety of sources for this.  Natural Resources Canada, CAA Saskatchewan and Manitoba, a co

uple of vehicle manufacturers, auto service centers and vehicle magazines.  Basically, they all tell the same story.

What does plugging in do?

When our vehicle gets really cold, the oil in the engine gets thick, and doesn’t do a good job of protecting the moving parts from each other.  A block heater warms the coolant in the engine, which then warms the engine and the oil.   When the engine is warm, it starts easily; the oil is liquid and properly lubricates the engine; the engine runs more efficiently and, as a bonus; the warmer engine warms the air blowing through the vents, so the vehicle’s interior warms up faster.

At what temperature should I plug in?

A well maintained vehicle should start at ‑30oC, but it’s hard on the vehicle, and the vehicle doesn’t run as efficiently.  Using a block heater when it’s ‑20oC improves the efficiency of your vehicle for a standard urban trip by 10%.  Using a block heater when it’s ‑25oC increases your efficiency for that trip by 25%[i]

All of the sources I saw suggested plugging in when the outside temperature is below ‑15oC or ‑20oC.

I looked at what the weather has been like this winter.  In Saskatoon, there are 25 days this winter that the temperature has gone below ‑15oC.  and only 10 days that it has gone below ‑20oC. (I’m writing January 11).

How long do I need to plug in for?

Most sources suggested plugging in for a maximum of 2 hours.  Only CAA and SaskPower suggested longer, and they said 4 hours.  Honda said 30-50 minutes![ii]

What will I save?

That of course depends on what you have been doing.  If you have been plugging in the vehicle when you get home from work, and leaving it plugged in until you leave for work the next day, from November through March, you could be spending $125/year on the electricity for your block heater.  If you change to plugging in for 2 hours, on the nights that the temperature goes below ‑15oC, you would spend only $8.  And the savings in greenhouse gas emissions would be 740kgCO2e.

At our house, we don’t use our vehicle every day, and we park it in an (unheated) garage, so we rarely plug it in.  When we do, we use a timer, that is set to come on one or two hours before departure, depending on the outdoor temperature.

[i] Natural Resources Canada.  Vehicle Warm-Up. Accessed on-line 11 Jan 2016.

[ii] Honda West A New Direction in Driving.  Ask the Expert – How Long Should I Leave My Vehicle Plugged In?  Accessed on-line 11 Jan 2016.

Angie 220 photo

Angie Bugg manages energy conservation projects for the Saskatchewan Environmental Society, and is an active member of McClure United Church. You can contact her at “The earth is the Lord’s and all that is in it, the world, and those who live in it.” (Psalm 24:1)


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