Block Heater or Grill Block?

15 kWh is way more than actual measured electricity use. The EBH is temperature controlled and uses less power when hot. I have been making measurements for over a year (~400 uses) and it takes only a little more than one kWh each time.

 

2009Prius, thanks for the info.
One kwh is quite reasonable if most of the S1-S3 phases are taken care of. I am curious though, what is the mechanism of temperature control ? I thought the entire device was a cord and resistive element at the end.

Oh crap, I just realized a serious error in my calc. It is not 400*120*3, it is 400*3 = 1.2 kwh. Sorry, guys.

 

I think it's a simple on-off thermostat.

 

I wouldn't bother with either if I were you, OP.

4.5l per 100km is great. Better than most.

 

I installed the EBH on mine and it really helps shorten S1.

 

I know this is an old thread, but those numbers are wrong.

It is 1.2 kwh, from (400w * 3h = 1200wh = 1.2 kwh). 1gallon (US) of gasoline is 36.6 kwh. So more like .03 gallons
of gasoline.

But it still does not make sense to use the block heater, at least, not for me.

At $0.17/kwh the electricity would be $0.204. Currently gas where I am is ~ $4/gallon. Let's say that the first 5 minutes not warmed up is 25 mpg, and warmed up is either 40 or 50 mpg. On my normal route the first 5 minutes is a distance of about 1.75 miles. So gas used not warmed up 1.75/25 = .07 gallon and warmed up 1.75/40 = .044 gallon or 1.75/50 = .035 gallon. Cost for the first five minutes (in gas) is $0.28, $0.176, or $0.14. Difference is either $0.104 or $0.14. Both are less than $0.204. The bottom line seems to be that the block heater would not be an economic win even if it was free to buy and install. This is from a Southern California May starting temperature. Clearly the block heater makes sense when one would need that on any car, and it might make sense in locales which are cold, but not quite that cold. For "nice" weather, it does not seem to add up.

Disclaimer - these are all estimates!

 

Your cost calc agrees with the online calculator I found here:

Electricity bill calculator | Energy cost calculator

Your case:


Comments:

1. Temperature will rise about 25C, and plateau at the level, within about 2 hours. So that last hour is pretty much superfluous. Rewording your case with just 2 hours use, the cost per use would drop to 13.6 cents. Further regarding that 25C rise: that's all it is. It doesn't fully warm up the engine, just gives you a good head start. Further complicates any calculation though.

2. There's more to it than just economic "making sense". Even if you just break even, faster warm up is good for the environment, makes the cabin warm up faster in winter, is easier on the engine, and so on.

FWIW, with our cost per kwh at around 9 cents (CDN), the cost per use is 7.2 cents.