Block heater in the summer time

[mixu-]

Where I'm from the summer mornings are pretty cool. Typically when I go to work I'd expect maybe 10C (50F) in the morning. I've noted that the small 1.3l engine of Honda Jazz takes about 1,5km (1 mile) to reach the level of "not-so-terrible" efficiency. During that distance it consumes twice the gas it usually does. I lose about 5l/100km worth of efficiency for that distance when the engine is cold.

So that got me thinking how to reduce that distance - to zero even? And now I have! This morning I plugged in the 550W block heater and had it on for about 2 hours. When I got in the car the engine coolant was already at toasty ~50C, instantly giving me good mileage.

Doing the math:
Electricity: 550W * 2h = 1,1kWh = 0,11 euros
Gasoline: 5l/100km * 1,5 km = 0,075l = 0,11 euros (1,5€/liter)

So in my case 2 hours is the break-even point. At 2 hours it doesn't really make a difference if I use electricity or gas to warm up the engine. More tests will follow to see if I can find an optimal time for pre-heating. There might be a sweet spot somewhere around 60-90 minutes? I'm also interested to see the impact at the fuel pump.

[gone-ot]

Same "efficiency" works here in Arizona...use heater in A.M. to ensure immediate warm-up and highest vehicle MPG...right from the start.

As you mention, the only question is "how long" warm-up is needed and is it cheaper than the gasoline savings.

[Daox]

Yep, block heaters even in the summer can produce great results, especially for those with short trips.

[Gasoline Fumes]

I use my block heater all year!

[TomO]

I use the EBH on my subaru quite often in the summer as well.

[Ecky]

I use my block heater when I have opportunity. Warmup time on the Insight's 1.0 is pretty short because it has a water jacket over the header, but the math still works out in favor of using it.

Does anyone know if there's any point in using a block heater with a daily driven Prius, due to its hot water reservoir?

[Daox]

Yes, it still helps a fair amount. The Prius has a pretty horrific cold start penalty. You can't EOC and other things unless its warmed up.

[NoD~]

Another one to point out is a heater pad on the oil pan. I did this recently and noticed even further improvements in MPG on my short drives, as well as better idle.

I plug my car in every night and have a timer setup to warm up my car for about an hour or so before I leave. Anything more than this doesn't give much benefit in heat. (though, I should do another graphing session on these temps for VS ambient temp, that would be interesting...)

[PaulB2]

I had an oil pan heater on my previous car. I connected it to an X10 circuit so whenever I got up in the morning, the first thing I would do was to push the button turning on the heater. By the time I got out to the car it had had about enough of a warmup. This is another thing I need to get done for my current car.

[mixu-]

I've been collecting data via the OBD2 port for the past month now, and here are some interesting results. I'll let you make the conclusions.

I filtered out all trips shorter than 5 kilometers.