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block heater economics

Discussion in 'Gen 2 Prius Accessories & Modifications' started by J&K, Jan 11, 2008.

  1. J&K

    J&K New Member

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    As a newbie, please forgive me if I'm asking a foolish question, but are the econonomics of a block heater easily justified?

    Here is our situation: a normal workday will consist of my wife driving the Prius about a mile to work (no, she can't walk because of a disability). In that situation is it worthwhile to heat the block? Our location is mid-Ohio.

    Thanks, for your advice, Jim
     
  2. edthefox5

    edthefox5 Senior Member

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    I would say no...not a good value unless its a crazy cold year up there. But the EBH is only about $ 70 delivered and a pain to put in but not if your young and are handy so its not outrageous. In the winter without a warm block the ICE will never shut off within a mile and being such a short hop your going to get pretty bad mileage. In the summer you might be able to EV the whole way though. Then your talking!
     
  3. qbee42

    qbee42 My other car is a boat

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    I wouldn't bother in a southern location like Columbus. It's just not cold enough to make much difference. Some people, like Evan, live even farther south and still use EBHs, but then some people are nuttier about mileage than others.

    Speaking of Columbus, I used to live in Old Worthington, right behind the Worthington Inn.

    Tom
     
  4. Neicy

    Neicy Member

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    I have to disagree with the others. I have a shorter commute, and I think it helps even in the spring and fall. Unless the outside air temp is always at 90F, it will help. And I have not seen a difference in my electric bill, so it can't be costing that much to run it. The reservoir keeps the coolant a little warmer, but as soon as it hits the cold engine it goes right down and has to be reheated. With the engine block heater you don't see that dip nearly as much, and my temp by the time I leave my driveway is over 100F in the middle of winter and even warmer the rest of the year. I got my EBH through a group buy in the Priuschat shop for $39.00 and FireEngineer installed it for me in the fall during his East coast trip for which I will be forever greatful. This is just my opinion, but I think there are others that would agree.
     
  5. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i have to agree that you need to examine your driving habits and the conditions your car sits in when parked. if outside, an EBH would be nice. even uninsulated garages can keep a car several degrees warmer.

    multiple short trips, if planned, can be a huge boost to the mileage. EBH in reality only use pennies a day so a 10% increase in mileage say going from 5 to 5½ cpm will pay for itself in just two short trips a day. (keeping in mind, that economy on very short trips without EBH might be more along the lines of 20 cpm!! using one can say increase you to 10 cpm saving you the electricity in just a few miles.)

    mind you, its all dependent on your electricity rates. i live in a cheap area, some places like CA might not be worth it especially if in temperate climates. i personally think Ohio is waaay more than cold enough to benefit if short trips are common
     
  6. JimboK

    JimboK One owner, low mileage

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    I agree with Neicy and Dave. I'm in central VA and I use it year-round (when I have somewhere to plug up). The substantial improvement in MPG for the first 5-10 minutes after a cold startup more than offsets the electricity cost.
     
  7. Rxmxsh

    Rxmxsh Member

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    I would say yes - that it is worth it. I have a short commute of 2 miles to work (I'm just lazy though). Usually this is about 10 to 15 minutes of drive time. My mileage dropped significantly w/the cooler temps here in SoCal. So I bought the EBH and installed it today. From what I understand, it'll be worth it, bringing my average in the first 5 minutes from 12.5 to about 45...

    Also - Godiva has one installed and she's in San Diego. Regardless of climate, it'll help you out in the first stage of warm up.
     
  8. omgitsroy326

    omgitsroy326 New Member

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    is there anyway to have this tap into the car battery? i'm in condo and shared parking with no electric outlet...
     
  9. J&K

    J&K New Member

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    I think I'll do the heater. It may not be worth it for a short trip, but the Prius will be our main car for evenings and weekends. The cost appears to be modest.

    Do group buys for the heater come around regularly? How initiates them?

    thanks, Jim
     
  10. Rxmxsh

    Rxmxsh Member

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    Not sure on the group buy, but it's $59 and I didn't pay shipping.
     
  11. patsparks

    patsparks An Aussie perspective

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    It will reduce petrol consumption but increase real running cost because the cost of electricity to run the EBH for 3 hours will be more than the cost of fuel for the entire morning commute.
    At about 10 cents per kilowatt if you run the EBH for 3 hours you will use about 15 cents worth of electricity each morning. If you cover 1 mile each morning at say 25mpg and pay $3.00 per gallon you spend 1/25th of $3.00 each morning and each afternoon so just in the morning you use 12 cents worth of petrol so no matter how good you get your mileage you won't save 15 cents from 12 cents of fuel. EBH won't work for you, sorry.

    Just enjoy better mileage than anyone else driving 1 mile each way.

    Even someone who drives their first 5 minutes at an average speed of 30mph at 25mpg will cover 2.5 miles using only 30 cents worth of petrol, if they double their mileage they only just cover their electricity cost of 15 cents per morning and no saving off the cost of the EBH.
     
  12. Godiva

    Godiva AmeriKan Citizen

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    Absolutely. I can pulse and glide a lot sooner than I used to be able to do in the morning. BTW temps when I leave for work on in the 40s now.
     
  13. qbee42

    qbee42 My other car is a boat

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  14. JimboK

    JimboK One owner, low mileage

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    This addresses an issue that I didn't consider with the original post: the extremely short commute. Assuming 25 MPG for the one mile (and assuming your math is right), you're right. But 25 MPG may be on the high side for a cold-start 1 mile commute. Before the block heater I typically got in the neighborhood of 25 MPG for the first five-minute segment; the first mile of that is almost certainly lower.

    To J&K: I think your approach still is sound. Assuming the weekend and evening outings you mention are longer than 1 mile, it probably still is worthwhile for that. Then, assuming you get the heater, I suggest a test: alternating days of using the heater on the commute and not using it, during a period of fairly consistent temperatures. Keep other variables (e.g., cabin heater use) constant as much as possible. Document and average your trip mileages with and without. Report your findings here for the benefit of others. Then do the math for costs, comparing to your own electricity cost, and determine whether you're saving on those short drives.

    One added consideration, important to me but maybe not to others: If I break even with the heater, I'm happy. I'd prefer energy money go to domestic energy sources via the electric company than to overseas oil exporters.
     
  15. JimboK

    JimboK One owner, low mileage

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    [Deleted - duplicate post]
     
  16. Gadgetdad

    Gadgetdad New Member

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    Well, yes and no! An inverter could be used to bring 120 volt A.C. to the EBH, but unless you can change a law or two of physics, you would wind up with a warmer engine and drained battery that would use more gasoline to charge it back up! Due to energy loss along the way, the concept would use more fuel than just running without the EBH.

    When I visit a friend in her condo, I plug into a light pole I found in the lot that has an electrical outlet on it. I just pack a 15 foot extension cord into the storage compartment for just such occasions.

    Lee :cool:
     
  17. Slartibartfast

    Slartibartfast Senior Fjord Architect

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    For one mile, I can't say it's worth it, but it definitely improves the overall numbers over the first 5-10 minutes. I've done some qualitative comparisons, but nothing with absolute numbers because I generally drive short distances this time of year and don't have a Scangauge. My numbers are also a bit skewed because I did grill blocking at about the same time. But last night, I took her out without the benefit of the EBH being on and found a noticeable difference, at least in cabin heat.

    In December, I had it plugged in and turned on for about 2 hours before my morning commute. The first three miles or so of my trip is stop and go no more than 35 mph. Even in 10 degree weather, the ICE would stop by the second or third stop sign if I left the cabin heat off, which is about a mile. It would still start right back up each time I applied the throttle until I reached the freeway. At that point, I could turn the heater on as I accelerated onto the ramp and be warm and toasty by the time I reached my destination.

    Last night, I had to go out for an unplanned 2-3 mile trip. It was about 20 degrees and the heater had not been run for days since I had been driving it much less frequently and it has been warmer outside. The ICE refused to shut down at all until I reached the store, even at stops and with the heat off.

    I see a definite benefit after that first mile, but not really before. If you're driving right back or somewhere else, you'll see an improvement on the mile trip back home, especially in tropical southern Ohio because you will be near optimal operating temperature about the time you get your wife to work. If you get yourself some pipe insulation and block the grill, that would be an even better return on your investment.

    Even without the heater, you still do far better than a traditional car. When I make the same short trip in our mid-size Honda, I only get about 15 mpg.
     
  18. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    what you are saying sounds good, but its based on assumptions most cannot make.

    1) thinking you will be up to normal operating temps in ONE MILE??... maybe in florida, but not anywhere else.

    2) 25 mpg is optimistic as well. on mornings when temps are below 0ºC, i'm averaging more like 10-15 mpg on the first 5, 25-40 on the 2nd.

    3) none of this addresses pollution and resources used. power plants are many times more efficient in generating power...if looking at the cost per calorie used in electricity or gas, i think we find electricity wins by an 8 to 15 fold margin depending on how it was generated. not all of us are here for the money, the environment is big around here too.