High output - modded block heater …

Discussion in 'General' started by xcel, Feb 27, 2007.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    ___We all know the importance of a block heater in its attempt to reduce the cold start hit we all face and especially those of us in the northern states in the winter months. My question is more along the lines of a super heater. Not anything that is going to punch in 1,500 W for 10 hours and bring the coolant temp up to 180 degrees but maybe a 500W heater attached to a timer that would bring coolant up into the 140 degree F or more range vs. the 95 - 110 degree F range of a normal block heater thus alleviating much more of the cold temp hit. Block heaters were not designed for FE savings but were designed for adding just enough heat so a starter could turn the car/truck over and get it running in the coldest of temps. We are looking at them for a far more advanced purpose and one I think is worthy of pursuit. Again, there is a problem in punching out 1,500 W for an ungodly amount of time but maybe 15 minutes before leaving the drive or garage at 500 W would make the power consumption worth our while? Some calc’s would have to be done to make sure we are not causing more emissions w/ a high output heater but I was wondering out loud given the many Insight’s, Prius’ and HCH-II’s sitting in that sub 30 mpg range for 3 + minutes this past winter during the worst of it.

    ___Anyone seen or heard about anything like this?

    ___Good Luck

  2. brick

    brick Answers to "that guy."

    Well, as far as I understand a block heater is just a simple heating element. Hook up a good one to a variac and some instrumentation and you should be able to crank up the power simply by driving up the voltage from the nominal 110-120VAC. More electrons more heat. I don't know how long it would last under that kind of use but I guess it all depends on how efficiently the heat is dissipated to the ICE.
  3. hobbit

    hobbit He who posts articles

    One problem, especially if it's windy, is a lot of heat
    loss from the block. The Toyota block heaters work pretty
    well and bring the heat right around the combustion area,
    but on a cold windy day I can't get the thing much above
    20C even with the hood closed.
    What's really need for the prius is a *battery* heater.
    One of those resistive pads right under the box, maybe.
    And that would be sheltered out of the wind..
  4. highwater

    highwater Well-Known Member

    I have one of those under desk foot heaters, that you might fine at the office supply stores, that I layed on top of the spare tire in the Insight. I plug it into my timer (2hr) along with the block heater. 115vac, but I don't remember at the moment what the watts is. In a closed garage, it will have the batteries in the mid 40F range, even with the coldest of days we have had this winter, in Okla.

  5. Bruce

    Bruce cheapskate

  6. philmcneal

    philmcneal Has it been 10 years? Wow

    MAN and i was reading some guys with the classic prius had their block heaters as toasty as 49C... man 20C is pathetic ARGH!!!! Toyota better not take more than an hour and a half to install mine tommorow or i'll be grilling them like no tommorow.
  7. Bruce

    Bruce cheapskate

    Re: High output - modded block heater …

    This thread is making me think...I could probably use one more for engine longevity than for FE, but I need it most at work. It's about 3/4 mile from my parking spot at work to the merge onto the expressway. Even though I take care to noodle along in second at 15-20 MPH getting there, it's still stone cold when I'm merging on...and right after that, I need to start going uphill at 45-50 MPH. The automatic won't even get out of fourth until near the top, let alone lock the torque converter.

    I'm thinking I should get an Optima battery, plunk it in the passenger compartment with an inverter and timer, install a block heater, run it off the battery and charge it at home or from the cigarette lighter with a resistor and diode. The increased FE might not pay for it, but the engine longevity might.

    I'd need to make sure to get out of work on time...the battery would probably only last 15-20 minutes at most with a 300W heater. Perhaps a 60W dipstick heater would be a better choice for this setup.
  8. msantos

    msantos Eco Accelerometrist

    Re: High output - modded block heater …

    Our block heaters are typically rated at 400-450 watts already.
    In order for the block heaters to make a significant difference in my cars I need to have the block heaters powered up 4-5 hours before leaving the garage in the morning. I actually have them on an Intermatic timer.


    I too have briefly wondered about this, and then concluded that much of the heat actually gets radiated into the garage (floor, rest of car and garage ceiling). I even took temp measurements of these different areas and noticed the "waste". Would adding a more agressive heater help someone like me - particularly when the temps dip to -40? Perhaps, but I fear that it would be a classic case of diminishing returns.

    I firmly believe block heaters should not be optional. I've had them in every car and I swear by them for because of the FE benefits as well as the enhancement to engine's life. And on this note I feel it is worth the electrical power to use them.
    If I had higher rated block heaters installed (if we could have them) then I fear it would not be cost effective anymore. Then again, maybe I would only need 1 or two hours for an equivalent effect.


  9. Bruce

    Bruce cheapskate

    Re: High output - modded block heater …

    I have yet to see an argument that a block heater would yield an overall decrease in energy cost or emissions in my case.

    For energy cost, let's consider that my current best (last) segment on my morning commute is 46 MPG, whereas the overall commute is about 40 MPG for about 15 miles. If a block heater were able to give me the FE of my best segment for the full commute, it would save 15 mi/40 MPG - 15 mi/46 MPG = .05 gallons of gas. (This is a rather liberal estimate, since the majority of losses at the speeds I travel (ave. 30 MPH) are from rolling resistance rather than aero losses, nearly all of rolling resistance is from tires, tire inefficiency is about double when cold and tires take about 20 minutes to fully warm up once at speed.)

    .05 gallons of gas at $2.40/gallon is 12 cents.

    400 watts of block heater for 4 hours (the low end of both estimates) is 1.6 kWh. My electricity costs $.30/kWh delivered, so the total cost of the electricity would be 48 cents, or quadruple the cost of the gas...that's before the cost of the block heater, and my engine would probably require more heat since it's larger than a Prius'.

    Emissions gets a bit trickier to argue, but I do know that when you use electric heat, about 1/3 of the original fuel's energy content (mostly coal in the US) is converted to usable heat after generation and transmission. In a car, only about 15% of the energy consumed at best is converted to mechanical energy (which is then converted to heat in the wind and tires), so 85% or more of the fuel content is converted to heat. Granted, a lot of it goes out the tailpipe, but that still leaves a lot left over for heating up coolant. The energy content per CO2-generating content of fossil fuels varies a bit, but probably not more than 50% or so.

    The inefficiency of power generation is the principle behind micro-combined heat and power, or micro-CHP for short. The idea is that you use your home heating fuel to throw a little electricity into the grid, and use the waste heat to heat your home. Overall, this is much more efficient than using a bunch of fossil fuel to make a bunch of waste heat right at the power plant only to make more heat from fossil fuel to heat the home:


    It could be argued that no CO2 would be generated from wind, solar, geothermal, nuclear and tidal sources and that purchasing energy from these sources would yield no emissions, but supplies of this energy are limited at present, so this would merely shift the burden of CO2 generation to a different consumer. Perhaps the most efficient and cost-effective way at present to preheat the engine using solar power would be a car cover that's colored black over the engine compartment...hmmm, perhaps that's not a bad idea for work...

    My solution for now has been to capture radiator losses by parking my car in an insulated container (the garage). It probably doesn't benefit FE as much as a block heater, but it doesn't require any additional operating expense or energy expenditure either. Circumstances may eventually require me to move it back outside, but it's a pretty decent compromise for now. As best I can tell, it gives me a better bottom line for cost, energy expenditure and emissions, but not bragging rights.
    Last edited: Mar 12, 2007
  10. msantos

    msantos Eco Accelerometrist

    Re: High output - modded block heater …

    That is a good point Bruce. One that I am all too familiar with, particularly with some friends who live south from me. They've done the math and they too do not see the advantage all that clearly. It could be because of any number of reasons including the cost/kw, cost of gas, and overall average temperatures. I guess block heaters may not be optimal for all people in all circumstances.

    In my case (and others like me), the use of a block heater is a fact of life. And because my province produces a surplus of hydro-electric energy all year round (much of it is exported east and south) the prices per KW are very low, thus making the use of a block heater a no-brainer. In fact, I make strategic use of the block heaters during fall, winter and spring which allows me to have pretty good city only mileage and still save and polute less overall. Because the eletrical source is clean my net pollution remains the lowest possible during the winter months when I use a block heater.
    Then again, northern living requires the use of a block heater at least during the winter months as a demostration of sanity. Anything else is asking for trouble.


  11. Bruce

    Bruce cheapskate

    Re: High output - modded block heater …

    I won't deny you that...I've made several trips through WI and MN in the middle of winter and seen plenty of plugs hanging out of grilles. Fortunately, they also have the infrastructure to support it (places to plug in.)

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