Pre heating the cabin

Discussion in 'Gen 3 Prius Main Forum' started by spudnut, Dec 3, 2020.

  1. spudnut

    spudnut Active Member

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    I park my '13 PIP in a unheated garage, 95' away from the house. I live on a mountainside and have a 1200' descent for the first few miles, so cabin heat is slow in coming! The block heater I recently installed helps, but not enough. So, I bought a small 750/1500 watt ceramic electric heater, and a remote controlled power outlet, both for around $50.00, and from Amazon. The heater is on the passenger side floor, and I of course make sure the area around it stays clear. After cogitating on various ways to run it's power cord out, I just opened up the rear door, ran the flat cord out an inch, and closed the door, done. The same way, and same door, I run the power cord out for when charging my e bike while driving, the rubber door seal is compliant enough to not hurt the cord, and both cords are flat, so KISS applies here.

    After the last few mornings of use, in 18 to 21 degree overnight temps, I have settled on the following: I click the remote on an hour to 2 hours before I expect to leave. A 15 watt bulb is my witness light, slaved to the same outlet the heater is on, so I can just look out and see it's on. Sometimes it takes 2 clicks of the remote, as I am at the outer range of the remote, so the light is just a visual backup. I always charge the PIP as soon as I park, and I leave the charger in place, it's right next to the heater plug, and since I can't drive off without first removing the charger (thank you for that Toyota engineers) and so far I have not failed to unplug the heater as I unplug the car. IF I do, the cord will just unplug, so no biggie. At first I used the 750 watt setting, but found, no surprise, the 1500 watts of heat was better. 1 hour brought the inside cabin temps up to 59-60, but 2 hours brings it up to a very cozy 69-70. Since I have free electricity via a large, in excess of what is needed, solar system, I don't care about the small power consumption.

    I didn't have any doubt's I could pre heat the cabin, but what has surprised me is how long the now heat soaked cabin remains warm, even making my 1200' descent at 45 mph in 18 degree temps. The cabin temp will drop to about 60, but by then I'm getting up to speed and on level ground, so the ICE motor takes over. I wish I had done this earlier, 3 years ago, having free electricity and NOT doing so was stupid! I seriously considered building a heated garage, or making major mods on the simple pole building so I could heat it, both ideas had major drawbacks, besides the expense. I should mention that the remote is key, in my area it is common to find 2-4' deep snow drifts, and having to suit up just to run out and turn on the heater manually would be more trouble then it's worth. I also bought a second remote, so my Kubota tractor block heater can be remoted without first having to go outside. With how little fuel a Prius uses, it is amazing how well it heats up, so I am not complaining a bit about the stock heater! My 1 ton pickup on the other hand, is throwing off good cabin heat in the first few minutes, one advantage to getting 15 mpg I guess.
     
  2. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    I gather you start out with the engine running? This seems the best (only?) strategy that is effective for using block heater on a plug-in.
     
  3. spudnut

    spudnut Active Member

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    I don't have any choice do I? I'll creep out of my driveway and gently accelerate up to 30, then once I turn downhill it may or may not start the ICE, but for sure, and with a fully charged battery, once I get on the level it wants, needs (to warm up the ICE anyway) to start. I haven't really noticed if the block heater has changed that scenario, and that's OK, I got it mostly for quicker cabin heat. Now the coolant is 80+ degrees on initial startup, much warmer then the 17 air temp this AM

    I should mention, I don't use a timer for my cabin heat, as my departure times are erratic, not 9-5, or even close to it.
     
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  4. Majafamily

    Majafamily Member

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    No suggestion but maybe seat warmers, if you have them, would help you stay warm too. Wouldn't help anyone in the backseat however. I know some shops will install aftermarket for 300-400 bucks in california.
     
  5. spudnut

    spudnut Active Member

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    I have seat warmers, came stock that way, my first car ever with them. But having the entire car heat soaked is on a whole different level, comfort wise. The seat warmers are great, and I use them often, another tool as it were, the more the better.
     
  6. sam spade 2

    sam spade 2 Senior Member

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    I think you are making this MUCH more difficult than it needs to be.

    One of those heaters that looks like a radiator likely would be MUCH better for your purpose because the liquid inside would retain the heat longer. They are fairly large so might have to be put on the rear floor.
    Also because of the design, even highly flammable things in contact with the heater are not likely to ignite.

    It is possible that a thermostat setting could be found that would keep it fairly warm for departure any time without using a lot of power.
    But in your case, the amount of power used doesn't seem important.
     
  7. BZzap!

    BZzap! Senior Member

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    Perhaps on initial departure you might consider keeping the car in “Brake Mode”. This will allow the ICE to run uninterrupted during your 1200’ egress from the property. Thus, getting the engine to operating temperature much sooner. In your case, evidently, every little bit of heat is going to help. BTW, be very careful of that unattended, ceramic heater in a plastic car!
     
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  8. Grit

    Grit Senior Member

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    Great idea, safe and effective. Is your descend downhill all down? I was thinking adding lower grill block if there’s no uphill as your leaving home to restrict cold air going into the radiator while using an app to keep track of temps. I used to descend down on a road from a dam in 40F temps and coast down weekly. After 5 miles down, ICE was only 128F.
     
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  9. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    Just to put this in perspective...2 hours at 1500 watts is 3 kwh. This is about the same amount it takes to charge the PIP battery and drive 11-14 miles. I would think that an electric seat heater would use much less power and make it much more comfortable in a shorter amoiunt of time.

    Mike
     
  10. spudnut

    spudnut Active Member

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    I always block off the entire lower grill during the winter (clear zip tied lexan), and always hit the down hill in brake mode, but there is just too much cold air rushing by for that to help much, at least until I get on level ground.

    The ceramic heater is great due to it's compact size and LACK off mass to heat up, before it starts throwing off useful heat. If I burn my car down due to inattention, by putting something extremely flammable extremely close to it, and leaving the heater for hours, that's my bad. i probably should mention my front passenger has long been out, so there is a ton of room in that area, and the heater is secured to a piece of plywood to keep it upright, though it also has a tip switch, and is designed to be safe to use while on carpet. My work schedule can go from 2 or 3 days off, to having to leave in 30 minutes, so I wanted a brute force approach, lot's of heat and quick. Yesterday, I had a 45 minute notice I needed to run into town and do a crane job, 18 degrees that night, and it was about 9:00 AM. At 9:45 the car was 49 degrees, much better! It's just a real nice way to make going to work on a cold nice person winter morning a lot more pleasant.

    The power usage does not matter a whit, seriously. I produce 5 KW an hour. I'd much rather use my free juice then a drop of gasoline.
     
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  11. vvillovv

    vvillovv Senior Member

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    Like 4th of July in Winter. Throw the Parka on the coat rack in the boot.. No snow on windows to brush off either.

    I swear, I think it actually allows the pack to hold more juice, even if that's not very noticeable with our smaller pack, both PiP and Prime.

    Inefficient - yeah sure is,,, Almost like havin to run the ice for free heat.
    And if it takes 3 or 4 hours driving dark country back roads EV / no HAVC to use all the charge in the Prime single digits ambient, everything is ICE cold at the end anyways. Can feel every tiny draft though the firewall. By the end all the windows are open, unless the driver breaths into the Dune survival suit.
     
    #11 vvillovv, Dec 5, 2020
    Last edited: Dec 5, 2020
  12. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    How about insulated/heated garage? Just a thought, for those that have one. One downside: if you're driving daily, in wet and salted road conditions, then it's prudent to park outside, avoids accelerated rusting.
     
    #12 Mendel Leisk, Dec 5, 2020
    Last edited: Dec 5, 2020
  13. Grit

    Grit Senior Member

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    o_Oo_Oo_Oo_Oo_O
     
  14. ChapmanF

    ChapmanF Senior Member

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    Just a note from the getting-the-units-right department, kW is already energy over time. If you have a system that puts out 5 kW and does that for a solid hour, it will have produced 5 kWh (extra h on the end).

    If a system can give you 5 kWh of energy every hour, "five kilowatt-hours an hour", the "hour" in two places will cancel, and that's just the same as saying it is giving you 5 kW. There is no "an hour" left over.
     
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  15. spudnut

    spudnut Active Member

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    The big surprise, was how long the benefits of cabin pre heating
    I have a 40 x 40 heated shop, but it's my SHOP, my second home! I don't want to open its 19' wide x 14' high door up twice a day just get the Prius in and out. Plus it would leave a large amount of slush, gravel, and road salt every time it all melts off, as in a 5 gallon buckets worth or so. I prefer to keep my daily driver in the pole barn, as it's a BARN, and as long it's out of the snow and frost, I'm happy. I gave serious though to building a separate insulated garage, I was a builder for most of my working life so no big deal there, but really didn't want to deal with the permit BS, and the current high cost of building materials, then the annual increase in my property tax. Plus the way my property, even though it's 40 acres, is laid out, there was no handy place for adding on an attached garage. It's an old rural tradition also....my pole barn is separate from the house, the shop separate from the barn and the house, the idea being you may not lose all your buildings if a fire starts in one, as no way the county fire department can offer more then "hosing down the embers" protection due to my location, this has been shown in other fires, by the time they get up the mountain it's over!

    The pole barn is also used for my tractor implements and other equipment storage, and installing any meaningful insulation would have been expensive, awkward (studs on 4' center) and really limit it's current function, plus I'd still have to heat it. The little ceramic heater was a cheap, simple, and effective solution, I now look forward to leaving on a cold morning!
     
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