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Winter Performance

Discussion in 'Roadster 2008-2012' started by Doug_G, Nov 27, 2010.

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  1. Doug_G

    Doug_G Lead Moderator

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    Cabin Heater Performance

    I made an interesting discovery last night. The heater power level depends not just on the heat/cool knob, but also on the fan speed. Here is my data:

    Heat off, Fan any - 1.0 amp average
    Heat full, Fan off - 1.0 amp average
    Heat full, Fan 1 - 3.0 amp average
    Heat full, Fan 2 - 6.8 amp average
    Heat full, Fan full - 9.5 amp average

    So if you're feeling cold in the cabin, you need to crank the fan all the way up.
     
  2. vfx

    vfx Well-Known Member

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    Makes sense. You can;t have the coils just getting hot. They have to have a fan to keep the temp down. But I find if you put the fan to high then you get cold air blowing until the coil heats up.
     
  3. cinergi

    cinergi Active Member

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    When it's really cold, I notice than heat full, fan 2 is 8-9 amps until it warms up and it'll drop down to 7 amps. At that point, I sometimes run the fan at 3, but that tends to dilute the air too much for my liking until the cabin is warm enough to support it (via recirc).
     
  4. Doug_G

    Doug_G Lead Moderator

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    Well, yes, they need some air flow to prevent the heater from getting too hot. But there are several problems with this:

    1. Fan on medium is plenty to keep the heater from overheating.

    2. Fan on high is very noisy. Lowering the fan to medium transfers just as much heat, and the heat out of the vents is actually warmer. You're just drawing in too much cold air if it's on full (in winter conditions you can't put it on recirculate or the inside of the car will frost over).

    3. During the time that the air is still cold, before the heater warms up, you need to set the fan to low and put it on the windshield. Otherwise your breath will fog over the windscreen. But if you put it on high while the air is still cold you risk a flash fog-over, which is dangerous.
     
  5. Alan

    Alan Member

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    Agree with comments above - fan on medium with air on recycle seems a good compromise.

    Like many I have the cold feet issue so have messed around with the vents to get more air to the drivers side (RHD car) which has improved things. Has anyone played around with improving the thermal insulation in the footwell. Perhaps more carpet or some insulating foam under the existing carpets.
     
  6. cinergi

    cinergi Active Member

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    So here's a kicker on range. It was 55-60F here Thursday and Friday ... And my EM SURPASSED my IM purely on my daily commute (some hills but net-zero elevation change). I was reading 185 EM with 175 IM. When it was really cold, my EM was 110 at most. My whpm 30-mile avg was very low 200's vs. 300-370. I used well more than 25% when very cold vs. Well less than 25% (I'll try to get accurate SOC numbers from the logs later).
    My average speed is probably less than 30 (I should set up a trip and actually measure it, but I know it takes 30-35 minutes to go 16 miles). Thinking about that ... It means I'm using 3kW over 30 minutes or 1500 watt-hours ... Over 16 miles that's 94 whpm to Heat the cabin on high, which is in line with the increases I saw on my whpm graph... That's not even including what I lost with regen disabled for the return trip home... (I should also measure that). So off the highway (some stop and go, 30 MPH average) traveling in the cold is nearly 50% more energy (33% less range). Am I missing something (check my math)?
     
  7. mpt

    mpt Electrics are back

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  8. Doug_G

    Doug_G Lead Moderator

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    I avoid air recirculation like the plague, unless the A/C is on. Here in Ottawa it's so humid most of the time you'll fog up in minutes with the recirc on. This is true for any car, not just Roadster.
     
  9. Brian H

    Brian H Banned

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    #209 Brian H, Mar 29, 2011
    Last edited: Mar 29, 2011
    Some people have mentioned that blocking the passenger-side footwell vent works fine for cold feet. Doesn't freeze the passenger, just seems to cut total airflow enough to produce fully heated air, I'd guess.

    Also, the 30W floor/seat heated pads available placed appropriately seem to do the job. Forget the brand name ...
     
  10. mpt

    mpt Electrics are back

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    Yes, here: Living with a Tesla Roadster

    What happens is that the normal configuration results in 80% of the warm air going to the passenger & 20% wafts over to the driver. This patch diverts 100% of the air diagonally across towards the driver resulting in more like a 50/50 split of the warmth. I used that metal duct tape and it's stuck ok for more than a year now.
     
  11. zack

    zack Member

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    Someone posted on the forum somewhere about insulation that can be cut and fitted under the carpet. It seemed like excellent stuff, multi-layered with both acoustic and thermal properties. Does anyone know where that post is? I've used the search function to no avail.
     
  12. Eberhard

    Eberhard #421 Model S #S32

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    That won't help. the problem is the air from outside. first: you can only prevent the cold air to come from outside by setting to internal circulation and setting to upstream. second: wrap your feet in a heating mat. third: engage the electric heater and block the outlet to the passenger-side.
     
  13. Doug_G

    Doug_G Lead Moderator

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    That's a non-starter around here. Too much humidity. The car windshield would frost over within minutes - sometimes even seconds.
     
  14. Eberhard

    Eberhard #421 Model S #S32

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    then choose #2 or #3
     
  15. zack

    zack Member

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    If anyone knows where that information was posted, please let me know.
     
  16. TEG

    TEG Teslafanatic

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  17. TEG

    TEG Teslafanatic

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  18. zack

    zack Member

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    Ahh, I found it! More summertime mods to be made to the car in preparation for cold weather driving.

    Jay Leno's garage... Dynamat!

    The guy from the company says "first dynamat extreme on everything. Then dynaliner, 1/8" on sides, 1/4" to 1/2" on the floor, and 1/2" on the firewall. Not that there's a firewall in the Tesla, but more insulation is better in my book, when it comes to air leaks and cold aluminum!
     
  19. Eberhard

    Eberhard #421 Model S #S32

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    Pure insulation doesn't work. You need active heating.
     
  20. cinergi

    cinergi Active Member

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    Indeed I just experienced #1 for the first time this past weekend. When it's 100% full, there's basically NO regen. As you get closer to 90% SOC, it gradually increases in strength (all while the NO REGEN light is on) and at some point, it snaps to full strength. The g-force curve isn't great when in this mode ... e.g. when approaching a toll in this mode, there was almost no braking forces at 40 MPH so I'm using the brakes ... and as I approach 20 MPH, the effect of regen really starts to kick in so it gets difficult to control how quickly I'm braking. The regen seems to be capped at a KW number and thus as you approach slower speeds, more braking force is required to stay at that capped number. (You can see this effect with normal regen on the highway ... lift off the pedal at 80 MPH and you'll stay at ~35 KW for a while .. and as your speed lowers, the braking g-forces increase)
     

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