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Insulate the battery in cold weather?
- Thread starter billarnett
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- Driving Dynamics Model S
Jaff
Active Member
Agree...insulating might work out to be beneficial, but I think I'd wait until Tesla gives the idea it's blessing...not sure this is a good idea for the DIY'er as a tinkering project...
Not necessarily. There are a number of other reasons. In order of effect:
1. Fresh unpacked snow
2. Cabin heat
3. Tire pressure (air shrinks in cold weather, so compensation is necessary to avoid underinflation)
4. Standing water (effect varies with water depth)
5. Denser air (effect varies with speed)
Once the battery is up to temperature, it doesn't take much to keep it warm as just driving heats the battery. Getting it up from scratch (if you don't preheat) does take energy, but it's unlikely that any amount of insulation would make a practical difference if the car sits overnight in the cold.
46&2
Member
This is a fantastic idea, especially if the pack really has no insulation right now. It does cool very quickly.
Tesla also does not recommend externally heating the car from underneath... I was trying to figure a way to keep the pack a little warm without heating my entire garage.
I'd guess the insulation should be inside the titanium shield, if possible. Is the shield removable (I know it's installed after delivery)
-m
Tesla also does not recommend externally heating the car from underneath... I was trying to figure a way to keep the pack a little warm without heating my entire garage.
I'd guess the insulation should be inside the titanium shield, if possible. Is the shield removable (I know it's installed after delivery)
-m
Maybe I'm missing something.
As far as I know, all of the additional "tank mode" shielding is in front of the pack itself, and the only shield on the pack is the 1/4"? aluminum pan itself. I know Tesla made it thicker then it had to be to protect the pack, but I don't think there's additional armor on the pack. It seems like a fairly thin foam core with a hard lower surface could be easily attached to the bottom of the pack with no ill effects.
(Correct me if I'm wrong - that's just my recollection from the threads last year.)
Walter
About March 2014 there was an incident where road debris punctured the battery pack from beneath. So Telsa said they were installing a titanium shield on the underside to prevent it. I have not seens the shield or how it is installed but it could be helpful if it could hold the insulation on, perhaps.....
-m
-m
I wouldn't bet on anything as fancy as you're suggesting. I'm sure that Tesla's engineers monitored the temperatures away from the sensors with thermal cameras during testing, but aside from the drive motor rotor (where they can't measure directly,) I doubt that they used any algorithms from the sensors. My expectation from what I've seen in aerospace is that they just determined the places most likely to overheat and the ones that matter most, instrumented those, and then confirmed with the testing that they are the critical parts and there aren't unexpected hot spots.
They available data on power limiting suggests that the car is using a fixed lookup table for the rotor temperature with no adjustment for outside temperature or coolant temperature. I seriously doubt they are using something more sophisticated on parts of the battery they could directly measure if Tesla was worried about them.
I'm having trouble picturing the insulation actually being an issue. We know that Tesla has temperature monitors in every module, and that the modules themselves have some insulation from the case (the acrylic? shell that won't conduct heat well, though it presumably isn't designed as insulation.) Every cell has direct contact with the coolant, though - presumably far more heat is transferred into/out of the coolant than would ever go to the case.
Having said that, I have no access to Tesla's design documentation, and anything you do to your car is always your responsibility.
Walter
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You mean this one?:
http://www.edmunds.com/tesla/model-s/2013/long-term-road-test/2013-tesla-model-s-underbody-battery-shield-kit-installed.html
Like I said, the new bits are fairly small, and all installed in front of the pack (though the aluminum bash plate overlaps the forward few inches of the pack I believe...)
Walter
The shield just prevents debris from hitting the forward part of the pack (the square end). It doesn't cover the pack's bottom which is already armoured. The two pieces are really quite small. The problem (with a whole two incidents) was that the debris could be picked up in the space in front of the battery and then it could punch a hole in the battery. The two titanium skid plates keep the debris under the car so the pole vaulting effect can't happen.
> trying to figure a way to keep the pack a little warm without heating my entire garage. [invisik]
Commuter who has records of energy used daily to pre-heat MS before leaving home. Correlated by overnight min temp.
Commuter who has unheated fairly well sealed garage and ideally an air suspension.
Lower car onto old mattresses laid out on the garage floor as soon as you get home from your commute (before battery cools). Doesn't matter if they stick out past the rocker panels here and there, just try to cover most if not all of the battery bottom. Then change your automatic pre-heat to manual to avoid possibly overheating the battery next morning.
Next day apply manual pre-heat keeping eye on in/out temp with Visible Tesla. You should notice a big energy savings in getting the car up to normal exit temp.
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Commuter who has records of energy used daily to pre-heat MS before leaving home. Correlated by overnight min temp.
Commuter who has unheated fairly well sealed garage and ideally an air suspension.
Lower car onto old mattresses laid out on the garage floor as soon as you get home from your commute (before battery cools). Doesn't matter if they stick out past the rocker panels here and there, just try to cover most if not all of the battery bottom. Then change your automatic pre-heat to manual to avoid possibly overheating the battery next morning.
Next day apply manual pre-heat keeping eye on in/out temp with Visible Tesla. You should notice a big energy savings in getting the car up to normal exit temp.
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Because of reasons deonb stated, if I had a Tesla I'd be more tempted to spend my money on turning the garage into an air conditioned space (including heating) than muck with the car insulation so no ill effects happen to the car, unless Tesla specified a proper (supported) method to insulate the battery.
The reason I've been hoggish on converting the garage is that traditionally garages have been used to ventilate toxic chemicals, including automobile exhausts and oils. Now, though, the quantity of toxins emanating from the Tesla should be so much less that you can ventilate say, the exhaust of the house (except bath/kitchen/laundry (don't want moisture, filth, greases, toxins and smells from those)!) into the garage and let that ventilate to outside out a very small vent (in same direction of prevailing winds), and insulate the rest of the garage fully (idk, 3.2" composed of 2" insulation mats on your empty concrete garage floor covered with 1 1/8" plywood sheets with countersunk concrete anchors outside the range of the tires (perimeter except garage doors for cars) with floor-designed polyurethane adhesive in the field to avoid tire puncture, with a concrete or wood ramp someplace in your driveway (at least a dozen feet from garage) to get the car safely onto it, then insulate the garage door with some properly designed rubber slats to close out edges (remember to reset its floor height now that floor is raised), and insulate the rest of the garage structure (walls, roof) with normal household insulations, and bring in the treated air from the house to the garage (one way vent to avoid back flow, check fire codes too), or whatever works for you). Of course, you'd want to do this on a virgin garage that has never had a chance to absorb a lot of toxins into its structure (concrete, wood, etc.), or if you've lucked out and only ever had non-toxic use of the garage. Or you could get an expensive sealant (they are hard to source and expensive, but do exist -- I've seen them installed in toxic chemical rooms of high-rises, and are typically epoxies) to convert an old garage to "virgin enough".
The reason I've been hoggish on converting the garage is that traditionally garages have been used to ventilate toxic chemicals, including automobile exhausts and oils. Now, though, the quantity of toxins emanating from the Tesla should be so much less that you can ventilate say, the exhaust of the house (except bath/kitchen/laundry (don't want moisture, filth, greases, toxins and smells from those)!) into the garage and let that ventilate to outside out a very small vent (in same direction of prevailing winds), and insulate the rest of the garage fully (idk, 3.2" composed of 2" insulation mats on your empty concrete garage floor covered with 1 1/8" plywood sheets with countersunk concrete anchors outside the range of the tires (perimeter except garage doors for cars) with floor-designed polyurethane adhesive in the field to avoid tire puncture, with a concrete or wood ramp someplace in your driveway (at least a dozen feet from garage) to get the car safely onto it, then insulate the garage door with some properly designed rubber slats to close out edges (remember to reset its floor height now that floor is raised), and insulate the rest of the garage structure (walls, roof) with normal household insulations, and bring in the treated air from the house to the garage (one way vent to avoid back flow, check fire codes too), or whatever works for you). Of course, you'd want to do this on a virgin garage that has never had a chance to absorb a lot of toxins into its structure (concrete, wood, etc.), or if you've lucked out and only ever had non-toxic use of the garage. Or you could get an expensive sealant (they are hard to source and expensive, but do exist -- I've seen them installed in toxic chemical rooms of high-rises, and are typically epoxies) to convert an old garage to "virgin enough".
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Here's a description of the additional battery armor. The battery itself is actually protected by a new aluminum extrusion. The titanium plate protects delicate equipment in the frunk. There was lots of discussion and photos posted when this was first released.
Tesla Adds Titanium Underbody Shield and Aluminum Deflector Plates to Model S | Tesla Motors
In any case, this armor doesn't provide any significant thermal protection, and so can be ignored for the purposes of this thread.
I ordered 60 feet of 3M Dual Lock tape (turbo charged all weather velcro) to cover both my M3s' batteries with reflectix. Can't wait to try -30 eFfing degrees again. Last year it kicked my butt.
I'll report results in a week or two
I'll report results in a week or two
Same day, temperature (20°F), no wind, 60 MPH top speed enroute to and from shop. Non wrapped 358 Wh/mi, wrapped 309. Again, I drive a Model 3.
60 feet was not enough. Don't start this without 90 feet of 3M's SJ3550 Dual Lock or your preferred sticky stuff. Mine is holding, but until I get the rest of the dual lock installed I will be nervous driving faster than 70 MPH. Don't try it without a lift. I had a roll 4 ft wide. The 5 ft HVAC contractor stuff could cover it in one piece.
60 feet was not enough. Don't start this without 90 feet of 3M's SJ3550 Dual Lock or your preferred sticky stuff. Mine is holding, but until I get the rest of the dual lock installed I will be nervous driving faster than 70 MPH. Don't try it without a lift. I had a roll 4 ft wide. The 5 ft HVAC contractor stuff could cover it in one piece.
How long were those drives? I assume the unwrapped was first?
It’s really hard to draw useful conclusions here because the battery temperature is a central variable that’s not controlled or even monitored unless you dig into the car for diagnostic data.
I’ll be interested to see what your experience is like over the next several days.
That was installation day, 49 miles between home and brother-in-law's shop. I don't normally document this stuff but like anyone curious, I have watched the energy graph to learn how speed, heater and A/C, outside temperature, smooth vs. rough lane, and precipitation and snow pile effect energy efficiency. I think Tesla engineers could show me with data. But I mostly just drive and watch.
Reflectix might tear when running over frozen ruts. So I gotta be careful. Avoid anything that might harm the bumper cover I guess.
11/21 (bare battery pack) I used 151 miles of range driving 93 miles at 79 mph in 41° F.
12/3 (insulated battery) I used 121 miles of range to drive 93 miles at max 75 mph at 32°.
On that commute, +4 mph normally costs ~5 miles of range, while 9° colder normally costs ~15. Anecdotal, but I'm convinced that Reflectix not only helps, but is worth it.
So I might sell insulating kits. Buy bulk (for single sheet install) HVAC contractor 5' wide x 5/16" thick (instead of my 4' x 1/4" that Menards sells) rolls of reflectix and Dual Lock and sell pre-cut, taped when and as I learn the different layouts, battery insulating kits complete with instructions. In pre-taping, probably leave short gaps and/or just tape the main, lengthwise strips to allow folding for shipping.
Maybe I'll offer a battery wrap service and that way get the patterns for many different models and versions of EVs that I could then sell kits for.
Would any of you be interested if I could sell a battery blanket kit for $100?
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