OK, so here's an example. I woke up to 40 degree weather. Car was parked outside not in a garage. It showed 196 mile range. I didn't pre-heat it at all. Drove about 3 miles. Parked it at home. About another hour later drove it about 10 miles. Actual driving miles to the 10th was 12.3. My APP is showing 174 mile range as we speak. That's insane. Can someone explain? I had that piece of %@%@% BMW i3 when it 1st came out that was a DISASTER - 32-33 miles on a full charge. But I wasn't expecting Tesla to disappoint. Other notes, I'm not gunning the car. And yes, I've only charged it a couple times, all at a Super Charger bc I don't have access to home charging at this point. Please advise. Thanks.
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Idling
- Thread starter DSMLVNV
- Start date
That Video only shows Heat & Seat at 20 amps. And then showed Seat Only at 2 Amps.
So it was 18 Amps for Heater only.
Also from Wall Power through Inverter into Battery and Out is not 100% efficient. Rule of Thumb is 80%.
So 80% * 18 Amps is now down to 14.4A amps that actually reach the heaters.
So with that data you are down to 3400 watts.
I don't know how much the fan uses and possible other systems at play. But I have a reliable source that says there are two 1000 watt heaters.
And back to the OP question I doubt he had heat full blast, while idle for 30 minutes. Probably 1000 watts at most once stable.
While driving I see heat can take as little as 20 wh/mi up to 100 wh/mi at say 60 mph for easy math.
While not moving you are gonna use a lot less heat. So at 1 mile per minute lets call it 30 wh/minute 30*30 is 900wh round that to 1kwh
That's 2% of battery which is about 6 miles range.
That is such a small data point to judge anything.
What was overnight temps?
Keep in mind as soon as you touch the door handle the car turns on cabin heat and the clock is running (i.e. battery is being consumed) until the car locks itself.
You are describing worst case. Were the 10 miles gaining elevation? What Speed were you driving? What tires? You probably had no regen, so stop and go traffic with no regen would be hard hit. Which car and tires do you run? How is your heat setup?
Some people are "behind the curve" even in warmer weather and then they give a bunch "poor" numbers and blame it all on the cold weather.
Just getting in a cold car and get up and going and shutdown twice probably cost you ~8 miles off the top.
dhrivnak
Active Member
Yes as you are using the HVAC. But unless it is real cold only a couple of miles (2-6) an hour.
I had a look and there is nothing about wattage. I assume you mean there is one heater core.
I said there are two 1000 watt heaters. I didn't say anything about where they are located.
That Heater core does say "Dual Zone" (i.e. Two Heaters).
AlanSubie4Life
Efficiency Obsessed Member
Guys,
Rather than debate, this is not hard to determine for yourself, with reasonable accuracy, if you have a wall connector or even a UMC (you just will probably max out the UMC - and I think even the wall connector based on data from others):
On a cool day, but with a freshly driven battery that doesn’t need warming, with cabin interior cooled to 62 or so (use the AC!)
Plug in car.
Make sure fan speed is maxed out.
Set charge limit below current charge level.
Crack one door slightly so the screen stays on. Make sure the charging page is up for your perusal. Make sure UMC/wall connector clicks on and provides current.
Crank the heat to max using the app from outside the car.
See the peakV*A on the screen. It’ll ramp up very high (I see 32/32A from the UMC when cranking heat). I suspect you will see that the heater draw can exceed 10kW, temporarily (I see it can go as high as 7kW). Since the battery is warm for this test scenario, it’s probably reasonable to rule out battery heating as a contributor.
Of course it will drop substantially as it comes to temp (another piece of evidence that suggests battery heat is not a factor).
The baseline load is about 2A at 240V, so subtract that from the peak number... you can determine baseline load by just turning off the heat in the app. I see about 2A. If I turn on all 5 seat heaters I see 4A. So seat heaters are about 500W total.
Turn on and off the heat and also turn on AC on max if you want and cool down the cabin (you’ll find it is more efficient by about 2-3x but check for yourself)
And you can then multiply by 0.9 or 0.95 or whatever you assume the charger AC->DC conversion efficiency to be.
I’ve posted elsewhere with experiments showing the heat power use plateaus down at about 1-2kW steady state when warming cabin to 70 degrees in the shade with a 60 degree ambient.
To answer the OP’s @DSMLVNV post, absolutely you can see significant mileage loss by prewarming the car or sitting idle (especially with climate on)! With a 1kW steady state draw, you’ll lose about 1 rated mile every 15 minutes. If it is 40 outside with no solar heating you’ll probably see more than that.
This is one major reason why winter kills the efficiency...heat takes a lot of power!
Seat heaters ~100W each at Max
Heat+Fan: at least 7kW peak
Baseline load in idle with screen on: ~500W (this may include other loads that aren’t there when driving but I have no way to know)
These numbers can be reduced by the charger efficiency as mentioned above.
Rather than debate, this is not hard to determine for yourself, with reasonable accuracy, if you have a wall connector or even a UMC (you just will probably max out the UMC - and I think even the wall connector based on data from others):
On a cool day, but with a freshly driven battery that doesn’t need warming, with cabin interior cooled to 62 or so (use the AC!)
Plug in car.
Make sure fan speed is maxed out.
Set charge limit below current charge level.
Crack one door slightly so the screen stays on. Make sure the charging page is up for your perusal. Make sure UMC/wall connector clicks on and provides current.
Crank the heat to max using the app from outside the car.
See the peakV*A on the screen. It’ll ramp up very high (I see 32/32A from the UMC when cranking heat). I suspect you will see that the heater draw can exceed 10kW, temporarily (I see it can go as high as 7kW). Since the battery is warm for this test scenario, it’s probably reasonable to rule out battery heating as a contributor.
Of course it will drop substantially as it comes to temp (another piece of evidence that suggests battery heat is not a factor).
The baseline load is about 2A at 240V, so subtract that from the peak number... you can determine baseline load by just turning off the heat in the app. I see about 2A. If I turn on all 5 seat heaters I see 4A. So seat heaters are about 500W total.
Turn on and off the heat and also turn on AC on max if you want and cool down the cabin (you’ll find it is more efficient by about 2-3x but check for yourself)
And you can then multiply by 0.9 or 0.95 or whatever you assume the charger AC->DC conversion efficiency to be.
I’ve posted elsewhere with experiments showing the heat power use plateaus down at about 1-2kW steady state when warming cabin to 70 degrees in the shade with a 60 degree ambient.
To answer the OP’s @DSMLVNV post, absolutely you can see significant mileage loss by prewarming the car or sitting idle (especially with climate on)! With a 1kW steady state draw, you’ll lose about 1 rated mile every 15 minutes. If it is 40 outside with no solar heating you’ll probably see more than that.
This is one major reason why winter kills the efficiency...heat takes a lot of power!
Seat heaters ~100W each at Max
Heat+Fan: at least 7kW peak
Baseline load in idle with screen on: ~500W (this may include other loads that aren’t there when driving but I have no way to know)
These numbers can be reduced by the charger efficiency as mentioned above.
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So the other day I put a power meter on the line at my breaker panel and when I turned on the heat to max through the app it maxed out the power draw for the circuit at 24A/238V. And that was without the seat heaters on, and the car was fully warm from an hour drive. So that is definitely more than 2kW no matter how you slice it. Dual Zone doesn't explicitly mean dual climate systems...would it have dual A/C's then as well?
AlanSubie4Life
Efficiency Obsessed Member
@eprosenx has posted his data.
Shore power usage during morning warmup
It does appear that the heat use could approach 10kW. Since I just have a UMC right now all I can say is it is at least 7kW.
All these numbers can be reduced by the efficiency of the charger - but I suspect that is at least 90-95% efficient - 80% would be too low. (The charger efficiency impacts MPGe so there is an incentive to make it very efficient.) I haven’t had occasion to try to measure this charger efficiency yet - if someone has, they should just give us the efficiency at max load. I am sure it is posted elsewhere in these forums...
Dual core means two co
And don't forget to meter the pack to know it is also not being drawn on besides the mains....
AlanSubie4Life
Efficiency Obsessed Member
Yes. That's the reason to use the wall connector. It's reasonable to assume that we can only establish a lower limit to the wattage the heater/fan/etc. can draw, with this method. The higher the connection power available, the easier it is to determine the peak.
I'm actually not sure exactly how this works, schematic wise...in order for the charger to be providing current for these accessories, but not charging the battery, the voltage has to be exactly correct if the contactors are closed. I didn't hear them clunk open as I recall (pretty sure they are always closed in parked mode, at least after a few seconds). I guess the charger can just monitor & apply the exact correct voltage to the battery so there is no net current flow to it (but other accessories will still draw current). But not sure how exactly it all works.
AlanSubie4Life
Efficiency Obsessed Member
If you have access to this, feel free to do it and fill us in. I'm satisfied that the proposed method gives a good lower estimate for someone who doesn't have access to the API (assuming it is available there - anything significant would show up in the rated miles change anyway (we have about 250Wh resolution), and you could reduce error due to that, with a longer heating experiment with doors wide open, and include any change in the rated miles during the experiment in the calculation - it's not complicated!). The point is that the usage for the heating is potentially extremely high, which is what the OP was unaware of.
Of course you could just directly look at miles lost per time to eliminate charger inefficiencies, for an integrated measure of energy use when disconnected from the power source, but it provides less visibility of variation in the amperage draw with time. Unfortunately Tesla doesn't provide a kW meter on the dash like GM does in the Chevy Spark, etc. - EXCEPT when it is plugged into the power source.
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AlanSubie4Life
Efficiency Obsessed Member
At least we know its two 1kW heaters now
Ha. Yeah, pretty sure there would be some big complaints from Tesla owners about cold cabins, if that were true! Spark EV cabin heater can draw 7-8kW, so...
You don't need windows open. Just put temp on HIGH. It is not under thermostatic control on HIGH or LOW.
I admit that idle, no charging on shore power with it on HIGH it draws a lot of amps to account for 2000 watts. It's hard to prove where all the watts are exactly going and how the system operates when on shore power.
A more accurate way to measure would be to drive say ~5 miles or so, at a good medium temperature (e.g. 70F). Flat road with HEAT on HIGH and then HEAT on LOW and compare. If you drove the same road for the same speed, it should be close enough.
AlanSubie4Life
Efficiency Obsessed Member
Not sure I follow exactly what you are saying here. Anyway, for 2kW it would be 8.3A @ 240V (possibly as high as 9 or 10A accounting for charger losses). This is not very much current! That’s the reason the experiment makes it very clear that the (peak) heater consumption is much, much higher than that. Steady state of course that 2kW may be reasonable or even high in some conditions.
Your other method would be very accurate but would hide the dynamic nature of the draw. Good point on the max/min settings. Haven’t confirmed but it is possible the current may still be higher initially than the steady state “HIGH” setting since a PTC may draw more current initially due to its positive temperature coefficient. No idea really.
