We live in Vermont. Current temps. 40F-60F. We just got our M3 and are wondering how much power we can expect to loose % wise while sitting overnight in 40% temps.
Thanks
Thanks
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Amount of Power loss overnight
- Thread starter alset92977
- Start date
Around 1% with little temperature variation. However, if sentry mode is on it will drain much more. Also, I experienced more range loss while connected to WiFi but after owning it for a while I stopped bothering about it, so don't know if that's right or not
TimothyHW3
Active Member
If you do everything right and do not put up useless apps like TeslaFi or stats on the phone you can expect close to no loss over days.
I have a few videos where I explain this and a new one comping up where I tested it over 65 hours and the loss was 2km of range or about 0.5% over close to 3 days.
So the normal "loss" is around 0.1% per day or about 75 Wh per Day or about 3-5Watt consumption - that is the same as your standby on your PC or TV.
To achieve such results follow my setup here
https://www.youtube.com/watch?v=3JqLIGOnV0c
In the winter the loss is the same + the amount tesla blocks because the battery is cold. But this amount is not "lost", it is just blocked and when the car warms up it will be returned.
If you drive short distances at low speeds then it will not have enough time to warm up and your range in the winter will suffer. It all depends on your setup.
Here in this video I show exactly how the battery returns some of the loss. At the end of the video you can also see that once the temprature got back above 10C or 50F I gained back about 10 miles.
As long as the difference between the day temperature (when you park) to the overnight temperature is not a big difference, the actual drain should be low, <1%. If it's 50 when you leave it and then 20 at night, you'll notice it suddenly lost a lot of charge, that's just the battery getting cold and losing charge, not real lost of charge.
AlanSubie4Life
Efficiency Obsessed Member
First, disable all third party apps as has been mentioned. Unless you want them. Even if they say they have no effect they will.
Unlike some have said, it isn’t “virtually zero.”
These days, setting aside cooling effects (already mentioned above, they can reduce miles by 5-10 miles or perhaps more with a very cold battery, but temporary), a car that is sleeping properly (that means going 24-48 hours between wake ups) will lose about 1 rated mile per day. How?
It’s about 230Wh per day. When the car is sleeping, it consumes about 5W. When awake (idle), it consumes 200-250W. These are ballpark numbers but are close.
So, what happens is the car consumes ~5W for 24-48 hours, drawing 100-200Wh or so from the 12V. Then it wakes up, to charge the 12V, when the voltage drops to around 12.8V from ~13.5V.
The wake up has overhead (100W) in addition to the energy used to charge the 12V. It takes about 2 hours to charge the 12V after a 45-hour drain.
So when all is said and done, it works out to about 230Wh/day, assuming good solid sleep with no wake ups. That is one rated mile per day (a little more or a little less depending on the specific vehicle since different Model 3s have different rated mile energy content).
You can get a 12V battery monitor to be sure your car is sleeping well. If you want.
This is what it should look like.
If the car is waking up more frequently, for whatever reason, your daily loss will be correspondingly higher (that 100W overhead really adds up!).
TimothyHW3
Active Member
Yeah, I would say 5W is "virtually" zero, your TV will use more in idle or your lamp...
Anyways, not sure why you felt that you have to "re-summarize" what I said above and add "commentary"...
AlanSubie4Life
Efficiency Obsessed Member
Due to the idle mode overhead, the average draw is about 10W. (230Wh per 24 hours). Again, these numbers are approximate (within about 20%, based on my measurement interval).
It's interesting that your results are considerably lower than what I have observed. You do have to be careful about a test over 65 hours, because if you pick the endpoints incorrectly (you miss a recharge cycle, which is quite possible with this extremely short interval - you need to pick a time period which captures an integer multiple of recharge cycles, without extra end charges or extra long periods of discharge at the end of the interval, which bias the result), you can end up with an optimistic result. You can get the 12V monitor to make sure your test situation is valid (basically just make sure you are capturing the correct number of 12V recharge cycles in your interval and not artificially hurting or helping the result -there should be an equal number of charge and discharge cycles in the chosen interval, and they should all be complete).
In any case, I saw 4 rated miles lost over 96 hours in a recent test with optimal sleeping (just ~4 hours of charging in that interval). I was careful to have the car sitting (unplugged) for a few days before I began logging the data (otherwise variations in pack temperature and/or balance, unrelated to vampire drain, can affect the result - it is tricky!).
It's a tricky measurement to do correctly. It's better to do an interval of 10-20 days and estimate from that (much better precision on the rated miles, and less error due to a partial cycle capture), but obviously those opportunities are rare. But having the 12V monitor allows you to track exactly what happened if you do get that opportunity. (The 12V monitor consumes ~12mW, BTW.). There is not really another method, since you cannot use apps to monitor the sleep/idle behavior, without affecting the results.
This also implies that a 12V monitor may be able to warn you of impending 12V failure (the discharge phase may shorten), and a failing 12V MAY show up as higher vampire drain (though it would be difficult to detect). That’s why I have the monitor. Now that I have a baseline, I can quickly check for any unexpected changes in the cadence, before making any trip.
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TimothyHW3
Active Member
I turn off the car alarm (cabin heat protection also off) and actively turn off wifi before leaving the car, maybe that is the difference.
AlanSubie4Life
Efficiency Obsessed Member
Maybe. I have cabin overheat protection off. I was looking for typical configuration result without doing anything special. I could try disabling WiFi and see whether it slows the battery decay (would be easy to see). But I would suggest for your measurements doing a longer interval, if you are not able to monitor the 12V. You may have only captured one 2 hour idle cycle in ~65 hours. (Could have had 45 hours of sleep, followed by 2 hours idle, followed by 18 hours of sleep). That would give you just ~450Wh of consumption in that interval, which would be just 3 rated kilometers, which is close to what you saw (and due to rounding error and the other errors mentioned, it would be easy to see just 2 rated km).
My point is that 2 rated km over 65 hours does not imply 0.74km per day when measured over such a short interval. You have very wide error bars on that measurement, if you cannot control the error. I’m also not saying that your measurement is incorrect - we just don’t know.
In the end, though, as long as you aren’t running any apps, the loss can be quite low. It seems that it may have improved somewhat over the last couple years.
TimothyHW3
Active Member
Do you have car alarm and wifi off? I noticed that when I leave them on , especially car alarm the drain is double. Test it with them off for reference
AlanSubie4Life
Efficiency Obsessed Member
I tried this overnight (no wifi, no car alarm, no COH protection) and if anything the drain is slightly faster. I'll leave it for a bit longer to see what happens I guess. A little difficult to compare over short intervals, since there is some randomness to the rate of drain.
TimothyHW3
Active Member
Yeah, short intervals is not good especially when the battery has cooled off and at the colder temperatures we have now. You should try it in the summer or in warm garage.
AlanSubie4Life
Efficiency Obsessed Member
Lol. I live in San Diego; it was 80 degrees in my south-facing garage yesterday. Nice and cool compared to the high 80s outside.
AlanSubie4Life
Efficiency Obsessed Member
Could be Sentry, Summon Standby. Anything that prevents the car from sleeping (though 6% overnight is a bit high).
But if it's not those things, it can also be BMS adjustment to the actual SOC (not an actual loss).
