Vampire drain 0.5% per day is not bad

[SilentWarp]

Things may be improving compared to what I have heard (?). Had it parked for 2 days, went from 84% to 83% in 'Last Seen 2 days ago...' refresh. Not a great sample size for just 43 hours, but I'll be parked for 5 days while I travel this weekend in wife's car. I'll see how it drops from 100% to see if this is for real.

(LFP, May '23 build, garaged, 90F/75F ambient, 2K mi obo)

 

[GtiMart]

That looks normal. At that level you can't even tell if the energy was really spent (e.g. drain) or if it's simply bms readjustment.

 

[SilentWarp]

That looks normal. At that level you can't even tell if the energy was really spent (e.g. drain) or if it's simply bms readjustment.

Are you saying that LFPs normally leak 0.5% a day, or that there is no way to accurately measure leakage with LFP?

 

[3sr+buyer]

0.5% per day is about 300 Wh per day on a 60 kWh battery. This seems to be about 12.5 W (over 24 hours), which seems ordinary for a Tesla Model 3 that is turned off (i.e. nothing keeping it on like Sentry Mode, Cabin Overheat Protection, frequent checking with the Tesla or third party apps, etc.).

 

[GtiMart]

I'm saying that 1% is the minimum variation in the measure that you observe, and that it could be because of a bms readjustment and not necessarily because of consumption. The numbers are too small to draw precise conclusions is what I'm really saying.

With that said, I expect in the range of 20w of continuous draw on a model 3 or Y when it is sleeping. For 2 days that would be close to 1kWh so ~1.5% SOC on an LFP. That is in fact pretty good. Contrast that to 200-250w consumption when the car is awake...

 

[AlanSubie4Life]

Are you saying that LFPs normally leak 0.5% a day, or that there is no way to accurately measure leakage with LFP?

To measure accurately, you have to let the car sleep and readjust the BMS first. Then start your measurement from that point (using rated km, not %!), not from the time you parked the car, over a period of several days.

 

[SilentWarp]

To measure accurately, you have to let the car sleep and readjust the BMS first. Then start your measurement from that point (using rated km, not %!), not from the time you parked the car, over a period of several days.

I'll try that before my next trip, but why would I care about rated miles, when that is relative (to my driving) -- Battery SOC is not.

 

[GtiMart]

"rated" miles are not related to your driving. The display on the main screen reports battery capacity (kWh) divided by the consumption constant as the EPA test for your car to come up with rated, or EPA miles. Rated miles is just a (rough) proxy for kWh, when you know that constant.
EDIT: It's also a more granular measure, more precise than percents.

What is adjusted to your driving is the information in the energy graph "app".

 

[AlanSubie4Life]

but why would I care about rated miles, when that is relative (to my driving) -- Battery SOC is not.

As @GtiMart said…

SOC % actually does not have fixed units since each % is just a portion of your overall battery capacity, which is variable (trends down).

But aside from that, km has the best resolution. For a typical Model 3 it’s around 118Wh/km (SR+ 263miles, 52.5kWh) to 152Wh/km (Perf 315mi, 80.6kWh).

For yours it is 132Wh/km. That is the resolution.

While % is around (when new) 577Wh/%. (60.5kWh pack)

So if you want to measure the most accurately you wait for the BMS to adjust first, and use kilometers which are fixed energy units independent of driving.

In the new vehicles (lithium 16V “12V” battery) the vampire is allegedly extremely low (as it should be, since the car should use essentially zero energy (substantially less than 1W) when parked with no features in use). Not saying it does, but it always should have. And new cars are alleged to be around this level.

Doesn’t take any energy (in this context) at all to run Bluetooth. And there is nothing else for the car to do really except monitor the battery, which of course should be even lower power.

 

[3sr+buyer]

In the new vehicles the vampire is allegedly extremely low (as it should be, since the car should use essentially zero energy (substantially less than 1W) when parked with no features in use). Not saying it does, but it always should have. And new cars are alleged to be around this level.

How new, and how much did the older ones use?

But also note that opening a door or something like that turns the car on for a short time, so if that is occurring, then the consumption will be greater than if just parked.

 

[AlanSubie4Life]

But also note that opening a door or something like that turns the car on for a short time, so if that is occurring, then the consumption will be greater than if just parked.

Of course, but that's not included in vampire drain (since that's a "feature" or just "use"). Typically vampire drain is only important (very important - must remember to turn off Sentry Mode!) when in remote areas and in those cases the car would typically not be touched until it is time to use it again.

How new, and how much did the older ones use?

I provided some clarification before your post but after your quote. The ones with lithium "12V" are alleged to be better. I think any changes to sleep power design must be associated with this change (since the sleep power directly impacts the amount of thrashing on the "12V" battery).

The old ones seem to be around 6-7W or so. Just totally hammers the 12V lead acid.

I expect in the range of 20w of continuous draw on a model 3 or Y when it is sleeping.

This is too high, even for the older models. It's around 6-7W on older vehicles (this has been measured, not by me (by @rrolsbe ) , and it's pretty consistent with what I've seen when leaving my car for several days). This is still very high but makes the vehicle usable for remote locations with reasonable length trips. (The average including mandatory wakeup to recharge 12V is a bit higher due to the wakeup period, and that will bring the average power closer to 10W, maybe.)

For new models it is alleged to be far better as mentioned.

 

[zoomer0056]

Yeah, I also have low vampire drain on a 2022 MSLR. If you want to monitor your car without waking it you can use the Tessie app.

 

[GtiMart]

Thanks @AlanSubie4Life . I've typically used 20-25w as a rough measure but that probably included 12v charging and possibly other wakeup events, a result of dividing a rough energy value by hours. I'm happy to know it's lower than I thought. I have an "older vehicle"