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Battery drain during charging

Have an odd situation. My Y only seems to phantom drain battery when it’s plugged in. This has been happening for several weeks….I plug in (about once per week) and have it set to 85%. In the morning it‘s usually at 81 or 82%. I looked at TeslaFi this morning to see what was going on. I can see the car did get to full charge but then it just dropped thru the night (while still plugged in). The app also shows battery charge set to 85% and it shows level at 82%….but charger is not on. I moved the slider to 86 and then down to 85 and it turned on. Any ideas what could be happening here? I don’t have the best battery health overall….I think I have 12-13% off over the last 2 years, if that matters at all.

Thanks!
 

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OK, mine acts in the same manner, with preconditioning turned on. Yesterday, charged early to a limit of 65%, once reached car sat and it went down to 60% before turning back on to precondition for departure.
Interesting. Do you have drain when not plugged in? My car seems to hold charge very well when it’s just sitting in the garage. It’s like there’s phantom drain because it’s plugged in.
 
Interesting. Do you have drain when not plugged in? My car seems to hold charge very well when it’s just sitting in the garage. It’s like there’s phantom drain because it’s plugged in.
Not abnormal drain, just normal drain from Sentry or COP, but it was in the 50s yesterday when plugged in. Either way, I thought the car was suppose to stay at the limit and then use shore power to handle all auxiliaries.
 

DanDi58

Active Member
Jun 22, 2020
2,146
1,724
Dayton NJ
Have an odd situation. My Y only seems to phantom drain battery when it’s plugged in. This has been happening for several weeks….I plug in (about once per week) and have it set to 85%. In the morning it‘s usually at 81 or 82%. I looked at TeslaFi this morning to see what was going on. I can see the car did get to full charge but then it just dropped thru the night (while still plugged in). The app also shows battery charge set to 85% and it shows level at 82%….but charger is not on. I moved the slider to 86 and then down to 85 and it turned on. Any ideas what could be happening here? I don’t have the best battery health overall….I think I have 12-13% off over the last 2 years, if that matters at all.

Thanks!
It looks like you might using Scheduled Charging to start charging at a certain time? If that's the case, then any drain caused by the car's Sentry mode or COP will only use energy from the battery, not your home, if it's outside of that window. That is, once the car completes charging, it won't charge again until the set time.

Check to make sure you have Sentry mode disabled for your home, as that can be a big drain. If it's going off frequently, the car will never really go to sleep so is always using energy to keep it powered up.
 
That might have been me messing around this morning. Either way, the app pic shows the car set to 85 and the charge at 82. As to the other question, no temp change for me…I’m in south Florida. And I have sentry mode shut off at home. And I don’t use scheduled charging. Like I said , I don’t really see any drain when NOT plugged in.
 
If you are plugged in and the car's SOC goes under the target charging SOC without charging, this is not a "drain" problem, there's something else. If the battery really loses energy enough for the SOC to lower by 1% or more, the car will start charging again to reach the target SOC. If on the other hand the car changed its mind about the "available" energy in the pack, for example if the pack temperature lowers enough, it won't start charging because the energy is still present (but temporarily unavailable).
Verify if you really have a drain issue or if it's just varying reporting. I know you're in Florida but it's still unclear that your battery is really draining.
 
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Undecided_2

Member
Supporting Member
Jan 21, 2022
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Helensburgh
I had the same until I turned off sentry/cabin overheat and stopped opening the Tesla app. I use the widget on my phone and I can see it going to sleep as it’s ‘last seen’ time is shown. I also avoid taking my phone near it if I’m not going to use the car as Bluetooth would activate it/awake it.

I was losing ~4% within ablut 12/hours before I did this while on charge. Now I lose about 1% every two days which I think is very good.
 
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Ah, well that's a totally different topic, but yes keeping the car alive (either with sentry or opening the mobile app) means the car consumes ~200-250w constantly. That means 1kWh in 4-5 hours. That does not explain why the car wouldn't have started charging when its SOC is 82% and your target is set at 85%.
Also, the simple fact of having the car plugged shouldn't keep it awake. If that's the case, I've heard that a few times before, and from memory I think there was a problem with the charge port controller. Still, the car should have started charging again when its SOC goes under the target SOC.

So, which problem does the OP really have, so we look at the right one?
 
Same observation here, but on a smaller scale. I also charge about once a week to 85%. When I plug it in, I typically see a 1-2% drop after charging, but on days I don't charge, the drain is typically < 1% (0-3 miles). Maybe the charger being connected is losing electricity kinda like power lines lose electricity?
 
Yes, but no... :p Tesla decided to show AVAILABLE energy in the car, although the charging system uses the ACTUAL energy in the car. As said higher up, a difference in battery temperature can affect available energy but should not affect charging. It's unfortunate that many people end up taking some of the services centers time to get clarity on things that could be self-handled if we had more information from the car.
 

DanDi58

Active Member
Jun 22, 2020
2,146
1,724
Dayton NJ
Same observation here, but on a smaller scale. I also charge about once a week to 85%. When I plug it in, I typically see a 1-2% drop after charging, but on days I don't charge, the drain is typically < 1% (0-3 miles). Maybe the charger being connected is losing electricity kinda like power lines lose electricity?
I can't imagine how this would happen. The Tesla doesn't have a bi-directional charger so it wouldn't be possible for energy to flow out of the car back into the power source. And I'll just note that for the past 6 months or so, charging to a set limit doesn't necessarily mean it will go exactly to that limit and stop. I have mine set a 85% and it's frequently is at 84% when I check in the am. I'm not really concerned about it.
 
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I noticed something like this happening to me too, and I was actually thinking about posting something as well.

The other day, I set the charge limit to 60% (I don't drive much and there are tons of Superchargers nearby). I checked the app just as it finished charging and confirmed it was 60%. Two hours later when I unplugged to drive, the car was reporting 57%.

The car was kept plugged in my garage with sentry mode off. The temperature was about 63 degrees and I don't have preconditioning turned on. I hadn't checked my app or woke the car at all for the 2 hours.

One thing I can think that could explain it is battery recalibration. The car thought it was at a particular level, but it wasn't, and corrected. Today when I left, I noticed that my car was actually at 1% higher than what I had charged to yesterday, so this could be what's happening.
 
Yep. I charge at 75% and I often come back to my car showing 78%, or 73%. It doesn't matter, it's battery temperature / calibration. No one should assume this is a precise value, it's not. It's estimated current energy stored / estimated total capacity. The word estimated appears twice, and the estimate is affected by things like temperature.
 
Agreed on it moving around. I normally leave it at 63% and I see it go down to 57% or up to 65%. Seemed to do it around Feb. Starting to think it’s just some variance in the last round of updates. Car did fine thru Dec when it was 16 degrees but now it’s more in the 43 to 63 degree range.
Only other thing I did was swap usb drives with a SSD vs thumb drive but I switched it back.
 

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