The sleep on Model 3/Y is quite good as long as you aren't running sentry mode. It may lose 1% every 10 days or so (my 2018 Model 3). I can go several months without driving it or charging it and not worry. The Sleep on 2021+ cars is even better in most cases.
The older cars such as pre 2021 S/X did not have very good sleep. Yes, you need to fire up all Teslas at least once a month if they are disconnected to renew the SSL certificates. For whatever stupid reason, Tesla only generates them for 2 year validity. I don't know any good way to check the dates without root. On Sun, Nov 30, 2025 at 4:55 PM Cor van de Water <[email protected]> wrote: > If you are concerned about the Tesla discharging your pack while parked > longer time, I can recommend disconnecting the 12v battery and making sure > the main pack contactors have disconnected (Power Off). Dis will let your > Tesla keep its charge for months if necessary. Only drawbacks are that you > need to make sure you know how to jump start and if you leave the Tesla for > more than 2 months without ability to contact the Tesla Servers, it might > fail to fetch a new certificate and the Tesla engineers have chosen to make > it impossible to renew if it was not done in the 2 months. Ask me how I > know. > > The easiest way to (dis)connect 12v is the use of a remote relay that only > takes a few milliAmps for a receiver that allows you to turn the 12v on/off > with a remote, I have this in my 2013 S because it never sleeps and can > suck down its entire 85kWh pack in 2-3wks. > I had to do this when the charger failed and I had no time to fix it, 4 or > 5 months later it still had the same charge, only could no longer connect > to Tesla server... > Cor. > > On Sun, Nov 30, 2025, 4:03 PM (-Phil-) via EV <[email protected]> wrote: > >> I think Tesla can ship you a battery, but I don't know what the charges >> are, but it's probably less than $50. >> >> The likely reason it shows up after an update, is it has to stop the 12v >> support (DC-DC converter) during the update for some time, so this will >> attempt to discharge the 12v battery somewhat, and can get it low enough >> to >> trip the alert. >> >> I'm not exactly sure what the phantom draw will be at the airport in this >> state, but it could be as high as 8% per day. It depends on many factors. >> I recommend you perform the reset of the system now, and see if it comes >> back, you might be OK for a week. It will take 5 minutes and all you >> need >> is a 10mm wrench or socket to disconnect the negative lead on the 12v >> battery, then unplug the fireman connector, wait for a few seconds, then >> reconnect it, and then reconnect the 12v battery. Here is how to do >> those >> things: >> >> https://service.tesla.com/docs/Public/diy/modely/en_us/GUID-AE762FFF-8268-4BDF-9246-A2BB8D17B0B4.html >> >> On Sun, Nov 30, 2025 at 3:48 PM Mark Hanson <[email protected]> >> wrote: >> >> > Thanks Phil for your help and the thoughtful reply. >> > Seems odd to me that it does an update, then this bad 12v battery >> message >> > shows up. >> > I’m 3 hours from Richmond (Tesla) , saw one to replace my new battery >> > (replaced from Advance Auto $350) with another new battery from EBay >> > 1129182-00-b as you noted for $235. >> > I have a load battery tester so I’ll check it tomorrow but I suspect the >> > new update screwed up something. I also have my “old” 5 year battery >> that >> > load tested good I can put back in. >> > So what happens if I ignore it and it runs the dc converter while I’m >> > parked for a week at an airport (like I have to do next week)? >> > Best regards >> > Mark in Roanoke Va >> > Sent from my iPhone >> > >> > On Nov 30, 2025, at 5:07 PM, (-Phil-) <[email protected]> wrote: >> > >> > >> > Did you replace the 12v with one from Tesla or some 3rd party brand? >> > Many 12v batteries now are made with garbage lead that isn't refined >> well, >> > so ends up with a short life. Do you have any accessories hooked to the >> > 12v system? If you tap the 12v battery for anything this can be the >> > result. If you use the OEM Atlas battery it shouldl last from 3-5 >> years >> > depending on climate and your drive cycle. >> > >> > VCFRONT measures the amp-hour capacity of the 12v battery and will set >> > that alert when it detects capacity is insufficient to allow sleep, and >> it >> > will then disable sleep so you don't end up with a dead car. If you >> want >> > to double-verify this, you can reset the amp-hour counter by >> disconnecting >> > the 12v battery, then the HV, then reconnect both. The alert will go >> away, >> > It will then re-measure the capacity and the alert will return if it's >> > still too low. >> > >> > FYI: The high-quality 12v battery made by Atlas is only $100 at any >> Tesla >> > service center. (Down in cost!) Part # 1129182-00-B. You can walk in >> and >> > grab one off-the shelf. >> > >> > Here's my video on the 12v system that explains more: >> > https://www.youtube.com/watch?v=i27lApNWkyA >> > >> > On Sun, Nov 30, 2025 at 12:29 PM Mark Hanson via EV <[email protected]> >> > wrote: >> > >> >> Hi Folks >> >> The Tesla Y 2021 did another (almost daily unnecessary) update and now >> >> displays a “VCfront a402 Electrical system backup power is unavailable. >> >> Vehicle will consume more energy while idle. Software will not >> update”. >> >> Then expanding to: “VCfront a192 electrical system is unable to support >> >> all features. VCfront a182 schedule service to replace low voltage >> battery. >> >> Software will not update”. >> >> >> >> But then displayed updated software minor fixes. The pricy 12V >> battery >> >> (due to the non standard size), I replaced 6 months ago. >> >> Do I just ignore this silliness? Is there a way to reset these screen >> >> messages? >> >> Go back to a previous “update”? >> >> Best regards Mark in Roanoke Va >> >> Sent from my iPhone >> >> _______________________________________________ >> >> Address messages to [email protected] >> >> No other addresses in TO and CC fields >> >> HELP: http://www.evdl.org/help/ >> >> >> >> >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: < >> http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20251130/23967fc8/attachment.htm >> > >> _______________________________________________ >> Address messages to [email protected] >> No other addresses in TO and CC fields >> HELP: http://www.evdl.org/help/ >> >> -------------- next part -------------- An HTML attachment was scrubbed... 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