Alas, murdering the 12v battery after a car sits for a month is a standard "feature" of just about every vehicle today.
I wonder when that became the norm. My '65 Corvair could sit for 6 months and still start in the spring. -- Excellence does not require perfection. -- Henry James But it *does* require attention to detail! -- Lee Hart -- Lee A. Hart https://www.sunrise-ev.com -----Original Message----- From: Electric Vehicle Discussion List <[email protected]> Sent: Aug 15, 2025 10:11 AM To: Electric Vehicle Discussion List <[email protected]> Cc: jamie <[email protected]> Subject: Re: [EVDL] Telsa left to sit a 0% : recovering the HV, Plug in while on a long trip? Good to know. A de facto auto-bricking feature that kicks in after being parked for a few months doesn't seem like a major selling point. For that matter, having to accept a steady 1+%/day battery drain from the main pack doesn't seem particularly efficient. Is that typical of other brands as well? Nor does forced sacrificing of the accessory battery when the main pack gets too low. Couldn't some brilliant engineer do better? Perhaps design actual off switches to delay/avoid these conditions? On 8/15/25 8:29 AM, Kevin Horton via EV wrote: > The current version of the Service Manual for my 2022 Tesla Model S has the > following in General Information -> Charging -> General: > > Discharging the HV battery to 0% state of charge can permanently damage the > > battery. To protect against a complete discharge, the vehicle enters a low > > power consumption mode when the state of charge drops below 6%. In this > > mode, the battery stops supporting the onboard electronics to slow the > > discharge rate. > > NOTE > When the low power consumption mode is active, the auxiliary 15V battery is > no longer being charged and can completely discharge within hours. If this > situation cannot be avoided, disconnect LV power (refer to procedure) from > the vehicle to preserve the 15V battery. If a complete discharge does occur > then the vehicle will need to be jump-started and the 15V battery must be > replaced. > > ======= > > The Owner's Manual has the following in the Sentry Mode section: > > Sentry Mode requires your Battery to be at least 20% charged. If the > > Battery falls below 20%, Sentry Mode turns off and the mobile app sends you > > a notification. Power consumption may increase when Sentry Mode is active. > > It has the following in the Battery Care section: > > Even when Model S is not being driven, its Battery discharges very slowly > > to power the onboard electronics. The Battery can discharge at a rate of > > approximately 1% per day, though the discharge rate may vary depending on > > environmental factors (such as cold weather), vehicle configuration, and > > your selected settings on the touchscreen. Situations can arise in which > > you must leave Model S unplugged for an extended period of time (for > > example, at an airport when traveling). In these situations, keep the 1% in > > mind to ensure that you leave the Battery with a sufficient charge level. > > For example, over a two week period (14 days), the Battery may discharge by > > approximately 14%. > > Kevin > >> On Aug 15, 2025, at 8:21 AM, Collin Kidder via EV wrote: >> >> Well, they do some of that. Sentry mode will disable at some point, I think >> 30% SOC. The car won't enable those sort of "bonus" features at low SOC but >> it seems that otherwise it's perfectly fine with trying to kill the HV >> battery to save your $200 12V battery and still be able to run the >> computers. That does seem to be a rather poor choice. Personally, I'd >> rather ruin the 12v battery and leave the main HV battery at 20% or >> something. I believe most other current EVs (Bolt, Mach-E, etc) do disable >> pretty much everything to do with the HV battery at a certain SOC so that >> it stays good even if that means your 12V battery has to die. >> >> On Thu, Aug 14, 2025 at 9:37 PM Bryce Nesbitt via EV >> wrote: >> >>> And YES this is a serious design flaw. >>> >>> The car could implement several battery actions: turn off sentry, camping, >>> and eventually LTE data. Have a "battery saver" mode that wakes up >>> once a week to call >>> Tesla over mobile data, but that's it. >>> _______________________________________________ >>> 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: >> _______________________________________________ >> Address messages to [email protected] >> No other addresses in TO and CC fields >> HELP: http://www.evdl.org/help/ >> > > _______________________________________________ > Address messages to [email protected] > No other addresses in TO and CC fields > HELP: http://www.evdl.org/help/ > _______________________________________________ Address messages to [email protected] No other addresses in TO and CC fields HELP: http://www.evdl.org/help/ _______________________________________________ Address messages to [email protected] No other addresses in TO and CC fields HELP: http://www.evdl.org/help/
