VCFRONT in the Tesla monitors the amp-hour capacity of the lead-acid battery. When it drops too low, you get that alert.
To change it, disconnect the negative terminal, then go into service mode and stop 12v support. If you don't do this the alert will stay until you do. On Mon, Jul 28, 2025 at 7:21 PM Jay Summet via EV <[email protected]> wrote: > I would not be surprised if it is almost dead. 5 years appears to be > about the standard runtime for most car accessory batteries. [I've had > the one in my Leaf and a Nissan Altima both die around that timeframe..] > > > I don't know if the Tesla system is doing a calendar reminder, or if > they are doing diagnostics based upon the battery voltage and capacity. > > Jay > > On 7/28/25 21:27, Mark Hanson via EV wrote: > > Hi Folks, > > > > I got an alert on my 2021 Tesla-Y app to change the 12V aux lead battery > > after about 4.5 years 126K miles of operation. > > > > It looks like I need to go into the menu>service>PowerOff selection > before > > just plucking out the battery. > > > > In the 2013 Leaf I just changed the 12V battery without fanfare. Also in > > the 2020 Bolt after 5 years of operation. > > > > Is 5 years the recommended aux 12V change interval? - or should I do a > load > > test first before just changing it at a fixed time/mileage interval? > > > > > > Have a renewable energy day, > > > > Mark > > > > Mark E. Hanson > > 184 Vista Lane > > Fincastle, VA 24090 > > 540-473-1248 phone & FAX, 540-816-0812 cell > > REEVA: community service RE & EV project club > > Website: www.REEVAdiy.org (See Project Gallery) > > UL Certified PV Installer > > My RE&EV Circuits: www.EVDL.org/lib/mh > > REEVA Demo: http://youtu.be/4kqWn2H-rA0 > > Fincastle Solar Weather Station > > > > > > > > _______________________________________________ > > 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/ > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20250728/73470a29/attachment.htm> _______________________________________________ Address messages to [email protected] No other addresses in TO and CC fields HELP: http://www.evdl.org/help/
