I just read Syonyk's blog post on the Model S 12 volt battery issues and charging patterns from 2016, which is really interesting. I guess at that time there were some issues with how the 12 volt battery was charged and used and there were a lot of failures at that time. I was wondering if anyone has looked at data logs pertaining to the voltage (etc) vs time for a model 3 12 volt battery (basic data logging). This would presumably show how often it charges, how deeply it discharges before charging, whether it uses a float charge state much and maybe some other cool stuff. This should be intimately connected to "vampire drain" and I think would be different pre July 2019 (when drain was about 1% = 750 watt-hours per day, vs post July 2019 when drain is a lot less (maybe 200 watt-hours per day? It is so low now it is a bit difficult to measure accurately unless you leave your car for a couple of weeks or more.)
On those 2016 data logs, Syonyk found that the battery was charging about 50% of the time, but that the charging stopped before it got to a fully charged state, with is not a good protocol for a AGM acid battery at all. (It was almost as if they were following a Li-ion protocol?) Probably now it is a much better and different charging pattern now in the 3. I would be interest what people think or if anyone has had issues with their 12 volt battery. I have measured the 12 V battery voltage under the frunk and each time I found about 14.9 volts, which I am am pretty sure means the battery is charging. (I think that is a pretty high charging voltage btw.) I have never been able to catch the battering in a not charging state, which i think would be indicated by a voltage between about 12.4 and 12.8 volts, or in a float (trickle) charge state (13 to 13.9 volts or so). Does any one know of any data logging or info on the 12 volt? Does it discharge as low as 12.4 V (50%) before charging kicks on or does it start charging at a higher voltage like 12.55 volts (70%). Does it tend to float charge while driving??
On those 2016 data logs, Syonyk found that the battery was charging about 50% of the time, but that the charging stopped before it got to a fully charged state, with is not a good protocol for a AGM acid battery at all. (It was almost as if they were following a Li-ion protocol?) Probably now it is a much better and different charging pattern now in the 3. I would be interest what people think or if anyone has had issues with their 12 volt battery. I have measured the 12 V battery voltage under the frunk and each time I found about 14.9 volts, which I am am pretty sure means the battery is charging. (I think that is a pretty high charging voltage btw.) I have never been able to catch the battering in a not charging state, which i think would be indicated by a voltage between about 12.4 and 12.8 volts, or in a float (trickle) charge state (13 to 13.9 volts or so). Does any one know of any data logging or info on the 12 volt? Does it discharge as low as 12.4 V (50%) before charging kicks on or does it start charging at a higher voltage like 12.55 volts (70%). Does it tend to float charge while driving??
