with a cigarette charger volt meter installed...car in ready mode and in drive only shows 12.8 volts... when in ready mode and in park 14.1volts appear...can the dc to dc converter be adjusted... our 2nd generation shows 13.8 volts in drive and the 12 battery never goes dead.
when did it start going dead? how long have you had it in miles and time? any aftermarket accessories connected?
dealer has installed 2nd battery under warranty. first battery failed their battery test. they performed the software update...we gave them our car for a week and could find no problem. no after marker stuff...should not the charge be more than 12.8 while driving?
I don’t know how accurate your voltmeter is. The Gen 4/Gen 5 HEV/PHEV Prius 12-V BMS that controls the DC–DC converter voltage keeps the voltage at 12.89 V at most times, which does not charge the battery but floats it. Occasionally, it will raise it to 14.1 V or higher to charge the battery, depending on the voltage/current history, load, temperature, traction battery being charged or not, etc. There is more info here: When there will be 12-V-battery issues, when not, and what to and not to do | PriusChat And here: AGM battery for Gen 4/Gen 5 Prius/Prius Prime and observations on the 12-V charging system | PriusChat
