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Highlander 2022 Charging Voltage Drop

jebelhafit
jebelhafit Member Posts: 17
in Battery/Electrical & Solar
I have a 2022Toyota Highlander and have an annoying charging issue.  When I start the vehicle, the alternator provides 14.16 V which is more than sufficient for my T@B 2015 with an Isotherm 12V fridge.  After the car is warmed up the charging voltage drops to 12.36 volts  which leaves me at the end of the day with trailer batteries at 95%. Not the end of the world, but annoying none the less.  Does anyone know how to over-ride the "smart car" voltage drop?  
Toyota has not been of any help to date.
Thanks,
Gary
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  • Marceline
    Marceline Member Posts: 1,745
    jebelhafit said:
    I have a 2022Toyota Highlander and have an annoying charging issue.  When I start the vehicle, the alternator provides 14.16 V which is more than sufficient for my T@B 2015 with an Isotherm 12V fridge.  After the car is warmed up the charging voltage drops to 12.36 volts  which leaves me at the end of the day with trailer batteries at 95%. Not the end of the world, but annoying none the less.  Does anyone know how to over-ride the "smart car" voltage drop?  
    Toyota has not been of any help to date.
    Thanks,
    Gary
    I think that the most common solution is to install a DC-DC charger. 
    San Francisco Bay Area
    2013 CS-S us@gi
    2015 Toyota Tacoma PreRunner Double Cab
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  • Sharon_is_SAM
    Sharon_is_SAM Member Posts: 10,061
    It was also suggested to turn on your headlights and that may boost the voltage on some vehicles.
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • Yoshi_TAB
    Yoshi_TAB Member Posts: 566
    Hi, 

    They can not be overridden as they are controlled by the vehicles ECM.  They are designed to reduce the  voltage load of the vehicle and thus  mechanical load of the vehicle to increase gas mileage and lower emissions . I’m sure there is a hack to use of those OBD ECM devices.  As the other posted said, best if you want to charge your battery via your alternator is to use a DC DC charger. 
    2025 360 CS 
    2021 TAB 320 BD (w/new owner having fun)
    2021 Jeep Grand Cherokee
    Southern Maryland
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  • jebelhafit
    jebelhafit Member Posts: 17
    Many thanks for the info.
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  • jebelhafit
    jebelhafit Member Posts: 17
    I Just returned from a brief 3-day camping trip and was able to outsmart the "smart" generator thanks to Sharon's advice. When the 2022 Highlander's headlights are on the charging voltage jumps from 12.3V to 13.5V which is more than enough to charge my trailer batteries to 100% as well are run the Isotherm fridge.
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  • Sharon_is_SAM
    Sharon_is_SAM Member Posts: 10,061
    Good to know @jebelhafit.  I love a simple solution.  I drive with my headlights on all the time.  I got in the habit from parking in a dark garage at work.  I have read that there is about a 5% reduction in daytime crashes when you use your headlights.  Nice little added margin of safety.
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • ScottG
    ScottG Administrator Posts: 5,655
    edited September 2023
    Turning on your headlights while towing also activates the trailer's running lights. More lights = greater visibility--always a good thing, but particularly warranted when driving with extra challenges such as towing a trailer. 
    Although I turn my lights on whenever I tow, unfortunately doing so does not bump up the output of the smart generator on a Nissan Frontier.
    2015 T@B Max S (320)
    2015 Nissan Frontier SV V6 4x4
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