It feels kind if dumb to see such configuration and I have worries If I drain small 12v battery by using car with engine off It wouldn’t start…

  • @[email protected]
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    241 year ago

    The main reason why you will alway have a low voltage battery is safety: It is used to actuate the contactors for the HV Battery. You would not want un-switchable HV components. For example in the event of a crash the HV battery gets completely disconnected but airbags and indicators will still work. The 12v battery will get charged off the main hv battery if it gets low btw.

    • @[email protected]
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      121 year ago

      to piggyback off this, 12V components are also everywhere else, so you can use off the shelf components like lights, wiper motors, etc without having a limited production run for high voltage components, which keeps costs down. Doing it this way made it possible to add hybrid systems to traditional vehicles like a camery or an escape. This also enables you to jumpstart a hybrid with another 12V system.

      TLDR: money, compatibility, safety

    • Flying Squid
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      61 year ago

      Huh.

      The 12v battery in a hybrid doesn’t start the car like you’d expect – it provides power to the computer, relays, ECU, etc. The heavy lifting of starting the engine is actually done by the hybrid battery.

      I knew about the rest of the things it does because I can run my stereo and my headlights on my Prius without the battery indicator dropping. But I totally thought it also started the car.

      • @[email protected]
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        1 year ago

        Well in a technical sense you are also right, since the contactor for the main battery gets power from the 12v (albeit it’s not a big load) Meaning if the 12v is completely dead the hv battery will not switch on and the motor will not start.