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Battery drains to 11.9-12.0v when key on

Discussion in 'Generation 1 Prius Discussion' started by boostedsil40, Dec 2, 2018.

  1. boostedsil40

    boostedsil40 Junior Member

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    My gf 2001 Prius has a intermittent no crank where you have to turn key a few times to get car to crank,today I replaced ignition switch which was loose and thought it would solve issue along with terminal cleaning and inspection,in the end the intermittent no crank remained,the battery is 2 months old and we got the new battery in hopes of fixing this issue.today I load tested battery and it passed but I decided to hook up multimeter and see what happens when I crank engine.everything is normal with battery at 12.6-12.8v but when I put key in the "on" position just past account and right before you crank the battery jumps down to around 12.1vv then when I press the brake it drops too 11.9v but after 20 seconds rises to the 12v area.what the heck is going on?I realise this would not be enough to crank a regular car but I read the Prius doesn't need as much voltage since it just powers electronics.is this normal?is the battery the prime suspect even though it past load test?please respond with insite and what steps should be taken next and thank you.
     
    #1 boostedsil40, Dec 2, 2018
  2. bisco

    bisco cookie crumbler

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    i don't think so. i would start by checking for trouble codes
     
    #2 bisco, Dec 3, 2018
  3. boostedsil40

    boostedsil40 Junior Member

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    Bump' I'll have to drive a bit to get codes to show as they were erased when cleaning cables on battery please anymore input?
     
    #3 boostedsil40, Dec 3, 2018
  4. ChapmanF

    ChapmanF Senior Member

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    I don't think there's anything surprising about those voltages (and they very probably would crank a regular car). When you turn the key ON, a number of electrical loads come online, and that pulls the measured voltage down. Pressing the brake activates the brake system and the brake lights, and may also start the brake pump for several seconds, which will pull voltage down further while it's running, and the measurement will recover when the pump stops. Nothing unusual in all of that.

    First things first ... when you say "turn key a few times to get car to crank", what do you mean by "crank"? You realize that you have started a Prius as soon as the word READY shows up on the dash, whether anything cranked or not, right? Sometimes all you'll hear is three clicks. If READY shows up, drive the car.

    -Chap
     
    #4 ChapmanF, Dec 4, 2018
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