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Recharging / replacing 12V battery

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by RamageJ, Apr 4, 2020.

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  1. sam spade 2

    sam spade 2 Senior Member

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    It is NOT a problem.....short term.
    And the key to that discussion is: A battery charger almost NEVER really charges at it's fully rated capacity.
    If it does for more than a couple of minutes, it's likely that the battery is TOAST.
     
    #21 sam spade 2, Apr 8, 2020
  2. RamageJ

    RamageJ Junior Member

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    Cool. It only needed about 5 minutes before switching to maintain mode.
     
    #22 RamageJ, Apr 8, 2020
  3. RamageJ

    RamageJ Junior Member

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    Well, car doesn't start at all. Any threads on this issue? The polarity is correct.

    Finding some posts about checking fuses, etc. At this point, probably just having it towed if I can find it quickly.
     
    #23 RamageJ, Apr 8, 2020
    Last edited: Apr 8, 2020
  4. George W

    George W Active Member

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    When you say, "doesn't start at all", were there any dash lights when you pressed the Start button, or are we talking about completely dead?
     
    #24 George W, Apr 8, 2020
  5. SFO

    SFO Senior Member

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    After resetting or replacing the 12v battery, it will take two (2) starts (with your foot on the brake, etc) to get the vehicle into "ready" mode.

    Double check you positive/negative connections and related plugin connectors, and make sure the ground wire is secured to the body.

    Have you measured the voltage at the jump points under the hood?
     
    #25 SFO, Apr 8, 2020
  6. RamageJ

    RamageJ Junior Member

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    Yep. No dash lights. No light on the Start button. No cabin light either, for that matter. I tried pressing as hard as possible on the brake pedal and holding down Start for an extended time, pressing Start several times, pressing with and without pressing brake, etc. I always had the fob key inserted into the key slot.

    I started to tighten the ground, and my wrench generated a spark, probably because positive was still connected. I considered the time it would take to get the a/c vent out of the way, etc. to get positive disconnected and decided to use roadside assistance to tow it. (I was tired and it was getting close to 4pm).

    Pos/neg were definitely on the right wires, ground was secure. Did not measure voltage under the hood, though.
     
    #26 RamageJ, Apr 9, 2020
  7. George W

    George W Active Member

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    Here are Toyota's instructions for jumping the Prius.


    ACTIONS TO BE TAKEN WHEN BATTERIES ARE DEPLETED (a) Perform this procedure when the auxiliary battery is fully depleted. HINT: The following problems indicate that the auxiliary battery is depleted:

    • No display appears on the instrument panel when the power switch's power mode is set to ON (IG).
    • The hybrid system does not start.
    • The headlights are dim.
    • The sound from the horn is weak.

    NOTICE: Never use a quick charger.
    (1) Push the "P" position switch, and engage the parking brake.
    (2) Remove the key from the key slot.
    (3) Using a booster cable, connect the rescue vehicle's 12 V battery positive (+) lead to the stalled vehicle's relay block positive (+) terminal and the negative (-) lead to the suspension support's nut on the right side.
    (4) Start the engine of the rescue vehicle and run the engine at a speed slightly higher than the idling speed for 5 minutes to charge the auxiliary battery of the stalled vehicle.
    (5) Depress the brake pedal and push the power switch to start the hybrid system. If the hybrid system fails to start and the master light turns ON, the HV battery may be depleted.
    (6) Disconnect the booster cable in the reverse order of the connection procedure.

    NOTICE: If the auxiliary battery needs to be replaced, replace it only with a 12 V battery specially designed for use with the PRIUS
     
    #27 George W, Apr 9, 2020
    Last edited: Apr 9, 2020
  8. sam spade 2

    sam spade 2 Senior Member

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    It was not the wrench that generated the spark, it was the negative cable trying to make connection but failing.
    If you had finished the job, likely it would have worked fine.
     
    #28 sam spade 2, Apr 9, 2020
  9. RamageJ

    RamageJ Junior Member

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    Gotcha. I don't like to mess around with generating sparks. The shop cleaned pos and neg connections and tightened them, and it's working now. Maybe I didn't have the neg cable tight enough, although it seemed pretty solid.

    If that battery was easier to remove, I would have finished the job myself.
     
    #29 RamageJ, Apr 14, 2020
    bisco likes this.
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