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12v battery current draw

Discussion in 'Gen III 2010+ Prius Technical Discussion' started by cobradb, Feb 26, 2012.

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  1. cobradb

    cobradb Member

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    with everything off i checked the current draw on the 12v. the car pulls a constant .6amps from the battery.
    This sounds excessive and i was suspicious when just setting over night it wants 20 amps charge and charges for quite a bit of time. (the label says it shouldn't be charged at a rate of over 4 amps) i assume this is because of the vent system.

    any comments
  2. JimboPalmer

    JimboPalmer Nadir of Wrongness

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    Did you have your Fob on you when making measurements?

    I think it is more conservative when it cannot detect a Fob.
  3. cobradb

    cobradb Member

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    good point Jim, yes im sure i did have it on me
  4. jdenenberg

    jdenenberg EE Professor

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    Don't use that charger! Use one that limits the max current to a lower value. Even at 2 amps, you can get a more than 50% charge into the battery in 10 hours. The internal Prius charging system uses a "constant voltage" (about 14v) strategy and slowly charges the little 12v battery.

    JeffD
  5. friendly_jacek

    friendly_jacek Senior Member

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    if you check with door/hatch open, there will be light on. Also the brake pressurization will eat a lot of juice when you open door first. Yes, 20A will kill that small AGM battery.
  6. cobradb

    cobradb Member

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    well, the 25 amp was a test only,, i charged at 2 amps
    i inspected the battery and found it dry- all but one cell dry. since i added water it is holding charge like new-
    BTW door light dont work if sw is off (hatch open cond)
  7. Robert Holt

    Robert Holt Active Member

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    Anyone have a list of the current draw for different systems when the car is parked and left for a week or more? Specifically the SKS sensing system, the remote lock-unlock key fob system, and whatever else remains active when the car is turned off?
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