1. Attachments are working again! Check out this thread for more details and to report any other bugs.

low mpg

Discussion in 'Generation 1 Prius Discussion' started by chaps, Jun 20, 2011.

  1. chaps

    chaps Junior Member

    Joined:
    Jun 20, 2011
    44
    3
    0
    Location:
    kenya
    Vehicle:
    2014 Prius Alpha
    Model:
    N/A
    Hi there everyone,just registered.One question though,does the 12 volts auxiliary battery affect mpg?
     
    #1 chaps, Jun 20, 2011
  2. macmaster05

    macmaster05 Senor Member

    Joined:
    Sep 27, 2009
    4,050
    729
    5
    Location:
    USA
    Vehicle:
    2010 Prius
    Model:
    Two
    Welcome, and yes! I forget exactly how it works but I think when the 12v battery is so low it needs to be replaced, the ICE compensates the 12v in order to power your electronic components including startup functions. Anecdotally, several people with low 12V batteries also have seen decreases in their mileage.
     
    #2 macmaster05, Jun 20, 2011
    1 person likes this.
  3. chaps

    chaps Junior Member

    Joined:
    Jun 20, 2011
    44
    3
    0
    Location:
    kenya
    Vehicle:
    2014 Prius Alpha
    Model:
    N/A
    Thanx alot,I got to have mine replaced.
     
    #3 chaps, Jun 21, 2011
  4. dr kegg

    dr kegg New Member

    Joined:
    Dec 12, 2010
    6
    1
    0
    Location:
    Pennsylvania
    Vehicle:
    2002 Prius
    Model:
    I
    I had to have mine replaced last year and I noticed lower mpg while it was happening. The ICE ran more at stop lights, traffic, etc. due to it compensating for the 12v.
     
    #4 dr kegg, Jun 21, 2011
  5. chaps

    chaps Junior Member

    Joined:
    Jun 20, 2011
    44
    3
    0
    Location:
    kenya
    Vehicle:
    2014 Prius Alpha
    Model:
    N/A
    I replaced the 12v battery.The mpg has improved greatly from 34.3mpg with old battery to 55.3mpg with new battery.
     
    #5 chaps, Jun 24, 2011
    1 person likes this.
  6. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,470
    6,862
    2
    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Not every way your 12 volt battery can die lowers MPG, but some do.

    I think when only one cell dies, so you have 10 volts left, the charging system wastes a great deal of energy trying to recharge to 12 volt a battery that can't get there.
     
    #6 JimboPalmer, Jun 24, 2011
(You must log in or sign up to post here.)