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

Please help me get to know my battery

Discussion in 'Newbie Forum' started by Travis Tortorige, Jul 17, 2013.

  1. Travis Tortorige

    Travis Tortorige New Member

    Joined:
    Jul 17, 2013
    21
    3
    0
    Vehicle:
    2005 Prius
    Model:
    N/A
    We have an '05 with 300,000 miles and the original battery. Is there a good way to determine battery health? Does the onboard computer display this (like a Mac computer)?

    I've read about the charge and deplete quickly theory, but that description is too vague. We get higher than EPA rated average MPG on flat ground, but we have a brutal hill climb to get home, so that really zapps the batts and the MPG.

    I only get green bars (with the top one missing) when during the 10 minute decent and full green bars for about a minute at the bottom, but it disappears immediately after the engine turns on to merge to another highway.

    Normally the battery shows half charge all the time in town with one or two bars being gained while hypermiling on flat ground.

    The battery depletes to one bar during the climb back home within about 5 minutes. It can take another 5 minutes of sitting in the driveway charging at idle to get to half again.

    So that's the story with this battery. What do you think? Is it, say, 65% healthy? More? Less?

    We live in the Denver metropolitan area at 7300' with our day to day activities at about 5600'.

    Thanks!
     
    #1 Travis Tortorige, Jul 17, 2013
  2. drysider

    drysider Active Member

    Joined:
    Apr 14, 2008
    823
    332
    1
    Location:
    Liberty Lake WA
    Vehicle:
    2012 Prius
    Model:
    Four
    The Synergy firmware is really good at maintaining the battery. Trying to outguess it probably will result in lower MPG's rather than higher. I regularly end up in the garage with two bars. Keeping the battery full is a waste of energy...use it to extend your glide rather than have a lot of bars on the display. Even at zero bars the battery is still 40% charged. To determine the batteries condition, you will need to check it's voltage vs. charge state. This will require some kind of OBD device. I use a ScanGauge, but there a lot of options. There are multiple sites on the internet that have the voltage=charge state graphs you will need.
     
    #2 drysider, Jul 17, 2013
(You must log in or sign up to post here.)