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

13.4v while driving?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusGuy32, Apr 16, 2014.

  1. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,411
    506
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2015 Prius
    Model:
    Four
    I just replaced my 12v battery a month or two ago with a Yuasa unit from my Toyo Dealer (y)

    It checks out great. When I use my DVM on the battery posts in the morning, I get 12.8v. I finally got a GOOD battery after dealing with bad Craptimas!!

    Im now seeing something Ive never seen before - I sometimes drive around with SG2 hooked up. Ive noticed that in the morning my Prius is always at 13.9-14.1v as Im driving. But now that its gotten warmer out, when Im driving home in the afternoon, the voltage goes up to 14.0v then after a while the Prius is charging at 13.4v -13.5v. If I turn on the headlights or the fan, it goes back up to 13.9-14.1v.

    I may be wrong, but I surmised that the Prius detected my 12v was fully charged, and the Prius just chilled out charging it. Maybe there isnt much of load on it, the battery is warm (ambient temperatures are warmer) and happy?

    Am I right with my assumption or is my Prius about to surprise me? lol
     
    #1 PriusGuy32, Apr 16, 2014
  2. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,103
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    I do believe you are right with your assumption. I have seen similar voltages on the old Gen II I used to drive. Sounds like that battery I recommended is doing the job for you. ;)

    Have fun! I know I am with this new one. Actually got 67 MPG on a 24 mile run in city traffic. Lots of side streets, using the "shortest route" on the nav. I thought I liked the Gen II. I LOVE this new Gen III. Still breaking it in. Already got over 1000 miles on it.

    Ron
     
    #2 dorunron, Apr 16, 2014
    PriusGuy32 likes this.
  3. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,411
    506
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2015 Prius
    Model:
    Four

    YES Thanks again!!! Im very glad I got the Yuasa this time.

    Jealous of your G3 mileage... Ive been having the itch for a while now, lol. Who knows... you did talk me into a battery, maybe if you keep building up the G3, I will find myself at the dealership test driving one soon! (y) :D
     
    #3 PriusGuy32, Apr 16, 2014
    dorunron likes this.
  4. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,103
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    Hey Prius Guy 32, did your new battery look like this one?

    OEM Battery.JPG
     
    #4 dorunron, Apr 16, 2014
  5. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,411
    506
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2015 Prius
    Model:
    Four

    Yeah, it was pretty much identical if I remember.

    [​IMG]
     
    #5 PriusGuy32, Apr 16, 2014
    dorunron likes this.
  6. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,103
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    The trip odometer was reset when I filled up last week. Over 300 miles on this tank so far. MPG was showing 54 something when I checked it this morning. Still have another 200 to go before DTE reads 0. Thinking about taking it down to DTE 50 and then refill. With no bladder, I will definitely add more fuel when it comes time to fill up, but the range should be further too. I figure I will probably put about 9 to 10 gallons of fuel in when I fill up. Figuring max of $40, probably closer to $35. Fuel is running $3.399 right now. Think it is going up again.

    But I am really loving it. Lots of new stuff to play with. And the HSI indicator sure beats the arrows stuff on the MFD when it comes down to P&G. It is real easy to feather the pedal in comparison to the Gen II.



    Ron
     
    #6 dorunron, Apr 16, 2014
  7. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,215
    1,200
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    Yeah PG, several of us have noticed that as well. I reported it here a few years ago and it caused a bit of controversy at the time because the majority of people had never seen it happen and thought it was anomalous. Since then however more and more people have noticed and reported it.

    A lot of people will never notice it, because it wont do it if it's too cold or if you're using electrical accessories, but it works like clockwork for me. If I drive without the fan on then at about 25 to 30 minutes into the journey it will make the transition (to the lower voltage), every time right on cue.

    The consensus now is that it *is* just a two stage (charge/float) charging system, though it does still have some slightly weird behavior as to when it will and when it wont enter that second stage.

    BTW. Here's a slightly weird one. Stop and put the car in "P" and it will immediately jump back to full volts.
     
    #7 uart, Apr 17, 2014
  8. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,103
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    Uh huh, noticed the jump in voltage when in P too! Had forgot about that until uart mentioned it!

    Ron
     
    #8 dorunron, Apr 17, 2014
  9. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,411
    506
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2015 Prius
    Model:
    Four
    Ha... interesting. Im glad its not a problem. I was thinking...crap, now I finally got a nice healthy 12v battery, and the Prius is going to reject it, lol.

    I guess I was shocked because 99% of the time Ive owned my car its had bad Optimas. So I remember with the Optima that I could never get to hold a charge over 12.2v, sometimes I would be driving the Prius and it would be at 14.4v :eek: - I never ONCE saw it charge the 12v below 14.1v with the Optima. :mad:
     
    #9 PriusGuy32, Apr 17, 2014
(You must log in or sign up to post here.)