12 volt Battery Status Indicator on Gen 2

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Skateruk, Nov 14, 2013.

  1. Skateruk

    Skateruk Member

    Joined:
    Nov 13, 2013
    125
    28
    0
    Location:
    Nottingham, UK
    Vehicle:
    2009 Prius
    Model:
    III
    All, is there anywhere hidden in the Multi Information Display panel a precise electronic indication of the battery's charge state without physically having to dig the thing from out the back?
     
  2. Prius_Cub

    Prius_Cub Member

    Joined:
    Feb 12, 2013
    152
    59
    0
    Location:
    Radford, VA
    Vehicle:
    2008 Prius
    Model:
    II
  3. Skateruk

    Skateruk Member

    Joined:
    Nov 13, 2013
    125
    28
    0
    Location:
    Nottingham, UK
    Vehicle:
    2009 Prius
    Model:
    III
    Thanks for your reply Prius Club, I will check out your suggestions!
     
  4. Skateruk

    Skateruk Member

    Joined:
    Nov 13, 2013
    125
    28
    0
    Location:
    Nottingham, UK
    Vehicle:
    2009 Prius
    Model:
    III
    Just tried the 12volt battery test after driving the car for about 20mins. When I parked up, the HV battery indicater on the main screen was showing green bars. The test showed the battery at 12.2 volts, presumably this is ok? The battery itself looks to be an original, certainly not a "yellow top"
     
  5. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,089
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    Run the test after the Prius has set overnight before you drive it.

    Need the three values

    Accessory Mode:
    Ignition On Mode:
    Ready Mode:

    Here is a chart that you can relate to concerning voltages on a AGM type battery. FWIW, yours sounds a little weak to me. Will know more once we see all three figures.

    Battery SOC Chart.jpg
     
  6. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,877
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    I would not describe the 12 volt battery readout on the MFD as precision.
    On test I have carried out on a number of gen2's the display has been as much as 0.5 volts out against a calibrated DVM, and in every case under reads the actual voltage.
    My suggestion is you measure the voltage at the battery while also using the MFD. This way you can see what the error is if any and then apply the offset to any further reading using the MFD.

    John (Britprius)
     
  7. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,089
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    I do agree with John about the MFD not being a precise instrument. If you don't want to pull out the back panels to get to the battery post, you can check the voltage at the jump post in the main fuse panel under the hood. Generally speaking, there is usually about a .2 volt drop in measurement from the battery posts versus the jump point. I believe that is due to resistance. You may find less or no drop whatsoever.
     
  8. Skateruk

    Skateruk Member

    Joined:
    Nov 13, 2013
    125
    28
    0
    Location:
    Nottingham, UK
    Vehicle:
    2009 Prius
    Model:
    III
    Hi Guys re my post above where I checked the Accessory mode, I have just carried the 3 stage test suggested by Dorunron. To recap, the Accessory voltage shown yesterday was 12.2. This morning after standing all night and with a temperature around 3 degrees C, the results were: Accessory = 9.6, Ignition = 9.4 and Ready = 14.3.
    What are your thoughts on these readings please? Thanks in advance by the way!
     
  9. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,089
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    That battery is dead. Get a new one. Look at the chart I posted above.

    A new fully charged AGM type battery should read the following when running the test.

    Accessory Mode: 12.6 volts or higher
    Ignition On Mode: 12.4 volts or higher
    Ready Mode: 13.8 to 14.2 volts
     
  10. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,877
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    Those voltages are very low and indicate an immediate replacement of the battery is required.
    When the new battery is bought check it's voltage before fitting. This for a fresh fully charged battery should be 12.8 to 13.0 volts or may be a little higher. If lower than 12.8 volts charge before fitting.
    I would not accept a battery with a voltage below 12.2 volts as partial discharged batteries sitting on a shelf sulfate the internals quickly leading to a shorter life and capacity.
    Can you give some guide to your location in your avatar as we would then be able to guide you to suitable replacement batteries.
    As Dorunron pointed out above the voltage drop shown at the jump point of 0.2 volts may not sound much, but when measuring the voltage of a lead acid battery that sort of discrepancy is very significant on it's level of charge.

    John (Britprius
     
  11. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,089
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    As John said above, don't accept a battery that is not fully charged. 13.8 volts is a little high though, I think he mistyped that one, probably should read 12.8 volts. Same for 13.2, probably meant 12.2 (discharged and sulfated).

    It is important that a new battery is fully charged BEFORE you install it in the Prius. The charging system is not very robust.

    Use a digital voltage meter. Measure the voltage at the posts BEFORE you install it. If it reads less than 12.8 volts, it is NOT fully charged.

    Battery SOC Chart.jpg
     
  12. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,877
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    Thanks Dorunron yes miss typed, and now corrected thanks.

    John (Britprius)
     
  13. Skateruk

    Skateruk Member

    Joined:
    Nov 13, 2013
    125
    28
    0
    Location:
    Nottingham, UK
    Vehicle:
    2009 Prius
    Model:
    III
    Thanks for all your input guys, it's much appreciated.
    Hi John, for the record I am in Nottingham. Do you know any good battery suppliers, and should I go for the Optimax or stick with the original make installed by Toyota? If I go the Optimax route, will I have to make any modifications ie to black earth cable, vent etc? I ask because I'm not particularly mechanically minded, and in any event would hate to cause a massive electrical short and blow the main battery etc!!!
     
  14. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,877
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    The Optima is way over priced and with a comparatively short guarantee. Bosh, Varta, Exide all make direct fit batteries from around £45 with up to 5 year guarantee. I think you will find the OEM battery is about £90. Do not go to Hal--rds they are expensive and don't even list the correct battery. I will post more details a little later. I have a post on here detailing how to fit a high capacity mobility battery if you are up for only minor DIY.

    John (Britprius)
     
  15. Skateruk

    Skateruk Member

    Joined:
    Nov 13, 2013
    125
    28
    0
    Location:
    Nottingham, UK
    Vehicle:
    2009 Prius
    Model:
    III
    Thanks for the update John. I like the idea of a direct fit battery from a well know manufacturer - might even get my hands dirty! lol
     
  16. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,877
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    When buying a Prius battery the things to look out for are:-
    It has an external vent
    The terminals are the small JAP terminals not the larger standard imperial.
    When the terminals are closest to you the positive (+/red) terminal is on the left. Many batteries advertised are not being the other way round.
    Examples of the correct batteries from Ebay.
    Item no:- 350869455183, 370570483080.
    These batteries should be available at your local motorist shop and there are others such as Lucas. If you pay a little more you can get 5 year guarantee versions.
    If you need any more help just ask.

    John (Bitprius)
     
    Skateruk likes this.
  17. Skateruk

    Skateruk Member

    Joined:
    Nov 13, 2013
    125
    28
    0
    Location:
    Nottingham, UK
    Vehicle:
    2009 Prius
    Model:
    III
    Hi John, I spoke to Formula1 who can fit a direct replacement battery with a 3 year guarantee for £64 fully inclusive. Their price varies according to the length of the batteries guarantee. I will call in and talk to them next week re the options. Many thanks for your help and everyone else's.
     
  18. MikeSF

    MikeSF Member

    Joined:
    Apr 19, 2006
    407
    17
    0
    Location:
    San Francisco
    Vehicle:
    2006 Prius
    Hmmm, I just checked my battery with a DVM and read 12.02V, it's the original 2006 battery the car was off over night, going by that chart I'm probably in need of a battery change?

    I tested it out of curiousity seeing as there was a post about the MFD acting strange when your battery is going dead, not registering touches, sometimes registering touches at the wrong location (try to turn on environmental controls is pure madness sometimes). Now my battery may be low AND my MFD is busted, but I'm curious if I should replace the battery first then see if that affects the MFD usage.
     
  19. Prius_Cub

    Prius_Cub Member

    Joined:
    Feb 12, 2013
    152
    59
    0
    Location:
    Radford, VA
    Vehicle:
    2008 Prius
    Model:
    II
    Definitely replace the battery first, see if that's causing your MFD to act crazy. if not, at least you won't have to worry about being stuck somewhere in need of a jump.

    HTC Evo 3D
     
  20. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,877
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    Mike I do not like to be the bearer of bad news, but I doubt very much the low battery is causing your MFD problems. Once the car is made ready the voltage will be at around 14 volts and the 12 volt battery can actually be removed and the car will still operate normally.
    I agree your battery is at the point of expiring and is due for replacement.

    John (Britprius)
     
Loading...