Replaced 12v battery after red triangle warning - still low voltage

Discussion in 'Gen 2 Prius Main Forum' started by capper14, Apr 30, 2020.

  1. capper14

    capper14 New Member

    Joined:
    Apr 30, 2020
    4
    0
    0
    Location:
    Seattle
    Vehicle:
    2005 Prius
    Model:
    N/A
    Hi there,

    Last week my 2005 prius had the red triangle of death for the first time. After researching the issue, I decided to check the 12v battery compartment for flooding. I was surprised to find about 3 inches of standing water in there. I removed the 12v battery, drained the water and dried out the battery well. After reinstalling the 12v, the car ran well for a day. Then the red triangle of death returned.

    Further research on the forum helped me test the voltage readings on the display. It was low, registering about 10.5 volts in ACC. I purchased a new 12v battery online and it arrived today. I just installed it and after driving for 5 minutes, the red triangle returned.

    I have a brand new 12v batter installed and it's still registering lower than recommended voltage. It's showing about 11.6v in ACC currently. I'm not sure what other issues could be present and would love some recommendations of next steps to take.
     
  2. 05PreeUs

    05PreeUs Senior Member

    Joined:
    Oct 1, 2016
    1,096
    543
    0
    Location:
    MSP
    Vehicle:
    2005 Prius
    Model:
    N/A
    "New" does not mean it is a quality part or that it was fully charged when installed... it SHOULD mean both those things, but sadly not necessarily true.

    The 12v battery is maintained by the inverter, where the high voltage is lowered to "charge" the 12v battery. If there is an over-night drain on the 12v, the inverter will NOT be able to correctly maintain the 12v battery as it really cannot "charge" it like a traditional alternator or battery charger could.

    Was there a fat spark when you connected your new battery? If so, I would have the vehicle checked for an excessive parasitic drain. If not, the new battery may not have been fully charged when installed and given that the inverter effectively cannot charge it, you may have to apply a battery charger to bring it up to full charge. The inverter should be able to take it from there, if it is working correctly.
     
    George W likes this.
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    11,173
    8,134
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    When you say "on the display", do you mean in the Vehicle Signal Check screen on the MFD ?

    That came up in another thread just last night. I beat you by 0.4 volts, mine showed 11.2 in ACC and that's with a splendid new Toyota battery from just this last winter that got a full charge before installation, and there aren't any problems with my car.

    I would suggest stressing less about the battery right now, and just proceeding to ask your car why it is lighting the triangle. From your post it sounds like you haven't done that yet.
     
  4. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    8,997
    11,017
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    As Chap said, the red triangle means read the codes to find out which of the gazillion things that can light that triangle lit it. And use a Prius literate reader, not a generic one that doesn't do hybrids. Lots and lots of threads here about that.
     
  5. capper14

    capper14 New Member

    Joined:
    Apr 30, 2020
    4
    0
    0
    Location:
    Seattle
    Vehicle:
    2005 Prius
    Model:
    N/A
     
  6. capper14

    capper14 New Member

    Joined:
    Apr 30, 2020
    4
    0
    0
    Location:
    Seattle
    Vehicle:
    2005 Prius
    Model:
    N/A
    Thanks everyone. I really appreciate this forum. At this point I'll just order a prius specific code reader and see what it pumps out.
     
  7. sam spade 2

    sam spade 2 Senior Member

    Joined:
    Mar 31, 2018
    4,529
    1,892
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    There may be other problems too but...............
    Almost without exception, batteries shipped directly to you MUST be manually charged before being used
    AND they have an instruction sheet saying that.
     
  8. capper14

    capper14 New Member

    Joined:
    Apr 30, 2020
    4
    0
    0
    Location:
    Seattle
    Vehicle:
    2005 Prius
    Model:
    N/A
    Hmmm. Mine didn't have instructions other than how to dispose of my old battery.
     
  9. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    90,868
    40,823
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    what brand did you buy?
     
  10. sam spade 2

    sam spade 2 Senior Member

    Joined:
    Mar 31, 2018
    4,529
    1,892
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    Regardless, you should manually charge your new battery and test the charging voltage in the car BEFORE you run off chasing potential ghosts.
    But given the age of your car, you probably are looking at other major problems developing.......like a hybrid battery.
     
    George W likes this.
  11. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    907
    490
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    Exactly. My brand new 12V was a volt low, had to charge it before using it
     
  12. Calimobber

    Calimobber Member

    Joined:
    Jun 24, 2019
    69
    56
    0
    Location:
    Death Valley
    Vehicle:
    2008 Prius
    Model:
    ----USA----
    Dont stress about charging it and just drive it a while. Either go for a drive to get out of the house or even just start the car and leave it parked in the driveway for like 30min . Also when on acc mode things are being powered which is causing your voltage to be low. Only way to test the battery is with eveything off it should be over 12v

    For fun you can power the car up and then check the battery. just have it in park and e brake one. The volts will be 13v+

    If the trouble code stays on then you can just stop at autozone and they will check the code for you. I dont have anything special for checking and mine showed all my 240v battery issues just fine.
     
  13. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    11,173
    8,134
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    ... which only tells you that the charging system is working. You aren't able to get a battery voltage measurement in that condition, because your meter will be showing you the charging voltage.
     
  14. 05PreeUs

    05PreeUs Senior Member

    Joined:
    Oct 1, 2016
    1,096
    543
    0
    Location:
    MSP
    Vehicle:
    2005 Prius
    Model:
    N/A
    Um, no. The DC-DC converter is NOT designed to "recharge" the 12v, only to maintain system voltage in use.

    Nope. If the car is "on" the DC-DC is powering it, if your voltage is much below 13.5vdc in that condition, the DC-DC is not working correctly or the 12v is badly discharged and MUST be fully recharged using an off-board charger.
     
  15. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    11,173
    8,134
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    I've 'recharged' a Gen 2 by leaving it on for a while after a severe discharge, but it sure didn't take 30 minutes. It's a forty-some-amphour battery, and the charging system might be seen putting 7 amps or so into it initially but quickly falling back to under 5 amps for the bulk of the time. So it's an overnight sort of proposition, if you have a place to safely leave the car in READY overnight.

    Of course if you have a ten or twelve hour road trip you need to make, you can do it that way too. It won't be fully recharged by your first stop for gas, but it will be enough to start up again.
     
  16. sam spade 2

    sam spade 2 Senior Member

    Joined:
    Mar 31, 2018
    4,529
    1,892
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    Sorry but most of that is BAD advice.
    Many cars these days will NOT fully charge an almost dead battery, no matter how far you drive it (well, hundreds of miles maybe).
    Second, 12.0 volts is half discharged and is NOT considered "good".

    If your battery is really low, it NEEDS to be manually charged before testing.
     
    George W likes this.
  17. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    907
    490
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    Incorrect. The 12V charging on a Gen2 is not quick. It will take a very long drive to top-off a new battery which sat in a warehouse for months. You are better off spending an afternoon letting AutoZone charge It for you and then be done with it.
     
    05PreeUs likes this.
  18. Skibob

    Skibob Senior Member

    Joined:
    Sep 14, 2018
    2,880
    1,464
    0
    Location:
    Northern California
    Vehicle:
    2006 Prius
    Model:
    N/A
    Did you get something that looked like a turtle on the MFD in addition to the Red Triangle? Generally a low 12v voltage does not make the red triangle go on.
     
Loading...