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12v battery at 10v

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by AlwaysDrivingFL, Oct 1, 2020.

  1. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    I bought a new Yellow Top battery from Auto Zone (? i mix them all up) a couple of months ago. Batter wasn't more than 6 months old. A few weeks ago i came home in the evening and the next morning I had a red triangle of death. It had been a bad week, no one could find the bag my scan gauge is in to read the codes. I finally last week tried the onboard check and to my surprise the 12v battery was at 10.4v. UGH.

    Jumper cables were in a car out of town, i had an alternate vehicle to drive so i was... just now we "jumped it" (of course following the directions) and waited 5 minutes and it was still ROD and the batter check was reading 10.5v.

    Obviously the battery is part of the problem If we unhook it from the car can we run a plug in charger on it? Just take it back to Auto Zone? Leave the jump on it longer?

    Off to take the kid to an appointment - i'll read more in a bit on what i can do.
    Thanks for any input!
     
  2. SFO

    SFO Senior Member

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    Be sure to check for tight connections on and around the 12v, and the negative strap attached at the body, where rust can form.

    What kind of amperage, and is it an AGM compatible charger?
     
  3. ChapmanF

    ChapmanF Senior Member

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    If you can start the car with a jump, do you have a safe location to keep the car in READY for 15 hours or so? It takes about that long from a full discharge, and a Gen 2 will not recharge the battery at a rate that is particularly hard on it (which is why it takes so long).

    In other cars that would recharge a dead battery at a battery-clobbering rate as soon as the engine started, I used to prefer taking the battery out to a slow charger and putting it back the next day. But with a Gen 2 that's kind of what happens in the car anyway.
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Get a smart* charger, around 3.5 amp max (max amp's spec'd in second gen Owner's Manual), hook it up (can be done without removing the battery or disconnecting it) and let it run a full charging session. Might get you out-of-the-woods. But yeah, better start reading, and window-shopping for a battery: it may be too far gone.

    1. How frequently is the car driven, and how long are the trips?
    2. Have you had any battery draining events, says leaving a door ajar overnight, or headlights on?

    * A smart charger is one that assesses the battery when you hook it up, then runs through a series of stages when charging, and finishes up in a maintenance mode, that could be left on near-indefinitely if need be.

    Disconnecting, cleaning and reconnecting both battery terminals is something else you can do. But for starters I'd just ensure connections are tight: gently snug both the positive and negative cable clamp bolts, just a slight turn, and make sure the connections don't budge when you pull on them. Use a small 10 mm wrench, and be careful not to make a "bridge" between neg and pos terminals with anything metal.

    Kinda overkill, maybe not: at least wear safety glasses while working on the battery, face shield even better. I break that rule frequently, but still a good idea.
     
    #4 Mendel Leisk, Oct 1, 2020
    Last edited: Oct 1, 2020
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  5. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    So it looks like I bought the battery the beginning of July.

    Trips vary from 25mi/45 minutes to in town stuff. At least every other day.

    Not sure if the charger is a smart one or not - probably not. I can look when I get home.

    Where it’s parked it can stay running if I get that far, very secluded yard.

    When it happened I didn’t find any light offenders or any else that would have cases the drain. I will check all the connections when I’m back home too.

    I’ll call autozone and figure out what the warranty on it is. At this point they should really just replace it.


    iPhone ?
     
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah the battery could be a dud. Hate to say, but best bet can be dealership, as far as getting "fresh" batteries, and getting 100% compatible.

    If you can pick up something like a Solar BA9 (around $70~80, an electronic load tester), you can assess the prospective purchase battery at the store. That said, many battery retailers now have a pro-version of such a tester on hand, and are willing to test/demonstrate the battery's health, before you take it out the door (or have it installed).

    Phone to verify, about something like that. It's good for both parties, to know upfront the battery's in good shape.
     
  7. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    Sadly the dealership wanted $300+, and then plus a tow. COVID unemployed single mom had other things that needed money. Although, after swapping them we got the labor aspect- espy since we were outside when it was 90 degrees

    Thankfully it’s cooler today so I want have an overheating issue dealing with it.

    I think if the charger won’t do it correctly I’ll just pull it and take it back under warranty.

    This is the battery I bought.

    https://www.autozone.com/batteries-starting-and-charging/battery/optima-battery-46b24r-group-size-46b24r-450-cca/315064_0_0



    iPhone ?
     
  8. NewHybridOwner

    NewHybridOwner Active Member

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    There are many reports that Optima batteries aren't what they used to be. But it's possible that the old battery died because the charging circuit was not up to scratch and that is why the new battery is now dead. I think you should go back to Autozone and have them check both the battery and the charging circuit -- if they did not in fact check the latter when you went there for the new battery.
     
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  9. SFO

    SFO Senior Member

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    If the battery has lasted for 3'ish months, then it could be that you have some bad connection(s).

    If they want to swap it for a newer battery then great, but usually they will want to test and charge before a warranty exchange.
     
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  10. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    The last one didn't die all the way - we had to jump it, but it had been sitting due to a salvage rebuild (drivers rear quarter panel we knocked out but the guys insurance totaled it) falling into COVID closures and we couldn't get it inspected. I was bad about driving it around my yard or up the driveway so we just replaced it. It was over 3 years old and FL battery life is the pits.

    This one is weird to me because it is holding at 10.4ish. The doors unlock, the lights work, the triangle glares at me... lol

    I'm back home, going to see if i can find the 10mm wrench and check the cables.

    This is the battery charger we have, works decent on regular batteries - except when I am the one trying to use it :LOL:

    Oh and no, they didn't do any sort of test on it when i bought it - i guess it was the female shopper thing going on. I have no issues with them testing and charging it - i'd rather that be on them to be honest. And since it is cooler I can manage to get it out I think without activating my issues. I miss my Tomato and driving this Jeep Cherokee is rough because 25 isn't my idea of good mpg - and the boyfriend wants to drive it since his Outlook doesn't have AC :ROFLMAO:

    Thanks for the help so far!
     

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  11. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    I have a bumpy driveway so it very well makes sense something back there might have worked it's way loose.
     
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    You're current charger does NOT look like a smart charger, and I think way too high amperage.

    I looked up CTEK's current offering: they used to have a 3.3 amp version (CTEK 3300), but in short supply now maybe. My current charger is their 4.3 amp, available on Amazon, and a 0.8 amp as well. A little frustrating: I'd like get the 4.3, even though it's amps are a little over the limit, just keep my fingers crossed. :)

    CTEK is definitely not the only option, just my pref, but it's worked out well for me. In these COVID times our car is pretty much always on the charger: I hook it up any day the car is idle, and leave it on till next time the car is used.
     
  13. dolj

    dolj Senior Member

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    The Genuine OEM AGM battery in my car has a label that says to charge at 4 Amp maximum. I don't think 4.3 A is anything to worry about, and it is the maximum that it can charge but as it goes through the stages it will charge at a lower rate, particularly when it reaches the maintenance cycle.

    The 3.5/4 Amp warning is more about "Don't thump this battery with 10 or 15 Amp or more", kind of a thing.

    No need to get all OCD fixating on the amperage rating, as long as it near enough, and to me that 4.3A CTEK would be perfectly near enough.

    A couple of comments on this OP statement,
    • 5 minutes would not be near enough time to make any appreciable difference;
    • any reading of 10/10.5 volts is severely discharged. You should be aiming to keep the battery at between 12.6 V and 13.2 V.
    If your battery is constantly dropping to sub-11 V territory then the battery is faulty or you have a parasitic drain going on. If the latter, you need to investigate and fix or you will be replacing batteries every two to three weeks.
     
    #13 dolj, Oct 1, 2020
    Last edited: Oct 2, 2020
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  14. rjparker

    rjparker Tu Humilde Sirviente

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    1. Have you tried to clear codes by simply disconnecting one lead of the 12v battery for a few minutes then reconnect and test?

    2. If you jumpstart it does the car go into Ready? If it goes to Ready the inverter should supply the 12v at a higher voltage, probably around 14.4v in your case.

    3. If jumped and in Ready does it the run and drive?

    4. Have you found your scan gauge yet to read codes?
     
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  15. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    I just got help with this....

    1. Battery was out overnight - will that clear them?

    2. It won’t jump, I even ran it connected to the outlook for 5 hours and it wouldn’t start (and light switch/info button never went over 12.1) AutoZone replaced that battery under warranty the other day. New one out of the box is only reading q1v. Stupid me did NOT have him check it before I left.

    note, battery compartment had water in it, which might have caused the issue. I tried to seal the areas on the roof and hatch that might be suspect.

    3. It tried to start once while being jumped.

    4. No, which also means I haven’t found my new windshield wipers. They could have ended up at storage. :(

    ‘He’s going to go to auto zone to get it tested, then we will go from there. He’s asking what else it could be - I have no clue how to check for something sucking it dead.

    I miss my car badly...
     
  16. bisco

    bisco cookie crumbler

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    you probably need tech stream.

    how many volts is q1?
     
  17. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    I’ll end up having to have the neighbor tow it to the stupid dealer. Ugh.

    and sadly I have no clue what q1 is, off to try to figure that out.

    auto zone swapped the battery again, they tested it and it is showing 13.4v, and I think he said they load tested it too.
     
  18. bisco

    bisco cookie crumbler

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    13.4 would not be with the car off.:(
     
  19. AlwaysDrivingFL

    AlwaysDrivingFL Junior Member

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    That is with their tester, we haven’t put it in the car yet - it got too dark out and the crap[y porch light doesn’t reach where it’s parked.

    I just seriously need it to start. The fact that it was running fine, I parked after driving home from somewhere (most likely 30- miles) and was totally dead in the morning is what makes it hard. Honestly the only option becomes some animal eating something ;(
     
  20. rjparker

    rjparker Tu Humilde Sirviente

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    He was asking about your typo above where you said the battery was reading "q1v". I assumed you meant 11v since q and 1 are on the same key, at least on ios.

    If it were me, I would get a flashlight and install the battery now. My best guess is your issues started on Oct 1st as a severely discharged battery. Sometimes a badly discharged battery will drag down a jumper cable voltage. But with a fresh battery you should be ok from a voltage standpoint but you can't just put it off.

    I would put it in. If necessary, use the charger on it IN the car overnight if there still is any concern about its charge state. I would do those things now. If it does not go to Ready, try several times.

    Reading codes is the next essential move.

    If still no go and you read no codes (unlikely) then its possible that an inadvertent swap of the jumper cables happened. Could have been on the donor car side. Happens. But if your screen is coming up its not as likely. Sometimes swapped jumpers just blows some fuses.
     
    #20 rjparker, Nov 5, 2020
    Last edited: Nov 5, 2020