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When to Replace 12V Battery

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Siward, Sep 30, 2016.

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  1. xliderider

    xliderider Senior Member

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    There's a bolt on the firewall with another grounding wire on it near the fusebox.
     
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  2. bisco

    bisco cookie crumbler

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    that's what i use. i don't see the need to go to the other side, it's not like your trying to avoid a spark near the battery.
     
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    You can use any bare, grounded metal. For small size clamps, or a multi meter probe, I use location #1. If you're using larger jumper cables that might slip off that, there's a shock tower bolt a bit beyond #2.

    upload_2016-10-1_8-9-0.png

    The outstanding metal tang at right corner of inverter (supporting cable conduit) is also grounded, but I'm a little leery about connecting to it, lol.
     
    #23 Mendel Leisk, Oct 1, 2016
    Last edited: Oct 1, 2016
  4. xliderider

    xliderider Senior Member

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    Yes, avoid using the inverter cover bolts as ground. I've had check hybrid system errors for unexpected ground detected in the past. The error clears, but best to avoid them in the first place.
     
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  5. Bluegrassman

    Bluegrassman Active Member

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    Thank you for the pic and the info!

    Posted via the PriusChat mobile app.
     
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  6. CR94

    CR94 Senior Member

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    Being low, shaded, and dense, that battery won't get nearly as hot on a sunny, hot day as the interior does---or as hot as an under-hood battery does in other circumstances.
     
  7. bisco

    bisco cookie crumbler

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    i still think draining it is the biggest issue.
     
  8. Michael Wood

    Michael Wood Active Member

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    My 2015 Prius has 110k miles. The 12v battery just died almost 4 years to the day since I bought the car. No warning - went out to get in the car and it was dark - dead. I replaced the factory battery with the Bosch Group 51 AGM for Prius at PepBoys $146 after 25% online discount. I don't live in a warm climate so getting only 4 years out of the original battery surprised me.

    Note - I had no problems with the posts on the Bosch battery and the clamps on my gen3 Prius.
     
  9. bobzchemist

    bobzchemist Active Member

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    And that's exactly the reason for replacing the battery every four years. Sometimes it just dies without warning. Could you stretch it to 5,6, even 7 years? Maybe, maybe not.

    But if you think of it as a regular maintenance cost, like an oil change, then you'll be in a position to jump on a deal like the Bosch at PepBoys without having to worry about being stranded somewhere in the middle of nowhere and paying whatever the 24-hour repair shop feels like gouging you for. At $150, the PepBoys battery works out to roughly $38 per year on a four year replacement schedule. If you try to stretch the replacement out to 6 years, you can drop the cost down to $25/year. Is saving $13/year worth buying car starting booster packs and making sure to keep them charged worth it?
     
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  10. Siward

    Siward Active Member

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    Batteries come with pro-rated warranties. You can get a discount if you wait until it dies although it would be pretty troublesome to deal with it. You can't use the warranty if you replace it early unless it tests at a low voltage.

    I don't mind dealing with dead batteries in the summer, but I would really hate being stranded in the winter. That being said, I replaced my OEM battery after 4 years to be safe.
    Canadian Tire Eliminator Ultra AGM Battery for Prius (w/Pics) | PriusChat
     
  11. VictorB

    VictorB New Member

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    Good Information
     
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  12. NewHybridOwner

    NewHybridOwner Active Member

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    The original battery on our '02 Chrysler -- a regular maintenance-free wet-cell battery -- was more than 7 years old when I replaced it just because...
     
  13. bisco

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    had the battery ever been drained inadvertently during the 4 years?

    i've never gotten less than 8 years from the oem
     
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  14. Siward

    Siward Active Member

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    There are so many factors that determine battery life. It is hard to predict. Someone I know recently left his car undriven for 3 months and the battery got drained.
     
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  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Protracted down time is tough on 12 volt batteries, there's constant low level drainage.

    Ours often sits for multiple days, and now spends more time hooked up to a CTEK 4.3 charger than not. I've wired in the quck-connect, makes it easy. Coming up on 4 years now, still in the pink.
     
  16. bobzchemist

    bobzchemist Active Member

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    I think @Mendel Leisk brings up a good point.

    If you take care of your battery and keep it charged with a quality de-sulfating charger, it will last longer. If you are careful, and never run your battery charge to zero, it will last longer. If you protect your battery from extremely hot temperatures, it will last longer.

    If, on the other hand, you are someone like me, who forgets sometimes to turn off headlights, and who lives in Atlanta, and who rarely remembers to hook the battery up to a charger, then you might want to use a more frequent replacement schedule.

    The big thing to remember is that these batteries can fail without any warning. It's all risk management - how much is it worth to you to go out to your car and have a 100% certainty that it will start when you push the ignition switch? If that's worth a lot, then it makes sense to replace your battery frequently. Could the battery last longer? Probably. But the chances of failure go up with every year of use.
     
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  17. Robert Holt

    Robert Holt Senior Member

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    We have left our 2012 Gen 3 hatchback parked for up to 2 months at a time, but we were very careful to unplug the Scangauge and use the vehicle setup menu to turn off the SKS and remote door lock systems. Startup requires re-entry with the physical key and putting the key fob right up to the power button for a restart. The 12-volt survived but it appeared to be getting weak after doing this several times over 4 years, so I proactively replaced it.

    On our Gen 3, I have used the setup menu to set the auto-lights-off function to turn off the lights immediately at shutdown.
    (Small Aircraft ICEs are sparked by dual magnetos to avoid plane engine failure due to 12-volt battery failure. However, the interior lights and the electrically-driven subset of instruments plus the radios die when the 12-volt dies, so flying becomes high stress, particularly if it occurs at night. I carried a small red lens flashlight to hold in my mouth and a backup radio to cope with this situation.)
     
  18. Mendel Leisk

    Mendel Leisk Senior Member

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    On our 3rd gen I measured milliamps with the car off, it was around 18, with spikes maybe every 5~6 seconds to around 40. I don't think the spikes were the security icon on the dash: it seemed a little more frequent. Not sure though. It would seem a likely suspect.
     
  19. bisco

    bisco cookie crumbler

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    i leave my car sitting 8-10 weeks every winter in an unheated attached garage, no problem.

    when people in cooler climates say they only get 4 years out of a 12v, you have to wonder if something else is going on.
     
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  20. Michael Wood

    Michael Wood Active Member

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    No....this was the first problem of any kind we've ever had with the car. The 2015 Prius has been 100% flawless.

    For other owners who are near or beyond the 4 year mark on the OEM 12v battery, I would recommend investing $30 in a Battery Tender. It's super easy to connect one at the fuse box under the hood, and you'll accomplish 2 goals. Your 12v battery will always be at full charge, and you'll see the increase in recharge times if/when you start to see some degradation. It may save you a major inconvenience.
     
    #40 Michael Wood, Jun 30, 2019
    Last edited: Jun 30, 2019
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