12v battery jumping and replacement options

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by srivenkat, Sep 1, 2020.

  1. srivenkat

    srivenkat Active Member

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    Hi All,

    My car sat on the dealer lot for ~5 months, so I would like to prepare for the eventuality of a dead battery. I wonder if the battery is covered under the 3-year/36K warranty. Also wondering what the latest consensus is for a good after-market replacement (since the Toyota ones are usually more expensive).

    Also, I would be grateful for any advice on using a portable LiIon jumpstarter if need be.

    Thanks.
     
  2. Salamander_King

    Salamander_King Senior Member

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    Have you checked the resting voltage of the 12v battery? I am sure if you find your 12v battery dead within 3 years, then you can demand it to be replaced under general warranty, but they may ask you how often the car was driven or the battery was charged. Hard to believe that by just sitting on a dealer's lot for 5 months the battery dies prematurely, but I have read enough threads here on both Gen4 and PRIME 12v battery early demises, so I am being proactive and monitoring my 2020 PRIME's 12v battery SoC very closely using Bluetooth Battery Monitor and not letting it go under 12.4v. Replacement aftermarket H4 or L1 or 140R BCI group size (8.1" x 6.9" x 7.5") 12v batteries are now readily available and cost about $100~$160. But OEM battery is not that expensive ~$180 last I checked. When it's time for me to buy a new 12v battery, if that day ever comes, I plan to negotiate with a local Toyota dealer to install a battery for $99 as advertised on their web site service coupon.

    As for the jump starter, I bought DBPOWER 2000A 20800mAh Portable Car Jump Starter last year, but have not used it yet. For Prius, you do not need a huge cranking power, so even a very small lithium jump pack will do the job. I think you may also want a good smart battery charger/maintainer if you are worried about the 12v battery health status. Many people suggest CTEK chargers, but I ended up buying Bluetooth enabled Victron Blue Smart IP65 charger. Blue Smart IP65 Charger (120V and 230V) - Victron Energy
     
    #2 Salamander_King, Sep 1, 2020
    Last edited: Sep 1, 2020
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  3. srivenkat

    srivenkat Active Member

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    Thanks for the info. Here are some measurements:

    Last night, a couple of hours after an hour long drive: 12.75/76
    This morning after NOT plugging-in overnight: 12.45/46
    After going for a 15 minuted EV drive this morning: 12.45/46
    Car plugged-in right after this, while charging HV battery: 12.65/66

    It looks like Toyota is assuming one will keep the car plugged-in at home? Also, this battery doesn't look like AGM; perhaps a deep-cycle AGM would have been better for the application? (Disclaimer: not a battery expert; amateur thoughts).

    I might try and repeat the auto-shutoff experiment I did with my Gen III:
    12V battery low-voltage auto-disconnect | PriusChat

    I might be able to get the disconnect switch programmed to disconnect at a lower voltage. Or the easier option might be to just keep a jumpstarter battery.
     
  4. Salamander_King

    Salamander_King Senior Member

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    Charging the traction battery does not charge the 12v battery substantially. It only maintains at voltage around 12.5v, and this happens only during the time the traction battery is actively being charged.

    No, it is not AGM. It is a regular flooded lead-acid battery. The OEM battery is not even sealed. It has vent caps on it. That's why replacement battery should not cost as much as for the older Prius with AGM. I have read pros and cons of AGM. Although some people believe it is better, AFAIK for now finding an AGM battery in the size required to fit Gen4 Prius or Prime is difficult.

    Your battery voltage reading looks very normal of a healthy 12v battery. You may want to follow this thread to see what others are seeing. There are some 2-3 years old 12v batteries in the Prime which seems to have lost capacity especially now with COVID-19 restriction and less driving.
    12v Battery Is Discharging, Re-Charge Now ! | PriusChat
     
    #4 Salamander_King, Sep 2, 2020
    Last edited: Sep 2, 2020
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  5. FuelMiser

    FuelMiser Senior Member

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    There is a lot of discussion on 12V replacement in the Gen 4 Prius Hybrid section (not Prime). They have the same 12V battery...
     
  6. jerrymildred

    jerrymildred Senior Member

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    Just the opposite.

    Screen Shot 2020-09-02 at 10.30.23 AM.png
     
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  7. srivenkat

    srivenkat Active Member

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    Thanks for pointing that out, Jerry. Wish Toyota had trickle-charged the 12V from the wall-connection, before and after the HV battery charge event. Perhaps they have some genuine reasons to not have done that.
     
  8. bisco

    bisco cookie crumbler

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    a lot of people agree with you. see @Rob43 's thread on 12v draining per day
     
  9. jerrymildred

    jerrymildred Senior Member

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    To do that would have required connecting the traction battery to the inverter the whole time it's plugged in. I suspect there are safety as well as energy efficiency reasons for not doing that. Plus, it would be a pretty sad day to wake up one day and find that your unnecessarily plugged in Prime got fried by a lightning strike. It could still happen, but it's less likely if you're not connected to the wall all the time. In fact, I went outside in the rain a few minutes ago to unplug mine because there was lightning in the area.
     
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  10. srivenkat

    srivenkat Active Member

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    I used to have a CTEK that I can't find now. IIRC, the CTEK had to go thru the charging stages (including desulphation?) before going into "float" which I assume is what trickle-charging/battery-tending means. Does the IP65 have the ability to just do battery-tending (without everytime trying to desulphate and such)?
     
  11. Salamander_King

    Salamander_King Senior Member

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    Not out of the box, but I think it can be custom programmed using an app to be just battery-tending voltage. But my understanding is that if you use a smart charger like CTEK, going through the normal charge cycle does not harm the battery. On my Victron charger, there is mode selection to include "reconditioning". The manual does suggest not to overuse the "reconditioning" mode. I am not sure if CTEK charger has the selection of the mode, but if it harms the battery to be used all the time, I would think it has a way to not use it. If you simply want a battery maintainer, there are other less expensive ones, but I have read cheap ones like $5 HF battery tender is set to just the very low constant voltage and it may overcharge the battery over time. So, again it may be wise to invest in a charger that does control the charge level according to the battery level.

    I hope others more knowledgeable than me will chime in on this topic.
     
    #11 Salamander_King, Sep 2, 2020
    Last edited: Sep 2, 2020
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  12. srivenkat

    srivenkat Active Member

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    Also, my 2007 Camry Hybrid (in-service Fall 2006 with SKS) is still on the original 12V battery. One thing I always do is to switch off all the electricals and take my foot off the brake pedal (after gear in P) before switching off the car. I also normally leave the cabin light to OFF (as opposed to DOOR), for fear a door ajar might cause a drain.
     
    #12 srivenkat, Sep 2, 2020
    Last edited: Sep 3, 2020
  13. srivenkat

    srivenkat Active Member

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    Thanks for the info. Do you have to pop-open the hood to get to the charging cable connection or do you connect thru the front grille with a cable extension connector of some sort?
     
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  14. Salamander_King

    Salamander_King Senior Member

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    I have been doing with the hood open. It is not too much work, but as a part of mod project on the front grille cover I am working on right now, I am planing to install exactly what you are describing. A on board battery charger will be housed under hood and connected to the 12v battery post permanently, then charger cord will be attached to a cable extension with a male plug in hidden behind the license plate. This will be easier to connect and recharge the battery with just a plug-in an extension cord from any power outlet. I will report more when I have the project finished. At this point, I only have the parts ready but have not done any of modification yet.
     
  15. srivenkat

    srivenkat Active Member

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    The CTEK I had came with the below cord (attached photo); I think they call it the "comfort connection". I believe they sell longer versions of these that could probably be routed thru the front grill. But one would have to use the specific compatible charger (CTEK in this case) to connect.

    Also, I see Battery Tender (and NOCO also?) have a OBD connector for charging via a solar panel, which might work if the car is outside on most/many days. Perhaps the OBD route would be easier and probably safer?
     

    Attached Files:

  16. srivenkat

    srivenkat Active Member

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    NOCO has this one:
     
  17. Salamander_King

    Salamander_King Senior Member

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    I have never heard of OBD connection to charge the 12V battery. But, since there is OBD connector to supply 12v power to the car during on-board 12v battery removal (to save all the memory and prevent re-initializing the car), I guess, you can charge the on-board 12v battery via OBDII. But, I have no idea how that works or how safe it is. @Rob43 has a DIY solar panel connected to his 12V battery but I don't think it goes through the OBDII port.
     
  18. srivenkat

    srivenkat Active Member

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    Yes, I saw what @Rob43 did and subsequently saw the below combo (OBD+Solar-panel) that BatteryTender makes:


    Not sure if the Battery Tender trickle charger can be connected to the above OBD cord, but NOCO does seem to have such a combo available: NOCO - X-Connect OBDII Connector - GC012

    IMHO, this might be a safer approach than going thru the grill (which might expose it to the elements, affect crash-safety, etc).

    Plus it could be routed thru the steering wheel, so can't be inadvertently missed.
     
  19. srivenkat

    srivenkat Active Member

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    Also, I am curious if anyone has reported any abnormal negative consequences of a battery going dead.
     
  20. Salamander_King

    Salamander_King Senior Member

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    I don't know about the safety. Connecting a charger to the 12v battery under the hood is just as safe IMHO. One problem of using OBDII connection to charge the 12v battery is that you will have to connect your charger/tender and to the wall 120v power source, so the cord has to be going out of the car from cracked window. With under hood connection, even without special connection cord or on-board charger, you can keep the charger under the hood and feed the cord through the grille and close the hood securely. However, since I don't have problem with security, so I just keep the hood popped open when I charge my car.
     
    #20 Salamander_King, Sep 3, 2020
    Last edited: Sep 3, 2020
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