Does 12v battery charge when charging PIP

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by electrode, May 21, 2015.

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  1. electrode

    electrode Junior Member

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    I was wondering if PIP really does charge the 12V battery along with the traction battery when plugged in. A couple of posts on the internet (including on here), suggests it does, but there is no mention about it in Prius manual (including the emergency response guide http://www.evsafetytraining.org/~/media/electric%20vehicle/files/pdfs/toyota/toyota%20prius%20phev%20%202012.pdf).

    Did anybody confirm if the 12 volt battery really charges when plugged in? The reason I ask is that my commute profile changed significantly from when I decided to buy the PIP to when I bought the PIP, so I am no longer doing long enough runs that allows battery to charge (< 5 miles per trip one way), apartment dweller (i.e. no nightly charging) and random availability of charging at work (couple times a week). I guess that even if in EV mode, the inverter will charge the battery, but not sure if the <5 miles trips are enough to charge the battery.
     
    #1 electrode, May 21, 2015
  2. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    The 12V battery can be charged whenever the the car is in READY mode (and I think also when being externally charged). There is very little demand on the 12v battery in a Prius (plug-in or standard); pretty much all it has to do is boot up the hybrid control computer. While the car is running (in READY mode), the hybrid system provides 12v power as required. The hybrid control computer monitors the charge level in the 12v battery, and keeps it charged appropriately.

    If the gasoline engine needs to be started, that is done with the large hybrid battery. This is very different from a conventional gasoline automobile, where the 12v battery needs to send a lot of power to a starter, which starts the gasoline engine, and the engine has to run a while turning the alternator to restore the power used to start the engine. There is nothing comparable in the Prius. The 12v battery in a Prius looks like a motorcycle battery.
     
    #2 CharlesH, May 21, 2015
    Last edited: May 21, 2015
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  3. rxlawdude

    rxlawdude Active Member

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    My understanding is that charging of the 12v battery occurs while the HV battery is being charged.
    BUT, leaving it plugged in after the HV charging is complete does NOT continue to charge the 12v battery. In other words, it doesn't do "battery minder" or "trickle charging" for long-term storage.
     
    #3 rxlawdude, May 21, 2015
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Take a digital volt meter reading on the 12 volt battery, before and after plug-in charging.
     
    #4 Mendel Leisk, May 21, 2015
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  5. bisco

    bisco cookie crumbler

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    just because you can't find it in the manual, doesn't mean it's not there. that being said, i don't know where the info comes from.
     
    #5 bisco, May 21, 2015
  6. giora

    giora Senior Member

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    Before, during and after is even better.
    And yes, the auxiliary battery is being charged when externally charging, easiest way to see it is leaving dome light on and then start charging - light becomes brighter.
     
    #6 giora, May 22, 2015
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  7. electrode

    electrode Junior Member

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    Thanks for all the replies. I don't have a multi-meter, and after buying a litany of tools that I used only once, my SO will kill me for adding another tool to that collection. Checking the light brightness seems like a nice idea.

    Now the story behind the question -- There was a workplace discussion thread talking about charging etiquette, and someone mentioned that given that every car comes with SMS notification (or something similar), people should be moving their cars once the cars are charged, and I am like, not every car has that feature. It led to me think (seeing all the cool mods here) whether we could build an after market solution.

    -- Lycamobile hotspot with free data plan
    -- A Raspberry PI (or similar).
    -- a couple relays to power the PI, as well as to determine when the charging has completed.

    For less than $100 in parts I am thinking we can build our our notification for the base prius (or even advanced prius that no longer subscribes to the monthly plan).

    To get more advanced, we could possibly control the AC (will it be possible with the OBD2 port?) remotely, and also decide when to charge (and to be really inconsiderate, the mod would keep the charging light on, even after charging has completed), and if using OBD2 link possibly see the current battery status (as it charges).

    Of course, my middle name is "not brave", it is unlikely I am going to do the mod on my own, but I can dream can't I?

    There is where I get the "inspiration" for the advanced options
    photo 10.PNG
     
    #7 electrode, May 22, 2015
  8. bisco

    bisco cookie crumbler

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    by the ev estimate you have left when you plug in, you pretty much know when to move your car.

    for example, i'm charging to 15+ right now, so if i drive to an L2 charger and have 5 miles left, i need about 45 minutes to recharge. it's not perfect, but close enough for etiquette. heck, anyone with a bev is going to tell you you shouldn't be hogging the spot in the first place.:rolleyes:
     
    #8 bisco, May 22, 2015
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  9. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    Right; many BEV owners feel that charging stations should be reserved only for plug-in cars that do not also have a gasoline engine. They feel that since they HAVE to charge, they should get priority. We Volt and PiP owners can just use gasoline.

    So they feel.
     
    #9 CharlesH, May 22, 2015
  10. ft3sfty

    ft3sfty Junior Member

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    YES, my 2015 Plug in Prius's 12V battery in the trunk charges while plugged in! My volt meter reads 13.58 Volts while plugged in and the car is off. Not the typical 14+ volts from a regular battery charger but I'm assuming my 12V battery is full. After all my car has less than 1500 miles on it. While the car is off and not plugged in, the battery shows around 12.6 volts.
     
    #10 ft3sfty, May 22, 2015
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  11. electrode

    electrode Junior Member

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    That line of argument did not get too far at my work place. If BEV owners feel they "have" to charge, that should happen in the confines of their own home. The PHEVs can run on electricity too (and the owners may be living within the range of PHEV capacity), it was decided that everybody has the same claim to mooch off of free charging spaces (or even paid ones, although for PIP it doesn't make sense to charge in commercial chargers).
     
    #11 electrode, May 22, 2015
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Just patiently explain: when you're done with the car you can check the drawer full of old AA batteries. But you'll NEED the high end meter for that. :whistle:
     
    #12 Mendel Leisk, May 22, 2015
  13. electrode

    electrode Junior Member

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    Turns out OBD2 port is inactive unless the car is in READY mode, so that rules out reading the data while charging, and therefore all the ideas I had (remotely turn on A/C etc) will not work. I guess the vehicle interface modules (which requires on FOB to be installed in the module will probably not work due to SKS complaining about key still in the car
     
    #13 electrode, May 23, 2015
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    I do know for sure the 12 volt pins in the port are active when the car is off. But maybe that's all, not at all sure.

    I use an OBDII cord with just the power pins, as memory saver when disconnecting the 12 volt.
     
    #14 Mendel Leisk, May 23, 2015
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  15. electrode

    electrode Junior Member

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    Yes, the power is always present on the power pin (elms with led always stay lighted), but I think you can't query the system.
     
    #15 electrode, May 23, 2015
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  16. bisco

    bisco cookie crumbler

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    dang.
     
    #16 bisco, Jun 8, 2015
  17. LesliePIP2013

    LesliePIP2013 Junior Member

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    Has anyone tried charging their 12V battery? Mine is over 4 years old and will probably need to be replaced soon b/c I've had to jump start it a few times lately. I've seen people mention they've charged them- but they are deep in the bowels of the car, so not easy to get to, and not sure if it is safe to charge where you jump start under the hood.
    I called the Toyota dealer and they said don't try to charge it b/c could cause alot of damage. (?)
    Any experienced PIP owners know?
    thanks!
     
    #17 LesliePIP2013, Apr 27, 2017
  18. Mendel Leisk

    Mendel Leisk Senior Member

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    No problems. Use a decent quality, up to date smart charger, around 3-4 amp. Watch you get the clamps right way round, at under hood jump point fine. That said:

    If you've been jump starting multiple times it may be not worth it. But get it checked out wit a digital load tester, go from there.
     
    #18 Mendel Leisk, Apr 27, 2017
  19. giora

    giora Senior Member

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    Remember that the PiP 12V battery is being charged-up every time you charge the traction battery from external source. So, if you do charge your car regularly and still had to jump-start it several times now - it seems the 12V battery is at the end of its life, time to replace it.
     
    #19 giora, Apr 27, 2017
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  20. LesliePIP2013

    LesliePIP2013 Junior Member

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    Thanks, I think you are right. Its so expensive to replace so trying to make it last as long as possible!
     
    #20 LesliePIP2013, Apr 30, 2017
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