Battery and power usage

Discussion in 'Clarity' started by iluvscuba, Apr 1, 2018.

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  1. iluvscuba

    iluvscuba Active Member

    I just saw a video of the Hyundai Ioniq EV cannot start the car when the 12V battery is drained (or below a certain voltage theshold). Apparently, the big battery will charge the 12V battery only when the car is in the 'ON' mode but not in Accessory mode so if you are sitting in the car and listening to the radio with the seat warmer on while in Accessory mode only, it is possible to drain the 12V battery.

    First question, will the Clarity start if the 12V battery is drained or say in a few years when the 12V battery is getting old and if the winter temp is -30C (or whatever)?

    So my question for the Clarity is which electronic gadget in the Clarity uses the 12V battery and which uses the big battery?

    1. Power Window and power mirror
    2. Power Door lock
    3. Entertainment System
    4. The driver front LED screen
    5. The middle 8" screen
    6. Heated front seat
    7. Rear window defrost
    8. Heater and A/C
    9. Electronic handbrake
    10. Electronic brake hold
    11. Auto dimming rear view mirror
    12. Electronic shifter
    13. Moving the car (pretty sure this uses the big battery)
    14. Windshield wiper
    15. All the lights (headlight, high beam, tail light, cabin light etc)

    Anything else I am missing?

    If you are waiting around in the parking lot, do you use Accessory mode (Press Start button without pressing the brake paddle) or do you always have the car in ON mode?
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  3. M.M.

    M.M. Active Member

    Have a look at the fuse list on page 554-559 of the manual--that tells you absolutely everything that's on the 12V system.

    Which is to say virtually everything on your list.

    Based on the fuses in the manual, I'm pretty sure the only things on your list that don't use the 12V system are the main heater and moving the car--certainly all the electronics, and I see the seat heaters, A/C and the cabin heat motor in there. The actual heater isn't, which makes sense--I know the heater in a Volt draws 5kW or more, and the Clarity is at least that, so there's no way the 12V system can handle it.

    All the smaller motors, auxiliary stuff, cabin stuff, lighting, electronics, etc are 12V, though.
    Louis Nisenbaum likes this.
  4. M.M.

    M.M. Active Member

    I just realized I didn't answer the first part of your question: No, the vehicle will not start if the 12V battery is dead. This is (presumably) because the control electronics all run at 12V, and you need to power those up in order to turn the car on, and you need to turn the car on in order for the DC-DC converter to start providing 12V power off of the high voltage battery pack.

    This is why there is a jump start procedure on page 539 of the manual. Unlike a regular vehicle--where the jumping vehicle needs to provide enough power to get the engine to crank (which is a lot) so the alternator will start producing 12V power--I would assume that all you need to do in a Clarity is provide enough power to get the computer to come on so you can press the start button. Once that happens, the high voltage pack will start charging the 12V battery and you're good to go. You could probably jump start it with just about anything that can provide a couple of amps at 12V.

    Sitting around in accessory mode for long enough will presumably run down the 12V battery, although it's possible the car will try to shut itself down at some point to leave enough power to get going.
    iluvscuba likes this.
  5. iluvscuba

    iluvscuba Active Member

    What is the difference between the On mode and Accessory mode? In an ICE car, obviously the On mode will consume gas as it will start the engine but in the Clarity, if the only thing that On mode has over Accessory is for moving/driving the car, then there is really no difference between using the 2 modes (if not driving) other than On mode will continuously charge the 12V battery whereas the Accessory mode will not, am I getting this right?

    And if so, is there any advantages to using the Accessory mode at all since you might drain the battery thus preventing you from starting your car?
  6. vick

    vick New Member

    Does anyone know what dash cams would be suitable (front and rear) if I want the "parking mode" feature to be on and record when it detects movement or impact? It would be connected to the usb but wouldn't that drain the battery?
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  8. bpratt

    bpratt Active Member

    You're probably right. Makes sense to me. But the heater and AC could run in On mode.
  9. iluvscuba

    iluvscuba Active Member

    There are quite a number of youtube video you can check out for this topic. Most people that want parking mode will plug the dash cam directly into the fuse box instead of the USB/12V socket as power is usually cut off when the car is off (I don't know what the Clarity behavior is). Just search for 'install dash cam for parking mode' in youtube and you will see quite a few videos describing what you need to get that function. Of course it will start draining the battery but there are devices that will monitor battery power and will shut off the dash cam at certain voltage level
  10. vick

    vick New Member

    Would it void my warranty in any way if I DIY and install it myself?
  11. M.M.

    M.M. Active Member

    Yes, this is correct, and I was messing with the 12V battery anyway so I just confirmed to be absolutely sure. In ACC mode, all power is coming from the 12V lead-acid battery, which will run down eventually. In On mode, the high voltage system (either the battery pack or ICE/generator) is charging/floating the 12V battery, so you're not pulling any power out of it.

    As bpratt noted, ACC mode will prevent you from running things with too high of a power draw--climate control is disabled, the seat heaters won't turn on, the rear window defroster won't turn on, and you can't run the windshield wipers. It's pretty much just the entertainment system, 12V sockets, and USB ports.

    I've been figuring out where to plug a dashcam in myself (I'm really annoyed that the Clarity doesn't have a 12V port or USB port up on top of the dashboard like in some cars). Either the 12V socket under the transmission buttons or one of the USB ports down there would be your best bet, as all three ports turn off and on with the car (they'll be on in ACC mode, but that doesn't really matter). Most (I assume all?) dashcams are set up to turn on and off using power as a signal. Routing the cable will be a pain, though.

    The alternative (which I'd been considering) would be to find an empty fuse slot that operates the same (turns on with the car), and attach a fused wire to that spot, but that's going to be kind of a pain.

    There would be no noticeable battery impact in either of those options, since the port is off when the car is off (dashcams that have parking features usually operate off an internal battery for that).
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  13. iluvscuba

    iluvscuba Active Member

    Not sure about that. But another thing you can do is to use a portable battery charger (like the type where you can charge up your phone) so when you park your car, unplug the dash cam from your car's 12V socket and plug the USB plug into your battery charger. Depending on how big your battery is and how cold the outside temp is, you can probably get an hour or 2 of usage out of it. Of course you should test it and find out how much time your battery will give you base on your dash cam

    Check out this video:
    Last edited: Apr 1, 2018
  14. Neil

    Neil New Member

    It seems like you're more knowledgeable about this than me, just wondering how did you know that all the systems listed in the manual in those pages run on the 12V battery? I just see a list of where fuses are but why does there being a fuse mean it's the 12V battery?
  15. KentuckyKen

    KentuckyKen Well-Known Member

    I got tired of standing on my head to find a place to put an add a fuse and gave up. My back just too much.
    Fortunately my Rexking dual camera has a very nice cigarette plug power source that has a a flip top with a USB port. So now I have an extra USB port which is handy when several passengers are in the car.
  16. M.M.

    M.M. Active Member

    Technically the manual does not specify that those are all 12V devices, and I haven't bothered to put a meter on them, but it's pretty much guaranteed they're all 12V:

    1) Most of the electrical stuff outside the drivetrain aren't custom exotic components designed only for an EV, so will run on 12VDC like any other vehicle. The heater is the one exception.
    2) They look like standard 12V automotive fuses, and they're certainly not high-voltage DC fuses.
    3) The car has a standard 12V battery supplied by a large DC-DC converter, and a high voltage (probably 300V at least) EV battery, but it would need additional DC-DC converters to supply any additional voltage busses, which would only be used if there was a good reason for it. There's a small 5V one for the USB ports, but I doubt there's anything intermediate.
    4) With the amp ratings on those fuses they pretty much have to be at around 12V or the power output wouldn't make sense.

    So while I suppose it's possible there's some intermediate or lower voltage bus mixed in there, it's not likely. One could of course get a more accurate estimate of actual current draws (rather than fuse ratings) by using a clamp-on ammeter to measure actual current.
  17. BobS

    BobS Active Member

    Does the ICE have a 12 volt alternator to charge the battery. Or is the 12v battery only charged ftom the DC to DC converter?

    I see little need for a 12 volt alternator.
  18. M.M.

    M.M. Active Member

    I can't say this absolutely definitively, but I'm nearly certain that the ICE only drives a generator connected to the high voltage bus or a mechanical linkage to the wheels. 12V power is supplied to the 12V battery and its bus by a DC-DC converter fed off the high-voltage bus. Someone in a different thread here identified that it's capable of putting out 2.3kW (around 180-200A @12V), which is equivalent to a fairly powerful car alternator.

    Because the DC-DC converter pulls off the high voltage bus, it doesn't matter whether the ICE is running or not. I've tested and it has no problem floating the battery under heavy load without the ICE running. Interestingly, though, I've noticed in testing that it does not just hold the 12V battery at a high voltage--it will cycle up and down so that the 12V battery is loaded down periodically, and generally seems to cycle between 11.9V and 12.5V most of the time. This is almost certainly for battery health. It will also periodically float the battery to ~14.4V, although I don't know what the schedule is.
    BobS likes this.
  19. insightman

    insightman Well-Known Member Subscriber

    The 12v battery is charged only by the DC-to-DC converter, as with all Honda hybrids beginning with the Insight.
  20. Clarity Dave

    Clarity Dave Member

    A blown fuse or empty fuse position will have the full voltage across it. 12V is OK, but 300V is lethal (especially 300V DC), so routing the high voltage through any of the fuses would be an unacceptable safety hazard.
    insightman likes this.
  21. rickyrsx

    rickyrsx Active Member

    Maybe this can help?

    Fuse map, and which positions are switched vs always on

    Sent from my iPhone using Inside EVs

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