12v Battery Is Discharging, Re-Charge Now !

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by Rob43, Apr 18, 2020.

  1. Salamander_King

    Salamander_King Senior Member

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    Did it change in the 2020 model? I never turned off SKS on my 2017 PRIME, but yeah, I also remember reading somewhere SKS can be turn off by operator without Techstream or Carista.
     
  2. bisco

    bisco cookie crumbler

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    very possible. maybe too many people were turning it off, then going to the dealer complaining that it didn't work :rolleyes:
     
  3. Salamander_King

    Salamander_King Senior Member

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    OK, I received the 5.0000v voltage standard with +/- 0.01% accuracy from voltagestandard.com. This was the least expensive module they sell but still cost $31 + shipping far exceeding what I spent on the cheap Craftsman 82141 multimeter (can be had ~$20). With this standard, I tested all of the cheap multimeters I had. As turned out very cheap $6 multimeter I recently purchased online was closer to the real voltage reading at 5.01v, but my good old Craftsman 82141 was reading at 4.92v off -0.08v. The Craftsman 82141 multimeter actually could be calibrated by opening the case and adjusting a single potentiometer on the board (circled by red in the middle pic below). I was able to bring it to the spot on 5.00v reading.

    The reading comparison of pre-calibration Craftsman 82141 multimeter was ~0.1v lower than the reading I was getting from the BMII, thus the value I have been reporting was just a bit more than actual voltage about +0.02v. This is probably an acceptable margin of error for reading 12V battery SOC.

    screenshot-photos.google.com-2020.05.04-19_31_53.png
     
  4. Bill Norton

    Bill Norton Senior Member

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    Did it come with a statement of Conformity and Traceability back to the National Standards?
    Or is it a china made dealio?
    Seems like a lot of bother for ~80mV difference.
     
  5. Salamander_King

    Salamander_King Senior Member

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    I don't know what standard is used, but it came with a certificate. Not from China. You can read his equipments and all the specs here if you want. Yeah, I already knew the discrepancy was about 0.1v between three different devices, but without a known standard, I could not be sure which one is the closest to the real value. I am sure it was cheaper than buying a Fluke multimeter or sending out the $20 multimeter for calibration. Your donuts suggestion would have been cheaper, but not easier in the present lock-down situation.

    IMG_20200504_183517.jpg
     
  6. Bill Norton

    Bill Norton Senior Member

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    Only no data on your important 12-14 VDC range....;)

    True about trying to reference a new-ish Fluke.
    I could see you ask the tech to go read that battery and then leave, then you write down all the readings you get on your multimeters.

    But even that feels like a lot to ask at this time.

    And who wants breathed on donuts?:whistle:

    I've read that the only safe food to go is hot food which you can then reheat when you get it home.
    We have been really upping our home cooking! I don't crave any to go foods!:)
     
    #186 Bill Norton, May 5, 2020
    Last edited: May 5, 2020
  7. Salamander_King

    Salamander_King Senior Member

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    Yeah, there is a .0025% 10V Reference they sell which is better suited for 12v reference, but it cost $65+shipping. That gets too expensive for my liking. From what I needed to know which three devices I used to measure my 12v battery initially are the closest to the true value, I think 5v standard is enough. Also, I saw in YouTube video that those cheap multimeters when it is off, it is off on all of the ranges in linear increments. So, if it is off 0.08v at 5v, it is likely to be off 0.16v at 10v or 0.192v at 12v.
     
  8. Salamander_King

    Salamander_King Senior Member

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    This is the third week after fully charging the 12v battery with a smart charger. The car was driven once a week for ~1 hour. Each week, the onboard charge system during drive would replenish 12v battery back up but not to full above 100%. This week, after the drive the 12v SOC was at 12.65v, and then dropped after that to 12.54v (day1), 12.46v (day2), 12.4v(day3), and today 12.37v(day4). The pic was from yesterday.

    I am going to plug-in the car today to see if that would bring the 12v SOC back to near 100%. If not, I will charge the battery with a smart charger.

    Screenshot 2020-05-05 at 7.57.11 AM.png
     
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  9. Hicksite

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    Very useful information, thanks! Your results closely correlate with what I have observed. I'm anxious to see if the results you get when you charge the traction battery have an effect on the 12 volt similar to what I observed.
     
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  10. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Good work. I've very interested to see this result.

    I ordered a BM2 like yours and am waiting on the slow boat from China delivery.:rolleyes: Since this thread began, I've been trying to track down a parasitic power draw on my 4Runner. I've been measuring voltage every hour while making changes, etc., then more testing. etc. The BM2 will make this a lot easier. Parasitic draw detection is not simple, but it's a whole lot easier than on a hybrid that keeps reshuffling the deck when you're not watching. ;)
     
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  11. Salamander_King

    Salamander_King Senior Member

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    Yeah, the great thing about Bluetooth BM2 is you can monitor the battery SOC 24/7 remotely without the fuss of keeping the hood open and connecting voltmeter for static value at the time of reading.

    So, I am now a little over 2 hours into the EVSE charging, the 12v SOC is now up to 12.62v 99% from this morning low of 12.37v 60%. As soon as I plugged in the EVSE, the 12v SOC went up to 12.55v. The bottom is the graph as of 2.5 hours after the start of charging.

    Screenshot 2020-05-06 at 12.27.01 PM.png
    screenshot-photos.google.com-2020.05.06-12_27_31.png
     
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  12. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Finally, actual proof of what we've all wondered about during EVSE charging. I'm interested to see what voltage it settles to about 1 hour after the EVSE charging finishes.
     
    #192 Mark57, May 6, 2020
    Last edited: May 6, 2020
  13. Hicksite

    Hicksite Member

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    Is the BM2 measuring surface charge at this point?
     
  14. Salamander_King

    Salamander_King Senior Member

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    Yeah, that's what I am interested too. With BM2, I can also monitor 12v charging happening during driving in real-time. With the onboard charging system when the car is in READY state and if the 12v SOC is below 12.6v, the system charges it well above 14v. It stops charging once the 12v SOC reaches ~12.6v and seems to keep trickle charging it until the car stops. This high voltage charge does not seem to happen during EVSE plug-in.

    The first screenshot is when the onboard charge system actively charging 12v battery when the car is in READY. The lower graph is the day when I drove my car ~1 hours, and 12v was being charged during the trip.

    Screenshot_20200502-124123.png

    screenshot-photos.google.com-2020.05.06-13_04_12.png
     
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  15. Salamander_King

    Salamander_King Senior Member

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    I don't know the physics of surface charge, but the measurement during EVSE plug-in is definitely not the resting state SoC of 12v. As soon as the charging is complete, the 12v SoC will settle down to resting state. That is what we are interested in.
     
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  16. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Interesting and what you'd want to see in READY mode. I wish it would take more advantage of the EVSE charging input and bring the 12V battery up to a higher voltage level to charge it more rather than something (12.62v) below a 13.5v float charge. Probably a good reason to not do that but not sure why.
     
  17. bisco

    bisco cookie crumbler

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    i wonder if it's the new battery design
     
  18. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    When he gets the results we'll see what it's really doing. Need to wait after the EVSE charging is finished and then let the 12V bat settle for a while to know for sure.
     
  19. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Thread sidebar. FYI, as I mentioned before, after days of testing with multi-meter, I think instead of having a parasitic12V drain in the 4Runner, I just proved my 12V charger has gone wonky. When two different meters show a battery @ 12.59V and you connect the charger and it says it's 40% charged, I'd say the charger has a problem. It's a Schukmacher SC-10030A that shows the % charged and the Voltage. The voltage it detects is right, but the % is apparently not reliable anymore. I really like it but I no longer trust it. CTEK perhaps . . . hmm.

    Edit. I ordered the CTEK MXS 5.0 (40-206)

    Back to the thread subject.
     
    #199 Mark57, May 6, 2020
    Last edited: May 6, 2020
  20. Salamander_King

    Salamander_King Senior Member

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    OK, here is a verdict. 3.5hr charging using L1 EVSE to a full charge (the traction battery had 40% SoC at the start) resulted in a net gain of 0.2v of SoC in 12v battery. During charging, the 12v battery is maintained at ~12.6v, but after the charge is finished, even though the charging cable remained plugged in, 12v battery stabilized down to roughly the same SoC as before the charging started. So, it is clear that EVSE does maintain the 12v SoC during charging but it really does not charge up the SoC much higher than initial SoC.

    screenshot-photos.google.com-2020.05.06-20_10_22.png
     
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