12v fully charged back but can't start car

Discussion in 'Clarity' started by Luke001, Nov 15, 2020.

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  1. Luke001

    Luke001 New Member

    Hello clarity gurus,

    So I guess my 12v battery died or sulfurated? Was able to use a battery maintainer/ charger to do a low voltage repair, eventually charging it back to full. It's now showing 12.6 v when not on.

    But then I tried to start the car, of course the system says everything is not working and asks me to press on the brake and start button, for some reason it won't let me start it at all, feels like the brake won't even allow me to press it down.

    I haven't tried rebooting the car yet (disconnect the negative for a bit and then reconnect).

    Just wondering if someone might have a tip,

    Thanks in advance for your help.
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  3. aapitten

    aapitten Active Member

    I would try the 'reboot' you mentioned. Do you have someone who can watch the volt meter while you press the 'start' button? Maybe you have a failed cell or something and your voltage is sagging too low if there is any load (like the computer or high voltage contactor) applied. Alternatively, you could try leaving your charger hooked up while you try to start. Given the low power draw of our cars, I wouldn't expect it to cause an issue (and most chargers have overcurrent built in anyway.)

    As far as your pedal not going down, if you pressed it a couple times already, you probably bled all the vac out out of the brake booster. It should go back to normal as soon as the car gets powered up. (At least I assume we still have a traditional brake booster - just driven from an electric pump. Perhaps I am wrong.)
  4. Luke001

    Luke001 New Member

    Thank you for the reply aapitten, I did try to disconnect the negative for about a minute from the 12v, then reconnect, but no luck. Its almost like it doesn't recognize that I'm pressing down the brakes to start the car. I didn't have anyone to watch the charger as I'm trying to start the car.
    I have a gooloo battery charger, maybe need to find someone to watch the charger while I try. Thank you again for your suggestions.
  5. JFon101231

    JFon101231 Active Member

    Strange. I know one time when I killed the 12-volt battery on mine I didn't need to do anything special once it was recharged.
    (Edit, realizing now that was my former Fit EV)
    Last edited: Nov 16, 2020
  6. My experience with a dead 12V battery was that the key was required to open the door and absolutely nothing came on inside the car after pressing the power button. No dash display, no interior lights, nothing.

    After connecting a lithium jump pack, the car came to life and the display informed me of all the terrible things that could occur should I fail to deal with them before proceeding. I drove it 20 miles and then used a conventional charger on it overnight. That was 10 weeks ago and it has been trouble free since.

    I’d say that you don’t have an issue with the 12V battery. Your display came on and when you connected the gooloo you essentially replaced the 12V battery.

    It may be time to utilize the Honda Roadside Assistance program.
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  8. Luke001

    Luke001 New Member

    Yeah I think that's what i'm going to have to do, I didn't know about the maintainer/charger before, so this happened before and was able to jump it and it and it started up with all the warnings (was able to press on brake and start button). Drove it around for awhile but didn't know that the 12v battery needed to be fully charged. Was able to drive here and there no problem, then after a week of no driving, i guess the 12v battery died. So i was able to open the door and get in to start the car that moment, and everything just shutdown, with the start button flashing. At this point, i finally got a battery charger and charged the battery (fortunately it was able to repair the battery). Unfortunately, now i'm at this point, can turn on accessory and power on, just can't start the car.

    I've never used the roadside assistant program, just wondering will they be able to take it to dealer i originally purchased it at? or will they only take it to the nearest dealer? Can i ride w/the tow truck person?

    Thanks again for all your help.
  9. I haven’t used roadside assistance.

    They may be able to diagnose and fix the problem on site.

    With the Covid situation, you probably won’t be able to ride in the tow truck.

    I’d guess that if towing/flatbed was necessary, they would tow to the nearest dealer.
    Luke001 likes this.
  10. MrFixit

    MrFixit Well-Known Member

    Well, unfortunately with a highly technical vehicle like this, it has been demonstrated that there is a drain on the battery when the vehicle is off / not used for an extended period.

    I do not have an explanation as to why you are having trouble recovering, but I think it is important to emphasize that we should all be aware that your battery WILL drain down over time.

    Bad things happen when 12V lead acid batteries go stone dead... I would not expect the vehicle to go 'bad' as you have unfortunately experienced, but it is very hard on a battery.

    I suggest that if all possible, do not let the car sit completely idle for an extended period without intentionally driving it for a bit, or connecting a battery tender / minder. My instinct is that an "extended period" would be several weeks, maybe a month. Shorter than that is probably OK.

    Please keep us posted as you resolve this problem !
    Last edited: Nov 16, 2020
    Luke001 likes this.
  11. Luke001

    Luke001 New Member

    You were right, they'd tow it to the nearest dealer.
    Unfortunately, I had two tow truck guys come out, one regular and one flatbed, but because of where my car is currently park, they can't tow it, so I need to find someone to help me move the car to the street. Thanks again for the message.
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  13. Luke001

    Luke001 New Member

    Thank you for the advice, I really wished I had known better. Someone will help me move the car tomorrow to the street so that Honda can tow the car. In the meantime, in did try to plug in the charger for the main battery, and it's not charging that either. At this point, I have a feeling that the OS is either corrupted or its stuck like in a windows xp safe mode...or worst a windows 10 unbootable state... just hope that Honda won't kill me and say that it's not under warranty....

    Thanks again all for your support
  14. insightman

    insightman Well-Known Member Subscriber

    I'd suggest leaving the 12-Volt battery disconnected for a half-hour. What can you lose?
    Luke001 likes this.
  15. Luke001

    Luke001 New Member

    That's a great idea, let me try that. Probably do it tomorrow morning thank you
    insightman likes this.
  16. In general, I agree with MrFixit.

    My personal experience differs somewhat. In ~15 months of Clarity ownership, the car has sat idle, unused and unplugged for a period of one month and another of 6 months. After the one month period the 12V battery read 12.45V and the car powered up without issue. After the 6 month rest, the 12V battery read less than 2 (two) volts. I measured it at least a half a dozen times.

    We have some high quality meters to measure voltage. I measured voltage on the other car, 12.7V. A AA battery, 1.8V. A lithium 2032, 3.2V. The meter reads accurately. With the lithium jump pack connected, it measured over 12V. Once the car powered up and the DC/DC converter was operating it measured over 14V.

    The car has started every time for the past 10 weeks and 2500 miles of daily driving. I can’t explain it. Recently I had to replace a 12V battery in a portable generator after attempting to bring it back to life for a week. It never got above 7V.

    I won’t be due for an oil change and tire rotation until March. I’ll have the 12V checked at that time.

    For Luke001, I don’t believe you have a 12V battery problem or that you will have any issues dealing with Honda on a warranty claim to resolve the matter.
    Luke001 likes this.
  17. Luke001

    Luke001 New Member

    Thank you for the information, I really hope it's something they can cover under warranty...times are tough..
  18. Luke001

    Luke001 New Member

    thanks again for the suggestion, i tried 30 minutes, and no luck. I'm wondering if something either got disconnected...

    Will wait for friend to come over to move the car, then off to the dealer.

    Thank all for your suggestions and help.
    insightman likes this.
  19. Luke001

    Luke001 New Member

    Was lucky enough that the car was able to set to neutral, and my friend and I moved the car to the street so tow truck guy could tow it. Took it to honda dealer and they just called me, told me that it's the main battery. and it's covered under warranty (phew!), else it would cost $8500 just for the battery. going to take 5-8 business days to ship, and about 2 days to replace it. Thank you all for your suggestions and help.
  20. MrFixit

    MrFixit Well-Known Member

    If this is really true, I believe it is the first example of a traction battery failure that has been reported in this forum.

    There was another owner who was asked by Honda to exchange his battery for a new one (it had not failed, but something prompted Honda to ask to get it back).

    If they are willing to communicate any details to you about the nature of the failure, please try to gather whatever information you can and report back. There are a lot of technical people here who would like to learn more about a traction battery failure.
    turtleturtle and insightman like this.
  21. Luke001

    Luke001 New Member

    Will do, so far the service advisor only said that they figured it our early today, but honda tech (i'm assuming honda tech support), wanted to check 3 things before considering the battery, i forgot what the 3 things were, maybe one is the alternator? but apparently all 3 things was okay, so they narrowed it to the battery. Will keep you posted with any additional information I can get. Thank you again.
  22. MrFixit

    MrFixit Well-Known Member

    This vehicle does not have an alternator.
    The 12V battery is charged from the traction battery.

    Are you certain that the problem is not with the 12V battery? There is a world of difference between a 12V battery failure and a failure of a traction battery. Did they specifically tell you that the repair would have been $8500? If so, that sounds like the traction battery. On the other hand, I would expect it to take longer than 5-8 business days to obtain.
  23. Luke001

    Luke001 New Member

    I'm pretty sure it's not the 12v battery, it was full when i checked it, and the two guys also checked it. The honda service guy said it would be around $8500. let me ask about the 3 things they had to confirm working before replacing the battery. I was too excited to hear that it was under warranty and must've blocked out listening to the rest. will check with them.

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