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Car Dies and shows "12 Volt Battery Charging System Problem", "Low Battery Charge. Power Reduced" Messages.

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Hello, trying to get some feedback on some trouble with our 2018 Clarity Touring. My wife was driving it yesterday and the car started showing a red battery warning light and the messages shown above in the subject. It also warned to stop driving as soon as possible. My wife pulled into a nearby parking lot and the car soon died. She was able to restart it a few minutes later and drive home, but the car died again in our driveway. The HV battery was still over 1/2 full. Seeing as it was -1 F outside, I figured the battery was crapping out as it was over 3 years old. I charged it a bit, parked the car in the garage, and let it sit on a battery tender for the night. The next day, I figured I'd give it a try. The car started normally but didn't even make it out of the driveway before the warnings flashed again. I then decided to replace the battery with a new one, but, again, it started normally but I didn't make it past the driveway before the warnings started again. I have performed an OBD scan using and OBDLink MX+ and Torque Pro and OBDLink apps and neither app showed a trouble code. Does anyone have ideas as to what is going on here? Are there fuses to check? Where? Thanks in advance for any input.
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Hello, trying to get some feedback on some trouble with our 2018 Clarity Touring. My wife was driving it yesterday and the car started showing a red battery warning light and the messages shown above in the subject. It also warned to stop driving as soon as possible. My wife pulled into a nearby parking lot and the car soon died. She was able to restart it a few minutes later and drive home, but the car died again in our driveway. The HV battery was still over 1/2 full. Seeing as it was -1 F outside, I figured the battery was crapping out as it was over 3 years old. I charged it a bit, parked the car in the garage, and let it sit on a battery tender for the night. The next day, I figured I'd give it a try. The car started normally but didn't even make it out of the driveway before the warnings flashed again. I then decided to replace the battery with a new one, but, again, it started normally but I didn't make it past the driveway before the warnings started again. I have performed an OBD scan using and OBDLink MX+ and Torque Pro and OBDLink apps and neither app showed a trouble code. Does anyone have ideas as to what is going on here? Are there fuses to check? Where? Thanks in advance for any input.
When you say "the warnings flashed again" after replacing the battery, are you sure that it was the same warnings that occurred with the previous battery or possibly different warnings? The reason that I asking is because of a very possible scenario:

- Your 12V battery as you suspect was done. Normally however this would only affect starting the car, but in some cases a really far gone 12V battery will cause warning messages to appear while driving. Somewhat unheard of however is for a bad 12V battery to cause the car to die once it is running, but it might be possible.

- After replacing any 12V battery in the Clarity, or even disconnecting a healthy battery for a few seconds, it is perfectly normal for the instrument panel to display several ominous warning messages about failures of VSA, ABS, TPMS and I think one other. Yes that is perfectly normal to see those type of warning messages anytime the 12V battery is disconnected. These messages clear in less than a mile of driving.

If it's not those messages, or whatever messages you are getting don't go away within one mile, then there would likely be something else wrong with the car. But without further details about what error messages you have been seeing I am leaning towards it being the scenario that I described. I.e. just a 12V battery that went bad, as you surmised likely due to the sub-freezing temperatures, and then the normal "boo" that the Clarity does whenever the battery is replaced or the 12V is disconnected.
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It's the same charging system and low battery power warnings each time. I did get the TPMS warning after replacing the battery but wasn't concerned about that. Definitely an issue with the 12v charging system.
It's the same charging system and low battery power warnings each time. I did get the TPMS warning after replacing the battery but wasn't concerned about that. Definitely an issue with the 12v charging system.
Apparently I misread, "The car started normally but didn't even make it out of the driveway before the warnings flashed again" and, "it started normally but I didn't make it past the driveway before the warnings started again" as meaning that the car has not been driven more than a few feet since you replaced the battery. If however you have driven it for more than a mile after replacing the 12V battery and the warning messages still persist, then it's something other than the scenario that I suggested.and something else is wrong.
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These are the warning messages I get....
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I checked the main 12V 175A fuse in the engine compartment fuse box and it is fine. New battery starts out at 13.3 volts. After driving a couple miles it is down to 11.9 volts. Running car in maintenance mode does nothing to increase battery voltage at terminals, where typically I expect to see over 14 volts from a running vehicle. Car is 2 months and 1 week past warranty expiration $%@#&!.
1) Had you reported this to the dealer before your warranty expired?
2) It sounds like error lies in the 12V system. It is possible that the inverter's 12V circuit has gone south
3) Try this, (which is something I have done with my former Prius) when you are near a 12V charger:
A) turn off the engine
B) turn on the cabin lights
C) turn on other 12V items
D) after a few minutes, the cabin lights should start to dim. If possible check the voltage of the 12V battery
E) Start the car, keeping it in park
F) Once started, if the cabin light should get brighter and the voltmeter should increase. If not the problem lies in the 12V charging system.
Report the problem to the NTSB. Research if there was a TSB issued to resolve this problem.
BTW, this is why I have an extended warranty.
Good luck.
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1) Had you reported this to the dealer before your warranty expired?
2) It sounds like error lies in the 12V system. It is possible that the inverter's 12V circuit has gone south
3) Try this, (which is something I have done with my former Prius) when you are near a 12V charger:
A) turn off the engine
B) turn on the cabin lights
C) turn on other 12V items
D) after a few minutes, the cabin lights should start to dim. If possible check the voltage of the 12V battery
E) Start the car, keeping it in park
F) Once started, if the cabin light should get brighter and the voltmeter should increase. If not the problem lies in the 12V charging system.
Report the problem to the NTSB. Research if there was a TSB issued to resolve this problem.
BTW, this is why I have an extended warranty.
Good luck.
Hello,
The problem just started this friday. There was nothing to report previously.
I have already run the battery down and tested to see if the car is charging it. It's not.
I'll check the NTSB. Thanks!
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Try the NHTSA (safercar.gov) instead of the NTSB. However, since this doesn't appear to be a common issue, I'm not sure a single report would cause a recall.
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Dropped car off at local Honda dealer yesterday. Problem has been diagnosed as a bad HV battery assembly and requires replacement of the entire assembly, which costs over $6k I was told. Thankfully, it is covered under the 8 year battery warranty. Now we just have to wait for it to arrive...
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Dropped car off at local Honda dealer yesterday. Problem has been diagnosed as a bad HV battery assembly and requires replacement of the entire assembly, which costs over $6k I was told. Thankfully, it is covered under the 8 year battery warranty. Now we just have to wait for it to arrive...
Well, from the description of the error message it wouldn’t seem like the problem is with the HV battery. However, if Honda is willing to replace the HV battery at no charge to you, then more power to them! (no pun intended)

Make sure you let us know how it finally turns out.
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Apparently, the 12V charging system is a component of the HV battery system, and cannot be repaired or replaced as as subassembly. At least, not by the dealership.
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Dropped car off at local Honda dealer yesterday. Problem has been diagnosed as a bad HV battery assembly and requires replacement of the entire assembly, which costs over $6k I was told. Thankfully, it is covered under the 8 year battery warranty. Now we just have to wait for it to arrive...
Woohoo! You won the battery lottery!

Be sure to ask for documentation of any warranty on the new assembly, and insist that the batteries be new, and not refurbished.
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and insist that the batteries be new, and not refurbished.
I guess you could try, but the warranty explicitly states you are not entitled to a new battery.
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Apparently, the 12V charging system is a component of the HV battery system, and cannot be repaired or replaced as as subassembly. At least, not by the dealership.
The HV system charges the 12 volt system so sounds like no repair for that part of it. Interesting! Good on Honda for warranty. Didn’t know about that!
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So my new HV battery arrived at the dealer today and I hope to have my car back by the weekend...
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I had similar issues today while driving home from work. It has happened twice before, but this is the 1st time since I replaced my 12v battery. Previously I was able to just warm my car up in the garage overnight and it was OK. I am able to drive on electric only, but it says it will not run after that is used up. I have less than 26000 miles on my 2018 Clarity Touring. I will see if I can bring it in to Honda tomorrow.
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So my new HV battery arrived at the dealer today and I hope to have my car back by the weekend... View attachment 884
Can’t understand why HV showed 1/2 charge in this case? Hope the new EV pack solves the issue! Please let us know! Good luck!
I had similar issues today while driving home from work. It has happened twice before, but this is the 1st time since I replaced my 12v battery. Previously I was able to just warm my car up in the garage overnight and it was OK. I am able to drive on electric only, but it says it will not run after that is used up. I have less than 26000 miles on my 2018 Clarity Touring. I will see if I can bring it in to Honda tomorrow.
No question that you have an issue, but it does not seem to be a similar issue to what is being discussed on this thread because you are getting a completely different error message. Your error message seems to indicate a problem with the engine, or at least the system thinks there is a problem with the engine. This thread is a problem about a defective HV battery. Do you mind starting a new thread about the message that you are receiving because I think people will be interested to know more about it and how it is eventually solved.
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Definitely a different problem than mine and worthy of it's own thread. I hope you have success in solving it!

I had similar issues today while driving home from work. It has happened twice before, but this is the 1st time since I replaced my 12v battery. Previously I was able to just warm my car up in the garage overnight and it was OK. I am able to drive on electric only, but it says it will not run after that is used up. I have less than 26000 miles on my 2018 Clarity Touring. I will see if I can bring it in to Honda tomorrow
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