Dead Battery (for starting the car)

What your dealer told you makes no sense to me. I left my Clarity parked in my garage for 2 weeks while on vacation and it was totally fine (batteries fully charged) when I came back. Note that I didn't leave the car plugged-in and even with that, the battery was full when I came back.

 

Did you leave the car itself on? Others have done this and after depleting the high voltage battery, the 12 volt battery will also be depleted. I've almost walked away from the car twice having gotten distracted after parking but not turning off the "ignition". Easier to do than you might think.

 

I don't drive my Clarity for days at a time and both the 12v and HV battery are not affected.
May be unrelated, but corporate Honda keeps telling dealers to keep the 12v battery charged on all their new unsold cars.
Honda won't warranty 12v batteries that fail if the dealer didn't keep them charged.
Customers are still covered, but the dealership would eat the cost instead of passing it on to Honda.
Might not be the issue presented by the OP, but yes, this is a thing and you can get a new car with a bad battery due to unthinking abuse from the dealer while the car spent months on the lot.

 

I left my car in the garage for 30 days with 67% of charge and when I came back it still had the same, so what the dealer told you makes no sense.

 

One more thing, the 12v battery may be slightly smaller, as the dealer says, but it doesn't have to do any of the heavy lifting that is required for ordinary gasoline cars.
There is no 12v starter.
The 12v battery is way over sized in a hybrid because the HV battery offloads engine starting from the 12v system.

 

What the dealer is telling her is "Honda is going to look real close at warrantying a new 12v battery and the dealership will probably have to eat the cost, so we hope she just walks away from the counter........is she still there?"

 

I have also left my car on but remember to shut it off when I get the warning after opening my door. I would think that it would automatically shut off after walking away with the key fob unless you leave it in the car when it is in your garage.

 

The 12v batt is smaller than normal. but it should last more than 5 days of not driving. I would give it a full charge and see if it happens again. If it doesn, then bring it to a different dealer and have them replace the batt.

 

I've sat waiting in hot parking lots with the A/C on for tens of minutes (car fully on, in "Park", and no ICE running) and I've never killed the 12 V battery. The caveat is that I really don't know whether the 12 volt battery is running the A/C or if the big battery is doing it. If is via the 12 volt battery, there is no doubt the Li battery is constantly charging it. Even when the car is in the "Off" mode, it's never really off. I've heard all kinds of sounds coming from the car sitting in my garage, especially when it's hot. I'm assuming that the mysterious mechanical and gurgling sounds reflect the cooling system automatically cooling the Li battery, which can be badly harmed if it gets too warm.

 

I also went on vacation for 2 weeks and the batteries were just as I left them. We all could be such better Clarity salespeople than Honda hires.

 

The traction battery runs the AC on my Sonata plug-in. It doesn't make any sense to run an AC compressor off of 12 volts. Look to see if an orange cable is running to the AC compressor. Orange cables are high voltage lines.

 

I think it's more common today to walk away without shutting the engine down, because you have the keys on you and not in the ignition. Probably more common for electric vehicles since you would not hear anything, specially if you leave the keys inside the car. Otherwise, you will hear the alert sounds for taking the key fob.

 

We were also on vacation for 10 days... just got back last night. This morning, we were able to turn on the car with no issue. Before we left, I made sure the battery was fully charged at 100%. This morning, it shows 99%... so I think the car is using draining some juice from the battery, but it should not drain the 12v battery.

Looks like this might be an isolate incident. Did you happen to leave some "auto" settings ON, like "auto" head light? We typically leave it in OFF position, and turned it on when necessary when driving at night.

 

White woman’s dealer blow smoke where great light in sky not shine. He heap bad dealer. No trust him.

The Clarity’s 12 v battery is rated at 310 CCA and the Fit’s battery at 340 CCA so it’s only 10% less. His argument is meaningless and he’s just trying to brush you off and not have to deal with it.
The dealer is cautioned by Honda to keep both the 12v and 17 kW traction battery charged to prevent permanent damage. Evidently many are not doing this. The dealer is mandated by Honda to check the Amp Hr of the 17 kW battery and to perfom a Check of the 12v battery.
Here is how they are supposed to check the 12 v battery (taken from Honda’s PDI doc):

5. Check the 12-Volt Battery To ensure long battery life and that the customer gets a fully charged battery, you must check it at these times:
 When the vehicle first arrives at the dealership
 During the PDI (if done at a later date)
 At regular intervals (if stored)
 Just before vehicle delivery
Test the battery with the ED-18 battery tester following S/B 88-023,
Battery Testing and Replacement.
If the ED-18 does not show GOOD BATTERY, charge the battery with the GR8 battery diagnostic station.
Write down the GOOD BATTERY 10-digit code in the PDI and Final Delivery Checklist booklet.
During the PDI, write down the code in the “Under Hood - Engine Cold” section.
Then, at vehicle delivery, test the battery again, charge if needed, and write down the new code in the “Final Inspection (At Delivery)” section. NOTE: Make sure the ED-18 has the latest software installed before using it.

Your battery should not have run down in less than a week with the car off. Either there is a problem with the car charging or the battery is weak and cant hold a charge.
If I were you, I would demand your dealer show you both the PDI and the print out from his checking the 12v battery (which they should have done at least once) if you did not get them at delivery. And have them test your battery now to see if it passes. Mine tested at 346 CCA and 12.46v at 73 F at Delivery.
If they can’t produce the PDI and a test print out, then I would demand they replace your battery because they did not follow Honda’s guidelines and damaged it.
And remember, you can have warranty work performed at any Honda dealer.
Let us know what you find out after testing the battery.

Here’s what the test looks like.

 

We never use the Park button when exiting our Clarity. We simply press the On/Off button, which both turns off the car and puts it in Park. Am I missing something? When exiting the car, why press 2 buttons instead of 1 and risk leaving the car powered up if you forget to press the On/Off button after pressing Park?

 

The sad attempt of an excuse provided by the dealer is simply unacceptable.
It infuriates me when people can so confidently make up total BS and lie so casually to people.

There is no way that an auto manufacturer would make a car that goes dead in so little time.
If it was 3-6 months, then maybe I can see something like that happening.

So what the dealer is also telling you is that the clarity is an inferior car with unrealistic owner requirements where you cannot even park the car at an airport for a week to travel.

 

@insightman I think it's mostly old habit. You put the car into park before turning off the engine. I also switch between the Clarity and a Maxima so it's natural to do same for both.

 

If you didn’t leave anything on and the 12v battery died in 5 days, you need a new 12v battery. It was likely damaged (sulphated) by the dealer leaving it discharged on the lot for a long time. However, I’m concerned that you write the battery went from completely charged to 0%. There is no indicator for the 12v battery, so how did you know it had a full charge? The 12v battery by itself does very little in the car. It just energizes the relay to bring the big battery on-line when you push start and it keeps a few small things on while the car is off. Power flows through it for some uses while the car is running, but the electricity for those uses originates elsewhere. IMHO, the 12v battery in our cars would be a good application for a deep cycle battery. Good luck with the dealer. Don’t put up with having to deal with a frequent dead 12v battery.