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Hi, I have a brand new Honda Clarity 2019. I had to travel for 12 days two days after I bought it. I charged it to 100% before I left. When I came back and got in, the battery was at less than 50%. This surprised me; this is not how my phone and iPad behave. It takes months for them to lose battery charge. I can't imagine why it would be using power just sitting there. Any thoughts?
Yanko
 

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Hi, I have a brand new Honda Clarity 2019. I had to travel for 12 days two days after I bought it. I charged it to 100% before I left. When I came back and got in, the battery was at less than 50%. This surprised me; this is not how my phone and iPad behave. It takes months for them to lose battery charge. I can't imagine why it would be using power just sitting there. Any thoughts?
Yanko
Where did you get the 100% and 50% numbers from the HondaLink app or from the infotainment screen? If from the infotainment screen that is not the amount of battery charge that is just an estimate of EV range, that estimate can vary quite a bit over time based on temperature and other factors, even if you haven't driven the car. The EV range is also well known to be inaccurate when the car is brand new, it gets more accurate after several days of driving.
 

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You shouldn't loose 50% of your battery charge in a week and a half. 50% loss over a few months, possibly, but not a week and a half. I'm assuming you're looking at the SOC (State of Charge) estimate on the driver's information area behind the steering wheel.

The Clarity will use some battery to maintain battery temperatures - was it really cold (below freezing) while the car was sitting? This will cause the car to run the resistive heaters to keep the battery warm while it's really full. Once the battery runs down some it's won't get damaged by the cold temperatures (full LiON batteries are easily damaged by freezing).

Something else to check is for a parasitic draw? This would cause the 12v battery to be discharged. The Clarity maintains the 12v battery charge using the main traction battery as a charging source. If the 12v dies you can't start the car's computers, which means the car won't start.
 
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The Clarity will use some battery to maintain battery temperatures - was it really cold (below freezing) while the car was sitting? This will cause the car to run the resistive heaters to keep the battery warm while it's really full. Once the battery runs down some it's won't get damaged by the cold temperatures (full LiON batteries are easily damaged by freezing).
That's news to me, did you read that in a Honda technical bulletin because it says nothing about that in the Clarity Owners Manual that I could find. The only thing close is that Canadian models have a battery warmer but the manual indicates that the battery warmer works only when plugged in.

Also my understanding is that damage occurs only when attempting to charge while the battery is frozen. That's why the manuals states that if the battery gets to cold you won't be able to drive or charge until the battery warms up.
 

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Discussion Starter #6
Sorry for the slow reply; I assumed I'd get an email when someone posts something to a thread I've started. I'll look into that.

Yes it might have been below freezing a few times while I was away. I was also unaware of battery heaters; the manual doesn't say that.
For my estimate I was using the number of bars in the left side of the dash screen. I didn't think this was drive range, since it gets all the way up after every charge but the drive range seems to change with the weather. Haven't had the car too long but I rarely get more than 38 miles estimated and real per charge.
So what I'm getting from these posts is that this is not normal, especially for a brand new car, so I should have it checked out. You guys agree?
Thanks!
Yanko
 

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Sorry for the slow reply; I assumed I'd get an email when someone posts something to a thread I've started. I'll look into that.

Yes it might have been below freezing a few times while I was away. I was also unaware of battery heaters; the manual doesn't say that.
For my estimate I was using the number of bars in the left side of the dash screen. I didn't think this was drive range, since it gets all the way up after every charge but the drive range seems to change with the weather. Haven't had the car too long but I rarely get more than 38 miles estimated and real per charge.
So what I'm getting from these posts is that this is not normal, especially for a brand new car, so I should have it checked out. You guys agree?
Thanks!
Yanko
Normally what I have heard about is the 12V battery being dead when the car had not been driven a week or two. Others have left their car sitting a similar time or even longer with no problem so the assumption is that people who's 12V died while they were gone, the 12V battery may have been weak already.

But I can't remember hearing about the traction battery losing charge like you described in just twelve days. Some have theorized that the traction battery charges the 12V. Well actually that is true but people who have tested with voltmeters have pretty much confirmed that the 12V battery is only charged when the car is on, or if the car is currently being charged. But when not plugged in, or plugged in but not charging, the traction battery will not charge the 12V.

So one theory is that maybe you accidentally left the car turned on? I have done that myself a few times when getting out of the car but I always get alerted by beeps when I try and lock the doors. But if the car was accidentally left on for a long time this for sure would drain the traction battery. If you didn't have climate control running then I think losing half of the charge in twelve days seems possible. If AC or heat was on however it wouldn't have made it more than a few hours. And I am guessing when you got back into the car after your trip you would have noticed if it was already on, so maybe the theory is unlikely, but it's all that I can think of at the moment.

As you mentioned I don't know of anywhere that the manual mentions a battery heater that operates when it is freezing, other than in Canada their models have a batter warmer but it apparently only works when plugged in.
 

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When the car is new - during my first week, the EV traction batteries were all off for me.
The onboard computers are probably trying to guess your range and will take a bit of time, driving and charging to be more accurate.

One day, it said I had 999 miles of EV charge, then dropped to 499 the next day after driving.
Finally, about a week later, it settled down to the normal 47 +/- miles of range per charge...
 

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When the car is new - during my first week, the EV traction batteries were all off for me.
The onboard computers are probably trying to guess your range and will take a bit of time, driving and charging to be more accurate.

One day, it said I had 999 miles of EV charge, then dropped to 499 the next day after driving.
Finally, about a week later, it settled down to the normal 47 +/- miles of range per charge...
The OP was looking at the bars on the left side of the display. That shows actually battery charge and is not affected by range estimates.
 

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Discussion Starter #10
OK, so I finally had a chance to repeat the experiment and now I got no loss of charge at all in 5.5 days.

I've had the car for 2 months now so it must have recalibrated itself. It's also true that we had no below-freezing temps, in case that was a factor.
So I'm satisfied for now.
 

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I had an issue with the 12 volt battery going dead if the car sat there for 10 -12 days. True, it was driven very little during that time. It was upsetting to me because it means I can't go away for 2 weeks, especially in the winter, without coming back and not being able to start the car. I had a number of back and forths with Honda. They did what they had to do in terms of having the car and battery tested by the dealer, but it still happened twice more. They would not offer any remedy except suggestions that I had to pay for. I felt that was inappropriate. The car was brand new and they were trying to tell me it happens to all cars. I have had many cars in my life and it has NOT happened. Not with Toyotas or other Hondas. I ended up buying a GB 40 battery booster which I keep in the trunk along with some booster cables. I have not had to use the GB 40 as yet, so can't comment on it.
 

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I also have fell victim to returning to my car after being on a two week vacation only to find the car would not start due to a dead 12V battery. First time it happened I thought it was operator error. Maybe I left the car in ACC mode by accident. It happened again a few weeks later with the car sitting in my garage for about a week. Took the vehicle into the dealer and had them test the battery. Battery according to them tested fine and they told me I should expect this due to the number of computers. I called BS to that statement.
 

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When the car is new - during my first week, the EV traction batteries were all off for me.
The onboard computers are probably trying to guess your range and will take a bit of time, driving and charging to be more accurate.

One day, it said I had 999 miles of EV charge, then dropped to 499 the next day after driving.
Finally, about a week later, it settled down to the normal 47 +/- miles of range per charge...
Isn't there a software fix from Honda for this? Early Clarities had a horrible time guessing remaining range.
 
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Yes, there was a TSB on updating range estimation software.

I had that done on it's first oil change at the dealer and has not been an issue....
 

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As a data point, I had my 2018 PHEV Clarity in storage for 6 months over Wisconsin winter, and when pulling it out in spring there was no noticeable loss of SOC of the drive battery compared to when I put it to bed in the fall (about 2/3 full). Had a maintainer on the 12V battery the entire time.
 
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