Battery losing charge when not in use

yanko said:

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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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.

PACVT said:

I have had issues with my 12v battery dying… always when I wanted to get someplace.. at least 4x in the last 30 months. Typically after sitting for a while.
I purchased a battery maintainer and a Bluetooth battery tester designed to Continually monitor the 12v battery. Diving does recharge the battery, and does drain while parked. My occasional short trips around town help but do not fully charge the battery.

Anyone else take a similar approach? observations?

any thoughts why monitoring and recharging the12v battery are not built-in — powered off the charger when plugged in?

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Like any car the Clarity 12V battery will slowly drain if the car is not driven. This is true even if the car is plugged in. That's because power only flows through the charge cable while the car is charging. So if you don't drive very much then the 12V battery doesn't get charged very much. I am guessing that you haven't experienced a dead battery since you started using a battery maintainer?

Now whether the battery should have died during the amount of time that your car was sitting is hard to say. Some people have left their Clarity sitting for a few weeks and it still started. Others it won't start after just a week of sitting. There are different variables, including the overall health of the 12V battery.

For those who don't have a battery maintainer, another option to charge the 12V battery is to simply turn the car on to READY mode and leave it on for about an hour. Whenever the car is in READY mode the traction battery will charge the 12V battery, regardless of whether the car is moving or not. Just remember to turn off the car when you are done! If you forget and leave the car turned on for a few hours it will gradually drain down the traction battery. No huge deal as the gas engine will eventually come on to charge the traction battery, but if it's in an enclosed garage that could be a problem. So set a kitchen timer or something to remind you to turn off the car.

It's a good idea to carry a portable battery jump starter in the trunk in case the 12V dies while you are parked somewhere. The small lithium jump start batteries work well and will fit in the glovebox, although I keep mine in the trunk.

A weak 12V battery will drain faster also. If your 12V battery has died four times, it likely now has a shortened life. When it comes time to replace it you can shop around but also check the dealer price. The Honda dealer price will be higher than say Costco, however Honda has a really good warranty on batteries purchased at the dealer, many people feel that the Honda warranty is worth the somewhat higher purchase price. The last time I checked the Honda warranty is 100 months, the first 36 months is full replacement at no cost, the remaining 64 months is prorated.

Also if your car is still within the original 3 year/36K warranty period you might be able to get the 12V replaced under warranty. Oftentimes people take it to the dealer and the dealer tests the battery and says it's good and they won't replace it under warranty. But then if the battery dies again say in a couple of months, they take it back to the dealer and oftentimes the dealer will then go ahead and replace it. If you had taken your car to the dealer after some of the prior incidents, they may have eventually replaced it under warranty. Or maybe not, hard to say, but if you have the car in for service you should also tell them about your dead battery experiences and there is a chance they will replace it.