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?
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.