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I walked over to the car this morning after with the key in my hand, tapped the door handle and nothing... tapped again, nothing. Finally manually unlocked the car an there is no power at all. No dome light, can't even unlock the charge port door.
The car has been sitting unused in the garage for 2 weeks. I have no idea what is going on. Should I try to jump it or charge the 12 volt battery?
I manually opened the charge port and plugged it in but it won't charge without the 12 volt powering the computer to regulate I guess.
I guess I May have to call Honda service but they have been generally clueless about either of my Claritys.
 

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Most likely a jump start will get it started, either with booster cables or with one of those paperback-sized portable jump start batteries, which actually work really well especially on hybrids because cars like Clarity the 12V battery is used only to get the electrical system running and then the much larger HV battery takes over.

Once the car is on (make sure READY appears on the display) then the HV battery will immediately begin charging the 12V. Unlike a gasoline car where you would then need to drive the car for an hour or so to get the battery charged, with the Clarity you can just leave it sitting in the garage turned on (again make sure it says READY) and it will just sit there quietly charging the 12V battery. Of course check to make sure that your EV range is above 0. I'm not sure how long it takes to fully charge the 12V from fully depleted, but I would think leaving the car on in READY mode for at least thirty minutes will give it enough of a charge so that it will start the car without a jump, assuming that the next place you drive it to will be the dealer. If however you plan on first taking it to the grocery store or wherever then I would let it sit in READY mode for at least an hour to try and get the 12V more fully charged. And even then you will want to bring a portable jump start battery with you since the overall condition of the 12V battery is unknown at this time. But to be even safer the next trip should be straight to the dealer. Assuming that it jump starts there is no real need to have it towed to the dealer unless you just feel more comfortable doing that, especially if they do it for free under roadside assistance.

The dealer can check for codes to determine if there are any other underlying problems but assuming you are able to jump start it then the odds are that this was simply a case of a less than fully healthy 12V battery that drained after two weeks of sitting. The dealer will hopefully replace the battery for free under warranty as two weeks of sitting is a bit too short of a time period for a 12V battery to fully deplete especially for a car that is new. Unless there were any add-on accessories like a dash cam that were draining it. That being said a dead 12V battery after the car sits for two weeks is not unusual for Clarity, but not because the batteries are necessarily inferior but because many of our cars sat for a long time on dealer lots without being charged, which shortens the life of the battery.

Hopefully the dealer will replace the battery for free under warranty but that's up to them to decide. If they won't do it under warranty and you are hesitant to buy a new battery at this time, especially at dealer prices, then at least go to an auto parts store and have them test the 12V battery. If they say it needs replacement then at least their price will likely be a bit less than the dealer. If however you aren't that concerned about the cost then it will certainly be easier to just have the dealer replace it while you are there. Either way I wouldn't recommend going too much longer with this battery because once a 12V battery has been fully depleted even just once its days are numbered. Some might last another year or so after just one full depletion, but this battery already has exhibited that it's probably somewhat worn out, and again this may not be the first time it was fully depleted, no way to really know. We're coming into warmer weather now so it might make it through the summer but the risk goes up if you try and take this battery through next winter. Some people have reported that their Clarity can get fussy when the 12V battery is not working right so that's why it's probably better to just bite the bullet and plan to get a new battery now instead of trying to drag this one out any longer. Obviously if the dealer will replace it for free that becomes a moot point.

Looking ahead to when your car is back in the garage with a new battery, you will want to maintain the health of your new battery if the car will continue to sit for long periods. You can get a battery maintainer, which are a modern and much better version of the old trickle chargers. A popular brand is Battery Tender. Some people just leave the maintainer plugged in all the time as they have circuits to prevent overcharging, but it's safer to just use the maintainer every few days, i.e. connect the maintainer until it indicates that the 12V is fully charged then disconnect the maintainer. Alternatively you can simply turn on the car for about thirty minutes every few days or once a week or whatever (again make sure it says READY). Note that just having the EVSE charger plugged in won't by itself keep the 12V battery charged, as it only charges the 12V while it is charging the HV battery. And even then the charge rate for the 12V battery is much lower than when the car is in READY mode.
 

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I have the same problem. The car went dead the other day and I'm trying to charge the 12v battery with the NOCO Genius 1 portable charger but does seem to help. Car is still dead. Any other recommendations besides calling the roadside assistance? Thank you.
 

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I have the same problem. The car went dead the other day and I'm trying to charge the 12v battery with the NOCO Genius 1 portable charger but does seem to help. Car is still dead. Any other recommendations besides calling the roadside assistance? Thank you.
Typically if a battery is totally dead charging won't work, you have to jump start it. Jumper cables are one way but it's easier to use a portable jump start battery. They make small lithium jump start batteries that are small enough to fit in the glove box. They cost around $50. It's good to keep one in the car in case the battery dies when you are away from home.

After you jump start the car, leave it running for about thirty minutes to get the battery partially charged. The car can stay in EV mode since the 12V battery is charged by the HV battery whenever the car is in READY mode, whether the engine is running or not. After you get a partial charge on it, then you can use your battery charger to get the 12V battery charged back to full.
 

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Typically if a battery is totally dead charging won't work, you have to jump start it. Jumper cables are one way but it's easier to use a portable jump start battery. They make small lithium jump start batteries that are small enough to fit in the glove box. They cost around $50. It's good to keep one in the car in case the battery dies when you are away from home.

After you jump start the car, leave it running for about thirty minutes to get the battery partially charged. The car can stay in EV mode since the 12V battery is charged by the HV battery whenever the car is in READY mode, whether the engine is running or not. After you get a partial charge on it, then you can use your battery charger to get the 12V battery charged back to full.
Do note that a 12V PbA battery that has been allowed to fully discharge to "dead" will likely never perform to "new" levels again. I tend to replace them when this happens. Some "smart" chargers can partially recover them, but I have difficulty trusting the battery anyway. YMMV
 

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Do note that a 12V PbA battery that has been allowed to fully discharge to "dead" will likely never perform to "new" levels again. I tend to replace them when this happens. Some "smart" chargers can partially recover them, but I have difficulty trusting the battery anyway. YMMV
Agreed that once a battery gets drained you can no longer count on getting a full life from it. Although I have had batteries last several years after being discharged. But probably they would have lasted even longer had it not been discharged. Replacing proactively is best especially if the battery is already several years old, but nowadays with the portable jump starters that are available, and the fact that hybrids require so little power to start, I'm not as concerned about it and if the battery is not that old I keep running it.

Although I tend to be more cautious immediately after a discharge event, especially if I don't know what caused it, as it could be a sign that the battery is reaching the end of its life. But if it works fine after that, then I just keep it, although again knowing that it may not last quite as long.
 

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Agreed that once a battery gets drained you can no longer count on getting a full life from it. Although I have had batteries last several years after being discharged. But probably they would have lasted even longer had it not been discharged. Replacing proactively is best especially if the battery is already several years old, but nowadays with the portable jump starters that are available, and the fact that hybrids require so little power to start, I'm not as concerned about it and if the battery is not that old I keep running it.

Although I tend to be more cautious immediately after a discharge event, especially if I don't know what caused it, as it could be a sign that the battery is reaching the end of its life. But if it works fine after that, then I just keep it, although again knowing that it may not last quite as long.
I tend to remove them from service in a vehicle, and use them for less mission-critical applications. For example, I've got a garage vent fan that has some PV, a charge controller, PbA battery (ex-automotive) and temp controls attached. This way, it fires up the fan when the temp gets above a setpoint, but can run off the battery after the sun goes down to cool off the garage to the lower setpoint. Far more effective than simply connecting PV to a fan, and relatively cheap to set up.
 
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