I went out to my car this morning -- 2020 Kona electric, not quite 4 yrs old, just 20,000 miles on it -- and saw that I apparently hadn't closed the driver's door properly. No biggie, I thought. I've done this before with no consequences. But this time the car is dead as a doornail. It literally won't do anything -- no lights come one, won't start, won't take a charge (the battery was at about 70%), nothing. I am waiting for the dealer to call me back now. Anyone got any inspirations? This is about the worst possible day for this to happen!!!!
An open door can easily drain the 12V battery before the next scheduled 12V charge event. Unfortunately the car is not able to actively detect and respond to this mistake.
You might want to have them measure the voltage as it is before jumping. If it's very low like under 5 volts you may find it less reliable ongoing after charging. You can charge it yourself by placing the car in Utility Mode for an hour once it's jumped.
It did turn out to just need a jump. Once the car was going I needed to do a fair amount of driving and all seems well. I had mistakenly believed that the car could sense when the 12v battery was getting low and charge it from the main battery, thus making it immune to having a dead 12v from something dumb like failing to close your door properly. Clearly I was mistaken.
I learned the hard way that our Honda Clarity PHEV charges its 12V battery from the traction battery only when the car is "running" (ie. turned on). Once, after not driving the Clarity for 3 weeks, the 12V battery became discharged (parasitic drains?). That's when I realized I couldn't put the electrified car in neutral and push it backwards without a working 12V battery. The front of the Clarity sits under shelves on the rear wall of our tiny garage. There is no way to raise the hood more than about 7 inches when it's parked there. Also, there is almost no space on the right side of the Clarity because the lawnmower and snowblower are parked there. Here I am crawling sideways next to the Clarity to connect my charger to the battery under the hood I could raise only 7 inches:
Looks painful, my guess is you have removed the shelf (once able to move the vehicle) or start backing in
That is the idea, but from what I understand one of the downfalls with this type of charging system (parameters - pay attention to the later ones - 2014 and newer) is it will only top off a healthy SOC 12V battery and will protect itself by not re-charging if the voltage gets too low. It may perceive a cell fault or an abnormal parasitic drain and shuts down the operation. Advice: keep a sharp eye on the battery voltage, try to keep above 12.4 V and use utility mode frequently to recharge. When opening the rear hatch, I generally start the car and put on the emergency brake so as to create less stress or if it will be opened for a prolonged period, put into utility mode. Apparently, this might be a good idea if any door is opened for a duration.
Mainly I think I need to just not be a dumbass who leaves the car door ajar when I go in the house. I've never had a problem with the 12v before this.
Aside from whatever current draw is associated with the door being open, the normally scheduled 4-hourly 12V charges will not commence. I can't imagine why it was designed this way, but that's the reality.
The shelf remains, and the Clarity's the trunk is higher than the hood, so I can't back it in. The problem arose because my MINI Cooper SE is so much more fun to drive than my Clarity PHEV, which is mainly used for infrequent long-distance trips. As a result, the Clarity was sadly neglected and it protested by discharging its 12V battery. My solution is to remember to drive the Clarity more often to ensure its 12V battery--trapped below that low-hanging shelf--stays charged. Actually, I could just turn on the Clarity for a half-hour to charge the 12V battery without ever driving it, but it is a great car and deserves more respect.
You are far from the only owner laboring under this "mistaken" belief! You're now part of a large and longstanding brotherhood of fellow dumbasses! Welcome.
Well, it happened again. This time, I don't see any sign of a door being left ajar or anything like that which would drain the battery. It's been about 36 hours since I last drove it, which isn't unusual, and it had been fine ever since my problem a couple weeks ago. So now, a really dumb question: How do I "keep a sharp eye on the battery voltage"? I have no idea how to do this. Any other advice? I don't want to have to keep getting jump-starts. Could my 12v be at the end of its life after only 20K miles?
You need a 12v battery logger. The BM2 logger has been frequently discussed in this forum, and many owners have one. It will give you current voltage plus 24/7 history charts on demand, via an app on your mobile; it is wired to the 12v terminals, and communication is via Bluetooth. See the thread from today “12v battery replacement”, and look for posts from @KiwiME for examples of BM2 charts. Given your 12v has failed a couple of times now, I can see a replacement being required very soon..
