I would just turn it on for a few hours if letting it sit or in utility mode once a month or so ( you should see 14.7 V or so during the duration). Even though the charging algorithm has been improved it is still not quite what it should be, Also avoid Bluelink com and check the back hatch is "slammed shut". It is possible there is another type of phantom drain, but self monitoring seems to be the best scenario.
For me, the short term solution was to buy the smallest, cheapest battery jumper pack available. Finding and paying an independent service tech will be more expensive, take more time than 20 jump starts with the pack, and not necessarily fix the problem, which may well involve replacing a significant Hyundai subsystem. I got this pack at $85 for its compact size. They have larger cheaper ones with other features added and there's always a flyer online with discount coupons.
As a contrast other owner's posts have showed that the 12V battery can also charge on every 4-hour wake-up event, presumably based on the BMS's understanding of the 12V battery's state of charge (not likely the voltage). And from our understanding, the other likely purpose of the wakeup is to check the traction battery's isolation resistance and cell voltage difference. It's not clear what happens if those are found to be outside the acceptable range, perhaps a service light illuminates.
I have noticed the taper on other days.
Thanks for all the suggestions! Yes, I’m in Maryland. I already bought a portable jumper reading some other comments here. I’ll definitely look into the consumer protection complain if this happens again.
The 12 volt system heartbeat seems to have paused.
It seems after 2.5 days the system will resort back to it's previous cycle of checking every 24 H:
Thanks for this background.
Although it may seem intuitive, there's no indication that voltage is the parameter by which the Kona's system decides to charge the aux battery. Certainly if load and time conditions are controlled, voltage of a lead-acid battery does give a very good indication of SoC and that's perhaps why the BM2 attempts to do this on the display, keeping in mind that it is a generally-applicable tool. But here the Kona's system has little option but to significantly load the battery to reach the point where it can start to assess the situation. I don't think anyone has yet established the facts regarding what algorithm is used, but we do know there is an IBS (intelligent battery sensor) installed and one owner has even graphed (but not interpreted) the outputted data stream.
Thanks for the reports! The vehicle (and it's associated software) prefers to be driven and or charged as demonstrated by the screenshots. Where I have issues is a lot of short trips, mostly 10 to 15 kms which doesn't do enough to charge the 12 V battery. It's nice to see that these events do initiate some attempt at doing just that and the frequency of the top ups is much better than original, but I will keep doing what I have done for years on 3 EVs with the leaving on method every month for a couple of hours. I have checked the voltage (hood left open when doing this) and it stays @14.7 V for the duration. The only thing I find is the fuse box in the car (close to the battery) gets a little warm in hot conditions (probably some relay) but it seems to have worked fine.
Cheers.Thanks for the reports! The vehicle (and it's associated software) prefers to be driven and or charged as demonstrated by the screenshots. Where I have issues is a lot of short trips, mostly 10 to 15 kms which doesn't do enough to charge the 12 V battery. It's nice to see that these events do initiate some attempt at doing just that and the frequency of the top ups is much better than original, but I will keep doing what I have done for years on 3 EVs with the leaving on method every month for a couple of hours. I have checked the voltage (hood left open when doing this) and it stays @14.7 V for the duration. The only thing I find is the fuse box in the car (close to the battery) gets a little warm in hot conditions (probably some relay) but it seems to have worked fine.
Sure looks good when everything works the way it's supposed to.
I measured 12.83 V today (resting voltage) today, this is with the hood opened (open sensor disconnected by unplugging at the connector to the left of the rad area so no open signal on dash) locked and sleeping for 3 hours.
