A handful of forum members have reported unexplained problems with the 12V battery going flat. I noticed that Kia released TSB 163 in May that might be relevant. It applies to Niro PHEV, Optima PHEV, and Soul EV (Niro HEV is not in this list).
For Niro PHEV's it seems to be limited to the 2018 model year, with production dates between September 26, 2017 and March 30, 2018. I think that leaves me out, which is kind of a bummer, because I've been looking for an explanation as to why I'm now seeing the notification that battery saver plus ran almost every time I start my 2018 PHEV (meaning it runs almost every night).
For anyone who is interested, you can find the TSB on the NHTSA web site: hopefully this link will work for you: https://static.nhtsa.gov/odi/tsbs/2019/MC-10160618-0001.pdf
It talks about how a technician can investigate the possibility that the rear door latches might be putting a parasitic drain on the 12 V battery while the car is off.
For the DIYers in the crowd, unfortunately it refers to a shop manual that most of us don't have free access to. But it does make the point that if you know how to correctly connect an ammeter in the 12V circuit, then after the vehicle is in sleep mode (presumably the shop manual describes how to discover whether it's in that mode or not - I'm pretty sure that having your key-fob far away is part of the formula), then if the parasitic draw is less than 50 mA, you don't have a situation that the factory considers problematic. If you have more than 50 mA draw in sleep mode, they seem to be suggesting that the rear door latches should be replaced.
For me, the 50 mA number is new information that's good to know. Unfortunately, I still have a blind spot in that I don't have all of the other information mentioned in the shop manual about "Prepare the vehicle for a parasitic draw inspection".
Hope this info helps someone. Anyone who has a concern that this might apply to them can first check their date of manufacture, which appears on a label on the driver's door jam. If you fall into the date range specified above and if you have a concern about this, you could ask your dealer to evaluate your car for this TSB. The title of the TSB is "PARASITIC DRAW INSPECTION AND REAR DOOR LATCH REPLACEMENT"
For Niro PHEV's it seems to be limited to the 2018 model year, with production dates between September 26, 2017 and March 30, 2018. I think that leaves me out, which is kind of a bummer, because I've been looking for an explanation as to why I'm now seeing the notification that battery saver plus ran almost every time I start my 2018 PHEV (meaning it runs almost every night).
For anyone who is interested, you can find the TSB on the NHTSA web site: hopefully this link will work for you: https://static.nhtsa.gov/odi/tsbs/2019/MC-10160618-0001.pdf
It talks about how a technician can investigate the possibility that the rear door latches might be putting a parasitic drain on the 12 V battery while the car is off.
For the DIYers in the crowd, unfortunately it refers to a shop manual that most of us don't have free access to. But it does make the point that if you know how to correctly connect an ammeter in the 12V circuit, then after the vehicle is in sleep mode (presumably the shop manual describes how to discover whether it's in that mode or not - I'm pretty sure that having your key-fob far away is part of the formula), then if the parasitic draw is less than 50 mA, you don't have a situation that the factory considers problematic. If you have more than 50 mA draw in sleep mode, they seem to be suggesting that the rear door latches should be replaced.
For me, the 50 mA number is new information that's good to know. Unfortunately, I still have a blind spot in that I don't have all of the other information mentioned in the shop manual about "Prepare the vehicle for a parasitic draw inspection".
Hope this info helps someone. Anyone who has a concern that this might apply to them can first check their date of manufacture, which appears on a label on the driver's door jam. If you fall into the date range specified above and if you have a concern about this, you could ask your dealer to evaluate your car for this TSB. The title of the TSB is "PARASITIC DRAW INSPECTION AND REAR DOOR LATCH REPLACEMENT"