Kona EV Electric Niro Ioniq - warning check your 12V auxiliary battery (car won't unlock, no start) 

Replacement batteries and sizes Please make first your *own* measurement to check - try battery group 140R H4 (AGM) or L1 26R (regular acid-lead) approximate maximum dimensions 8.2inch Long x 6.8inch Width x 7.8inch Height - note that the height is important because the cables to the battery will become too short for taller batteries. In mm that's 208mm Long x 173mm Width x 198mm Height In the US only H has replaced the 12V calcium "Rocket" battery for free on many cars still under warranty. In Canada and elsewhere most times owners paid from own pocket. Hyundai will replace it with a regular non calcium acid lead - no need to buy the one from them. A forum discussion www.insideevsforum.com/community/index.php?threads/12v-battery-replacement.13758/ Original Rocket battery appears to be 99R or T4 Battery dimensions chart (may contain errors) www.batteryequivalents.com/bci-battery-group-size-chart.html I suggest, when parking car inside garage, always double click the fob to lock it and shut off all computers. If left unlocked, computers may keep running background, forcing constant drain and recharge on the 12V which is powering everything except the motor. The original 'Rocket' battery is lead-calcium. Hyundai may be replacing it with a regular lead-acid one. I suggest removing the fuse for the AMS battery temperature sensor, if using a lead-acid battery, it may help keeping the charging voltage to a better voltage for the acid-lead battery More Hyundai Kia videos ru-vid.com/group/PLl-l6yge4ast930y0wMiD9IIlDUy1mPFS

Same issue for my Kona EV64 with only 20000Km. Thanks for information!

I've read that a lot of people have been left on the road with a dead 12V battery. My experience is that the car has 70,000 km, the car was manufactured in 2019 and the battery is still working. I have never had a single problem with the car.

If this is a 12V battery, and your multimeter show it is currently at 12.2 volts, why are you saying that it is only at 25% right now? It seems fully charged at that reading?

That’s just a regular lead acid not an AGM?