[mungo544]

Yeah they had it over night the first time and the second time for five days. Of course it doesn't happen when it's there haha. But they said it doesn't die and there is nothing on the diagnostic

Please don't take offense to this question, but are you certain you are shutting down your car properly? If so, there are several things you can try to see if there is some type of parasitic draw making your battery die. Do this before shutting down for the night: 1. Turn your headlights to the off position. 2. Turn off all courtesy lights. 3. Put your key fobs as far away from your car as possible, maybe in a metal box. 4. Turn your infotainment system and hvac system off before you shut your car down. 5. Before you shut your car down for the night, drive for a few minutes in sport mode, preferably on the highway until the battery gauge reads at least 3/4 charge, preferably to as high as you can get it. Lock your car before you leave it for the night. Take note of the state of charge at shut down and again in the morning. Importantly, take photos of the state of charge so you can document the battery draw overnight. If there is a draw, eliminate one of the first 4 suggestions at a time over a 4 day period to see if it affects the state of charge. I know it is a lot, but Hyundai isn't helping you at all. At least if you can document the rate of discharge overnight, you can prove your point. My guess is if you fully charge the traction battery before shutting down for the night, your state of charge will go down, but maybe not enough to prevent you from starting. If it won't start even after fully charging, you likely have a defective battery.

 

[mungo544]

Any of those automatic features could be malfunctioning , causing a battery draw, including the key fob, which sends signals to the car. Manually disabling them can't hurt in a process of elimination. Running the car in sport mode will provide a fully charged traction battery to start with. That way, checking the state of charge before and after will be more accurate. If you start with a low traction battery, you are less likely to see how much power is drawn overnight before the traction battery disconnects from the 12 volt system. I agree that something is wrong with the car. These suggestions are a way to collect data to show Hyundai that something is wrong. They had it for 5 days and couldn't find anything. Collecting data proving an overnight battery drain will prove to Hyundai something is wrong. One extra data point I would suggest would be to take video on startup to prove that the car isn't starting. They say the defintion of insanity is doing the same thing over and over and expecting a different result. At least i am suggesting something different, and explain here my reasoning.