Battery discharged for no apparent reason

[PaFromFL]

I parked and locked my Genesis last night at 9:30 PM and when I tried to unlock 13 hours later, nothing happened. I popped off the lock cover and manually opened the door and hood. The battery was down to 5.5 V. I checked the headlight switch and it was on automatic. After charging for an hour, the car restarted properly five times while running errands.

Batteries can intermittently die from the FL heat, but I have to wonder if something else malfunctioned and drained the battery. Any ideas?

 

[Mark_888]

I parked and locked my Genesis last night at 9:30 PM and when I tried to unlock 13 hours later, nothing happened. I popped off the lock cover and manually opened the door and hood. The battery was down to 5.5 V. I checked the headlight switch and it was on automatic. After charging for an hour, the car restarted properly five times while running errands.

Batteries can intermittently die from the FL heat, but I have to wonder if something else malfunctioned and drained the battery. Any ideas?

Please change your car from "Drives a Hyundai Genesis 3.8 V6 Sedan" to "Drives a Hyundai Genesis 2G 3.8 V6 Sedan" (or whatever for 2015-2016 2nd generation model).

 

[kn5owa]

I parked and locked my Genesis last night at 9:30 PM and when I tried to unlock 13 hours later, nothing happened. I popped off the lock cover and manually opened the door and hood. The battery was down to 5.5 V. I checked the headlight switch and it was on automatic. After charging for an hour, the car restarted properly five times while running errands.

Batteries can intermittently die from the FL heat, but I have to wonder if something else malfunctioned and drained the battery. Any ideas?

1. Maybe you just gotta old batt. & need a new one. You didn't give the age. Replace at 4 years.

2. Maybe you need another Fob battery - you didn't give the age

3. Turn off any and all "automatics"

4. Maybe you gotta bad alternator

5. Buy a battery load tester first, read the instructions. Cheap & well worth it. Harborfreight has a good one - two great big meters.

A. Test your present battery at something like 200 amps. with your new load tester - should hold at 10 volts or better for 15 seconds. If it doesn't - then shop new battery.

B. Use said load tester to test the alternator - put it across the batt. terminals. Start the engine - should read 14 Volts - give or take a half volt or so.

Good luck.

 

[PaFromFL]

1. Maybe you just gotta old batt. & need a new one. You didn't give the age. Replace at 4 years.

2. Maybe you need another Fob battery - you didn't give the age

3. Turn off any and all "automatics"

4. Maybe you gotta bad alternator

5. Buy a battery load tester first, read the instructions. Cheap & well worth it. Harborfreight has a good one - two great big meters.

...

Thanks for the suggestions.

1. I bought the car fresh off the boat in January 2015.
2. The fob worked immediately after connecting the battery charger.
3. It appeared that all settings and switches were in their usual state.
4. I assume a sensor would have noticed a bad alternator and triggered a warning message.
5. I might try that if the problem recurs. It started right up this morning.

 

[balfor]

I know this happened to many Lexus GS owners including myself. The consensus seemed to be a car computer or sensor would get stuck or locked up and continue to be powered when the car was off. The result would mysteriously drain the battery at random times. I had this happen only one time in two years of GS ownership, but it was irritating to say the least.

Hopefully this is not a bug in the Genesis but with the number of computers on board it is certainly possible.

 

[kn5owa]

I know this happened to many Lexus GS owners including myself. The consensus seemed to be a car computer or sensor would get stuck or locked up and continue to be powered when the car was off. The result would mysteriously drain the battery at random times. I had this happen only one time in two years of GS ownership, but it was irritating to say the least.

Hopefully this is not a bug in the Genesis but with the number of computers on board it is certainly possible.

I've seen a lot of posts on the forum about dead batteries that were miraculously brought back by charging or jump starting.

Maybe people are just leaving their trunk lids open or something

 

[Richard Ft. Lauderdale]

Mine recently (about a month ago) went dead. Tried to jump it with another car-no go. Tried to charge it-no go. I think the charger was bad. Have since gotten a new one.
Called Hyundai service and they didn't even try to jump it. Towed it to the dealer. They charged it and returned it for no charge even though the battery is only guaranteed for three years and the car was almost three and a half years old.
We had been out two nights before this and had valet parked the car and I did find the valet had left the headlights on but I did not discover this until the battery went dead. I was under the impression that the headlight system turned completely off when you turn the car off. I guess not. I always leave the lights on automatic. I will remember to check after valet parking from now on.

 

[jsmit86]

Genesis G2 Headlights do turn off automatically if left in the on position with the ignition off.

 

[Sal Collaziano]

I had the same exact thing happen to me when I first got my 2015. They replaced the battery at no charge...

 

[PaFromFL]

It's been starting up fine so far. Right now I think a computer or sensor glitch in the shutdown procedure left something on. If it happens again, I'll suspect a flaky battery.

______________________________

Help support this site so it can continue supporting you!

 

[kn5owa]

We had been out two nights before this and had valet parked the car and I did find the valet had left the headlights on but I did not discover this until the battery went dead. I was under the impression that the headlight system turned completely off when you turn the car off. I guess not.

Even my 10 yr old Sonata turns off the headlights automatically after you park the car with ignition off. I think the feature is undocumented, though.

Now I gotta try out the Genesis for that feature.

 

[Mark_888]

Even my 10 yr old Sonata turns off the headlights automatically after you park the car with ignition off. I think the feature is undocumented, though.

Now I gotta try out the Genesis for that feature.

If it is on auto, it will shut off when ignition is off. But I believe you can manually turn it on.

 

[Alwaysforward]

Mine shut off no matter what setting they are on.

 

[Navion 49]

It is a glitch in the start/stop switch. Mine did the exact same thing and battery was dead in the morning. Several new car manufacturers are having this same intermittent problem with the switch not shutting down everything when it is turned off and it drains the battery overnight. FYI.

 

[kn5owa]

It is a glitch in the start/stop switch. Mine did the exact same thing and battery was dead in the morning. Several new car manufacturers are having this same intermittent problem with the switch not shutting down everything when it is turned off and it drains the battery overnight. FYI.

If that's the cause, it would explain a lot -- there have been posts blaming everything from agm batteries to trunk lights.

 

[TbonePdx]

My battery went dead too, after being parked for 5-6 days in my garage. The battery was down to 3.6V. Got a jump start and have yet to have any more problems. Keeping my fingers crossed.

Tony

 

[circuitest1]

My 3.8 RWD Ultimate battery went dead twice in five months. The battery would not charge and could not be jumped when using the connection points in the engine compartment. In both instances i had to use the trunk terminals to Jump start the car and also to recharge the battery with my new AGM Charger. it took 22 hours to fully recharge the battery. My dealer tested the battery and said that it is fully functional, he also said that the engine connection points tested OK.

I second time the battery discharged, I had stopped the car with the transmission in the drive mode. I had to restart the car and put the transmission in neutral before turning off the ignition once more. This may or may not be significant as a cause of battery discharges.

 

[kn5owa]

Mine shut off no matter what setting they are on.

As you would expect - same as my Sonata

 

[Pitchinwedge]

Mine also simply died overnight. Had to call roadside assist twice. The second time, I went straight to the dealership. They said it was a bad battery and replaced it under warranty. Not sure if it truly was the battery or not some other electrical issue. Either way I'm happy I only have 2/3 left on my lease. So glad I didn't buy.

 

[circuitest1]

Battery discharged again for the third time in six months. Last two occurrences happened after a 200 miles drive. This time trunk would not open while standing by it with the key. Tried to reset the switch in glove box, as well as driver's screen menu to no avail. The next morning the battery was completely discharged. A short while back, we did not drive the car for over two weeks. Upon our return I checked the battery and the charger showed a 50% charge. Problem does not seem to be with battery, but with one of the on board circuit boards which under some conditions seems to keep the car fully operational, even though the engine is shut down and the key removed from the car.