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Has no one tried leaving their headlights turned on????

This won’t bring back a dead battery but what it does do is keeps the DC to DC converter powered up all the time, so your 12v battery always stays over 13.5 volts while the car is running. If you turn your headlights off, or have them in automatic mode then the voltage can dip, A LOT. On my Niro, I never see voltage lower than 13.7 volts while driving with the headlights on. Turn the headlights off and I’ve seen voltage down to 12.3 volts. If you turn the car off with the voltage low then it will, over time, decrease the battery’s capacity.

So keep your headlights on!!!!
 

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Just chiming in to say my 2018 Niro PHEV has had this same problem too. The dealer was pretty useless and tried to tell me they fixed with a reset button that only exists on the HEV, not on my car so they obviously couldn’t show me. I am pretty sure they actually disconnected and reconnected the battery. It happened a couple times during COVID when I didn’t use the car for a week or two. I ended up getting one of those rechargeable jump start batteries and keep in the car in case I need it. I am charging it now before going out of town for a long weekend to be sure it is ready if I need it.
 

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2019 Kia PHEV and my 12V battery is also showing signs of going bad since I frequently see the discharge warning on the console panel. I expect that I will need to purchase a new 12V battery soon as I have noticed that the Kia dealership here in San Diego has been impossible to get a service appointment for other problems ("clunk" on acceleration) and they tend to not believe you when you state a problem which tells me that they will most likely say the 12V battery is fine and just waste my time and trip, etc.
 

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We've owned our 2018 Niro PHEV for almost 3.5 years. Do we get the auxillary charge message when not starting our car for several days? Yup, have been since day one of ownership. Has our 12 volt lead acid battery ever failed? Not yet.
That is excellent battery life! What I would expect from an alternator equipped car. Since we mostly hear about issues, this report is welcome. Wonder how many owner's batteries have lasted that long?
 

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I don't know why the PHEV can't have a piggyback lithium 12V battery like the HEV - with the battery relay reset on the dash.
I know this one! Lithium 12 volt batteries are hugely more expensive than lead acid ones. The reason they are specced in the HEV is only the weight savings to hit EPA numbers for marketing. Little point in saving weight in very heavy PHEVs where the point is "free" plug in miles as the selling point.
 

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I know this one! Lithium 12 volt batteries are hugely more expensive than lead acid ones. The reason they are specced in the HEV is only the weight savings to hit EPA numbers for marketing. Little point in saving weight in very heavy PHEVs where the point is "free" plug in miles as the selling point.
Could very well be the reason.
I would think the cost is far more important to Kia/Hyundai than the weight difference.
If the dead 12V battery issue becomes a great percentage of cars, Kia/Hyundai will have to do something about it...
 

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Once again, has no one else tried leaving their headlights turned on while driving the car?

I’m sitting in my car now with the car turned on, radio on, and headlights off and the battery voltage is 13.0-13.2 however, if I turn the headlights on the voltage goes up to 13.7-13.8 volts and stays there.
 

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I have 2020 Kia Niro Phev and 12v battery died twice in 6 weeks. Both times electric range was gone bit battery still showed 16%.Second time it failed check regenerative brake alert came up and car wouldn't restart after I stopped. Jump started both times. Brought back to dealership and they replaced battery straight away. They said there was a fault with the battery when they tested it and it seems to be a known issue. As there is a comprehensive warranty on the Kia I would suggest that you insist on a new battery being installed.
 

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As there is a comprehensive warranty on the Kia I would suggest that you insist on a new battery being installed.
In the US, 12 volt batteries are not covered by the auto manufacturer. The exception to that rule is the lithium 12 volt batteries in the HEV which are explicitly covered by the drivetrain warranty. Sometimes dealers sell an extended warranty here that could cover batteries, but I wouldn't think Kia dealers would push that since the manufacturer warranty is already so good.
 

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I learned something interesting today about at least some modern ICE cars. Their alternators may not be directly connected to the battery, but instead there is a relay between them that is opened by firmware. My sister needed a ride to pick up her 2015 Subaru that she bought used from her dealer of 30 years - loyal she is to brand and dealer! Had a failed battery, second one in the 2 years she owned it. Turns out that the software only charged the battery after the car had been driven 15 miles. So intermittent charging, just like the PHEV and BEV.

Besides replacing the battery under warranty (it was only one year old), the dealer also installed firmware updates to now instruct the car to charge the battery after 8 miles. He also said that the reason that Subaru switched to intermittent charging is that the alternator output was not sufficient to power all electronics (infotainment unit being the big one) and supply constant voltage to the battery. Sounds a bit bogus, but that is the official word. Seems to me the correct fix (not that we should care about ICE cars going forward) is a stronger alternator. Sad that even ICE cars have such a terrible system.

And the correct fix to all the PHEV/BEVs out there would be better engineering so that a constant charging voltage is supplied to the 12 volt battery from the traction battery. Got to wonder why they don't do that. Or they should pony up for a system similar to the excellent HEV's lithium 12 volt battery system. Of course, consumers would have to be willing to pay for the extra expense.

That 8 miles protocol before charging is also going to kill her battery. Running lights are automatic and since it is mileage driven charging instead of voltage, this is still a pure recipe for early failure. She is buying a desulphating smart trickle charger to use once a month to extend her battery life. Trickle chargers and jump starters is what we have been reduced to. On the plus side, the other parts of modern cars are far more reliable than decades ago.
 

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I learned something interesting today about at least some modern ICE cars. Their alternators may not be directly connected to the battery, but instead there is a relay between them that is opened by firmware. My sister needed a ride to pick up her 2015 Subaru that she bought used from her dealer of 30 years - loyal she is to brand and dealer! Had a failed battery, second one in the 2 years she owned it. Turns out that the software only charged the battery after the car had been driven 15 miles. So intermittent charging, just like the PHEV and BEV.

Besides replacing the battery under warranty (it was only one year old), the dealer also installed firmware updates to now instruct the car to charge the battery after 8 miles. He also said that the reason that Subaru switched to intermittent charging is that the alternator output was not sufficient to power all electronics (infotainment unit being the big one) and supply constant voltage to the battery. Sounds a bit bogus, but that is the official word. Seems to me the correct fix (not that we should care about ICE cars going forward) is a stronger alternator. Sad that even ICE cars have such a terrible system.

And the correct fix to all the PHEV/BEVs out there would be better engineering so that a constant charging voltage is supplied to the 12 volt battery from the traction battery. Got to wonder why they don't do that. Or they should pony up for a system similar to the excellent HEV's lithium 12 volt battery system. Of course, consumers would have to be willing to pay for the extra expense.

That 8 miles protocol before charging is also going to kill her battery. Running lights are automatic and since it is mileage driven charging instead of voltage, this is still a pure recipe for early failure. She is buying a desulphating smart trickle charger to use once a month to extend her battery life. Trickle chargers and jump starters is what we have been reduced to. On the plus side, the other parts of modern cars are far more reliable than decades ago.
I go along with the bogus claim that the alternator can't handle all electronics + battery charging - that is total BS.
As you say, a more robust alternator would solve that issue and there is no reason why the manufacturer can't do that..if that is really the issue. I remember many vehicles in the 80's with 80A alternators (police cars had 120A) and today's cars don't require that much.

I also agree with the lithium 12V system that the HEV has - much better system and I would certainly pay the extra if I had a PHEV or BEV.
 

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I also agree with the lithium 12V system that the HEV has - much better system and I would certainly pay the extra if I had a PHEV or BEV.
Could be $500 to $800 more. Kind of amazing that they engineered it into the HEV at a still competitive price. The HEV started production with a lead acid battery, the 2016 and 2017 models years worldwide (except North America).
 

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Could be $500 to $800 more. Kind of amazing that they engineered it into the HEV at a still competitive price. The HEV started production with a lead acid battery, the 2016 and 2017 models years worldwide (except North America).
I would pay the extra money but really wonder if it is that much more, or at least think the difference in price will narrow within the next few years.
For example, boost battery packs 15 years ago were lead acid and cost lets say $70. They were heavy but worked well as a safe boost battery.
Now I can purchase a cute, little, light lithium booster for approx 40% greater cost. I expect the cost of those lithium booster packs to decrease over the next 5 years.
Niro cannot continue long term with the current 12V setup for the PHEV & EV. I assume Hyundai is having the same problem.
 

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I’m wondering if Kia access may have something to do with battery drain. It seems the Kia is always looking for a cell and/or WiFi signal. If my phev isn’t driven for a while the battery dies. I took it in and the dealer said the battery is ok and you left the lights on. Don’t the lights go out after a couple minutes when the car is turned off?
note that the car is garage parked and plugged in and the lights were never on.
 

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I’m wondering if Kia access may have something to do with battery drain. It seems the Kia is always looking for a cell and/or WiFi signal. If my phev isn’t driven for a while the battery dies. I took it in and the dealer said the battery is ok and you left the lights on. Don’t the lights go out after a couple minutes when the car is turned off?
note that the car is garage parked and plugged in and the lights were never on.
Yes, the lights automatically go out unless you were to leave a reading lamp on or the hatch was not latched tightly - which I doubt is the case.
Kia has a problem and the only permanent solution will have to be addressed at the manufacturer level (future models)
 
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