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I'm not crazy, the attack has begun.
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The issue is that the driving habits of 'some' don't quite match how the manufacturers expect.

As a result, the periods of sub-optimal charging are (in all probability) mis-timed with their power-off events.

In an 'good ol' fashioned ICE', it'd just throw 14.4V at the battery all the time, which is totally fine for longevity but loses a small fraction of a kW.

The first move was to so-called 'mild hybrids' in which cars do not charge all the time but are activated for charging while braking only. So instead of a constant low level drain from the crank, there would be periods of very heavy drain during deceleration events.

Again not a biggie, one would notice problems with this system if there was slowed cranking.

But carry ideas like that over to BEVs and you can suddenly see a landscape of 'overly-clever ideas' coming forth from programmers who have no idea how a lead acid battery actually works other than as a black-box described to them (most probably by a manager, not an engineer, who is trying to capture a very complex part inside a one sentence sound-bite).

For sure, if you drive like the manufacturer has 'designed you to', then all will be well.

In much the same way that if you drove the NEDC cycle, you'd get NEDC fuel economy. I always beat NEDC so I can't see why anyone else would have a problem achieving it, same as you having no problem charging your car but not all drivers are like you.
 

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There are many of us I am sure that have never had this problem. My car was purchased in Sept 18 and I have never (fingers crossed!) had a problem with my 12v battery.
I am the same with my October 2018 model. Over the past year my journeys have been short, with the car being parked up for weeks while schools were closed during the two full lockdowns. I was expecting a failure, but none came.

I wonder if there's something that we're doing or not doing that avoids a bug. I am a creature of habit, a bit like a pilot executing a checklist before and after each journey! I've never had a problem with the boot latching, and I check every time.

Key data points for me:
  1. I start the car before operating anything like headlights, windows, or folding mirrors (habit after years of old cars, always get the car started before 'wasting' power!)
  2. No welcome or auto mirrors; I control them manually using the switch
  3. No auto lights; I turn them on or off as needed (I might change this behaviour if they ever start to handle daytime fog)
  4. Lock and unlock using the button on the drivers door
  5. No dashcam or ODB dongles fitted when the car is off
  6. Run car down to 20% before charging at home, about once per month at the moment but 2-3 times per month before Covid-19 closed my office in March 2020
 

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I have had the 12v battery problem with my 2019 eNiro. It let me down about 5 times before I took it to the dealers. The 1st time they told me they had test it and could find no faults. When asked, they couldn't tell me why it kept happening. I told the dealer this was the most unreliable car I'd ever owned .
Two weeks later I'm back, this time they fitted a new battery. Ask your dealer to fix it or at least try a new battery.
 

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I am the same with my October 2018 model. Over the past year my journeys have been short, with the car being parked up for weeks while schools were closed during the two full lockdowns. I was expecting a failure, but none came.

I wonder if there's something that we're doing or not doing that avoids a bug. I am a creature of habit, a bit like a pilot executing a checklist before and after each journey! I've never had a problem with the boot latching, and I check every time.

Key data points for me:
  1. I start the car before operating anything like headlights, windows, or folding mirrors (habit after years of old cars, always get the car started before 'wasting' power!)
  2. No welcome or auto mirrors; I control them manually using the switch
  3. No auto lights; I turn them on or off as needed (I might change this behaviour if they ever start to handle daytime fog)
  4. Lock and unlock using the button on the drivers door
  5. No dashcam or ODB dongles fitted when the car is off
  6. Run car down to 20% before charging at home, about once per month at the moment but 2-3 times per month before Covid-19 closed my office in March 2020
My usage is similar. The majority of my journeys are less than 25 miles each way. For your data points, mine are similar but I do use auto lights and have 2 dash cams. I charge my car when i remember or when the price is right or the PV is generating!
 

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EU base model with heat pump Sept '18
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552 Posts
No problem with my 2018-Oct Kona either, but I don't have the telematics and pay attention to the hatch closing.

Is there a good reason why the car's normal 12V systems can't be run from a 400V DC to 12V DC converter which will always have sufficient power as long as the car has power available?
I was under the impression that the Model 3 is heading in that direction by placing the DC-DC inside the main battery pack where it can be active ahead of the main contactor but I'm unaware if they've progressed any further.
However ... one issue specific to Li-ion technology is that the open-circuit voltage (OCV) is the only means of correcting the SoC calculation over time, so a small DC-DC would need to power an energy efficient BMS to evaluate this without measurable voltage drawdown.
In the case of the Konas affected by recall 200 (most of us, no doubt) I expect that the OCV is critical for detecting the onset of a problem in a single cell. As is sits today with Campaign 196, that evaluation depends entirely on energy from the 12V battery. Fortunately, it does that in just a few seconds and only every 1/2 or 1 hour for 4-6 hours following driving or charging events.
As an aside, Chevrolet has just announced a "fix" for the Bolt issue which appears to function much the same as our 196 update. I knew GM would pinch-pennies but I didn't expect anything quite as brazen as to leave owners stuck with potentially faulty cells. Customers who complain seem to be offered a buyback or upgrade to a new Bolt.
 

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Kona PremSe64k 2020+bluelink +ohme
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Discussion Starter · #46 ·
Firstly thanks to some incrediblely helpful and insightful contributions.

Okay on Friday I got a call from the garage to say that they had done a second deep discharge. The battery looked okay then they put it back on the car, ready for collection and bam! Sickeningly this was too late in the day for Hyundai UK to authorise a courtesy car. Whatever we had our second Phizer jab on Saturday - so not being able to do what we originally had planned meant we just vegged out in front of the TV and binged on Game of Thrones. And I mean binged!

We're now at Tuesday morning. I called the garage. The engineer had looked at the battery, which he had put on charge over the 3-day weekend. It looked okay. He reported that the draw from the battery was .35 amps and the hyundai tolerance is 0.5 amps (sorry for my 1volt nonsense in the first post). So at 0.35 he put it back in the car ready for collection.

One last test! Bam! The battery voltage now showed just 6 volts.

So definitively the battery is - to put it politely - not working. The engineer has written it all up for Hyundai UK. So now the ball is in their court. We still don't have a courtesy car. Next step SHOULD BE a replacement 12v and so how quickly that can be supplied and fitted.

Btw we partly chose Hyundai because it was a 15m bus ride. But their inability to provide courtesy car is mindblowing.

Actually what makes it worse for us is that our car was not recovered by breakdown recovery. If we had had the AA or whoever get the car to Hyundai then breakdown recovery would have provided a courtesy car. Instead, because we could jump start the car we drove it to Hyundai garage.
 

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@andyswarbs , I have no idea how they test the battery and say it is good. The same happens to me every time!

When my battery was severely damaged (I couldn't start the car) I connected it to external charger. 5 minutes later it says fully charged. Shortly afterwards the battery is dead again.
Connected to smart charger and despite being full in 5 minutes kept trickle charging overnight. Drove to Hyundai 15-20 minutes parked there while handing over the keys (just 5 minutes) and they even couldn't open the door.
They called me 2 weeks later saying the battery was fine but they will change it as recommended by Hyundai UK (along with sensor).

I have no idea what they use for battery testing :eek:
 

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LEAF N-TEC 62KW
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To test a battery, check the open circuit voltage. 12v = 25%, 12.7v =100%, below 11.9 = flat.
Then apply a known load and see how quickly the voltage drops. If the voltage falls rapidly the capacity is much reduced.*
Similarly, if the voltage indicates the battery is, for example below 25%, then a 40ah battery will require over 30ah to fully charge it, so for example, 4hours on a 10amp charger. If charging seems suspiciously quick, again, the battery is no where near its original capacity.

* If the sleep drain is .35a then a fully charged 40ah battery voltage should not drop to 12v for about 80 hours.
 
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