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Discussion Starter #1
... to all the folk who've had 12V issues, strange and inconsistent behaviour, and so on... has anyone tried putting the 12V battery on a smart charger overnight? I'm fairly sure that some of these errors are due to the car not properly keeping the 12V battery charged up.

Our Kona had the same problem and it took Hyundai 18 months to finally roll out a fix (which involves every 4 hours the drive battery charging up the 12V battery if it needs it) and finally the slow but painful death of the 12V battery went away. Other EVs suffer the same problem - the i3, Zoe, even the new ID.3 do.

One "fix" is to either charge the 12V battery in the same way you would with an old-fashioned dinosaur-burner, i.e. with a trickle or smart charger. Another option is to leave the car on in some kind of "powered up" mode but with the doors locked (and the fob safely out of distance!). This should steadily charge up the 12V battery (I'm talking several hours here). Make sure of course that the car isn't unlockable and that lights, radio and all other drains are off. It might be that pressing the Play button for several seconds to supposedly power the car down, for example, actually leaves it charging the 12V.

I think you should be able to tell if it's charging the 12V by measuring the voltage on the accessory socket in the boot (ideally with one of those read-outs you just plug in).

Just a thought!
 

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Given that public knowledge of the drive battery-->12V charging fix, why do some vendors (VW, Polestar, etc) have persistent problems and still not just do that?

Seems simple enough to me, so I'm probably unaware of some important limitation to implementing that.... Are we not able to estimate 12V SOC well? Not able to reliably wake up the system to check q 4 hrs or whatever?
 

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I've heard a few different takes on this... In some vehicles it's not always the actual 12v battery, just any device that happens to be on the 12v and having problems can cause problems for the rest of the system.
 

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Discussion Starter #4 (Edited)
There are two aspects - one is that one of the devices in the car doesn't shut down properly and runs the 12V battery flat within hours (had that on my Kona at least 5 times now). The second one is where repeated short journeys result in the 12V battery not being charged up enough during those journeys to cope with all the load put on it during that journey plus the bits in between - i.e. a slow and gradual discharge. Had that one too as did most other Kona, Ioniq and e-Niro owners. The fix has been to more frequently wake the car up and top up the 12V battery. It used to happen once per day, now it's every 4 hours or so.

Different things, same end result (low or flat 12V battery).

A separate problem is an ECU going do-lally and writing all over the CAN bus that they all communicate on, but that's extremely rare these days. Failures in ECUs generally result (if anything) in simply grounding the CAN communications bus so nothing can communicate, at which point you get dozens of errors simultaneously on the dashboard saying everything and his dog has failed.
 

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Discussion Starter #6
True, of course :) but it involves bringing multiple ECUs out of standby mode at regular intervals, powering them up etc etc. No excuse though as all that stuff must exist anyway. Given that EVs have had 12V battery problems for nearly 10 years in almost every EV model, they really should be getting this right by now. Don't they even do basic homework?
 

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It is so utterly trivial to mitigate against this that it's absolutely baffling there is a problem. It's one line of code...

IF 12voltBatterySoC < 90% AND bigBatterySoC > 10% THEN turnOnBleedinInverterYouMuppet
I try to inject a bit of humor in naming and logic constructions when I code (which isn't that often). This is brilliant, though. I'm going to start including "muppet" here and there, I think.
 

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It is so utterly trivial to mitigate against this that it's absolutely baffling there is a problem. It's one line of code...

IF 12voltBatterySoC < 90% AND bigBatterySoC > 10% THEN turnOnBleedinInverterYouMuppet
<nitpick>
An inverter is used to convert DC to AC.... but you want DC to DC for charging the 12v battery from the drive battery
</nitpick>
 
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A week or so ago Ford was showing a pre-production Mach-E at some Motreal dealer. A number of pictures were taken and shared on Facebook and I found that one particularly interesting. The reps showing up the car from one dealer to the next has added a 12V charger in the frunk. So yes, all EV have the issue to some degree.
1507
 

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Discussion Starter #10
Yup, there you go. A lot of Kona owners now have something like that in their glovebox!
 

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It is so utterly trivial to mitigate against this that it's absolutely baffling there is a problem. It's one line of code...

IF 12voltBatterySoC < 90% AND bigBatterySoC > 10% THEN turnOnBleedinInverterYouMuppet
I assume the 12V battery is lead-acid. Are they not notorious in being difficult to gauge the power left without testing the specific gravity of the electrolyte? Never really got to grips with the leisure battery in my camper van. Found it difficult to definitive and consistent set of voltages. Different websites had different voltages/levels. Additionally, they should not be run down below 50% because they become damaged.
 

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Surely it can't be that difficult to just set up a separate connection to the big batteries to step down to 12V for the onboard systems and do away with the big lead lump altogether? I appreciate this may add in an extra drain, but surely these batteries are more flexible with regards to state of charge and it would take weeks for a 12V supply to discharge them to that point...

Or am I missing a vital point?
 

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Discussion Starter #14
Nope, because you need the high voltage pack to be physically isolated when not in use for safety reasons. You need the 12V to turn on the contactors for the high voltage pack, to then charge the 12V battery...
 

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Surely it can't be that difficult to just set up a separate connection to the big batteries to step down to 12V for the onboard systems and do away with the big lead lump altogether? I appreciate this may add in an extra drain, but surely these batteries are more flexible with regards to state of charge and it would take weeks for a 12V supply to discharge them to that point...

Or am I missing a vital point?
The high voltage is disconnected when the car is not in use, for safety amongst other reasons which could be engineered away i guess. The 12v battery is needed to power the systems at all times and to connect the high voltage battery when the car is turned on.

edit: @rgledhill beat me to it
 

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I assume the 12V battery is lead-acid. Are they not notorious in being difficult to gauge the power left without testing the specific gravity of the electrolyte? Never really got to grips with the leisure battery in my camper van. Found it difficult to definitive and consistent set of voltages. Different websites had different voltages/levels. Additionally, they should not be run down below 50% because they become damaged.
I think this has to be it. And the gravity of the electrolyte used in a hydrometer is a function of temperature too which just makes another parameter to measure/control/account for, especially in more frigid parts of the world.

I'm guessing Polestar must have included something like stevelup's code, but its algorithm for estimating the 12V SOC is off
 

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Discussion Starter #18
The Kona does have a system for measuring the State of Charge of the 12V battery, I think by putting it under a controlled load which allows it to measure the internal resistance and voltage. No idea if the Polestar also has such a system...
 

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Discussion Starter #20
True, but Hyundai got it wrong, and they've been making hybrids and EVs for years. They literally didn't fix it until around May, when our car got updated.
 
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