No, it's very similar lar.

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It proves that the 12V battery in EV cars can fail for various abnormal reasons, resulting in car breakdowns while parked or driving, .......

https://insideevs.com/news/752720/ev-12-vol...ttery-problems/ -
The big, expensive batteries are dead reliable. It's the puny 12-volts that are causing problems. - 6 March 2025
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No, it's very similar lar.

It proves that the 12V battery in EV cars can fail for various abnormal reasons, resulting in car breakdowns while parked or driving, ......

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From my link above, .......

.... Yet the simpler route is not without its pitfalls. EVs from Hyundai, Kia and Genesis don't have the same power management issue as Rivians. They have a much worse physical issue. The Integrated Charging Control Unit (ICCU) that charges the 12-volt batteries in these vehicles is a key failure point. A transistor within the unit can be damaged by overvoltage, making it unable to charge the vehicle's 12-volt battery. When that happens, it's a ticking clock until you lose all 12-volt power. That will lead to a gradual loss of drive power, which the recall notice notes could potentially increase the risk of crashing. Well, multiple recall notices. ...

= a failing 12V battery in a moving EV car can result in loss of drive power, and in the case of the BYD Atto 3 in Malaysia, it resulted in a total loss of drive power (not gradual loss) and immediate braking on the highway = A TERRIFYING SITUATION, ie  12V battery fail ---> door sensors also likely fail ---> falsely sensing as door open while car is moving ---> auto activation of EPB and total power shutdown.
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12V battery fail.

---> door sensors also likely fail -

Didn't your own geekzone forum link stated that there was around 1 BYD Atto 3 breakdown per day due to failed 12V battery caused by long ship-freight of the EV cars from CCP China to NZ.?

Didn't my insideevs link stated that faulty ICCU had caused failure in the 12V battery of Hyundai, Kia and Genesis EV cars which necessitated recalls.? .......

https://insideevs.com/news/752720/ev-12-vol...ttery-problems/ - The big, expensive batteries are dead reliable. It's the puny 12-volts that are causing problems. - 6 March 2025
.... Issues with 12-volt batteries are clear in Consumer Reports' reliability data, Elek said. While the firm couldn't confirm whether 12-volt problems are more common with EVs, it has data showing them as consistent trouble spots for EVs like the Hyundai Ioniq 5, Kia EV6, Rivian R1S and Rivian R1T. Forums for any of those brands support the issue.

Hyundai, Kia and Genesis have all had to recall EVs due to issues with the system that charges the 12-volt battery.  ...

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It's a fact that the 12V battery directly powers the door sensors plus other accessories when the EV car is switched on and/or parked or being driven = if the 12V battery fails, for whatever reason, it's only logical for the door sensors plus other accessories to also fail.
....... It's the same with our mobile smartphone/tablet being directly powered by its 5V battery, eg powering the screen, speakers, microphones, fingerprint sensor, cameras and their sensors, 4G/5G or Wifi connection, GPS, accelerometer+gyroscope, etc = if the 5V battery fails, all the accessories will also fail.

You believe the TERRIFYING SITUATION in the OP (emergency braking from 100km/h in 6s) was caused by the faulty door sensor only, ie not related to a faulty or failing or weak 12V battery. You likely believe wrong.
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Didn't your own geekzone forum link stated that there was around 1 BYD Atto 3 breakdown per day due to failed 12V battery caused by long ship-freight of the EV cars from CCP China to NZ.?

Didn't my insideevs link stated that faulty ICCU had caused failure in the 12V battery of Hyundai, Kia and Genesis EV cars which necessitated recalls.? .......

https://insideevs.com/news/752720/ev-12-vol...ttery-problems/ - The big, expensive batteries are dead reliable. It's the puny 12-volts that are causing problems. - 6 March 2025
.... Issues with 12-volt batteries are clear in Consumer Reports' reliability data, Elek said. While the firm couldn't confirm whether 12-volt problems are more common with EVs, it has data showing them as consistent trouble spots for EVs like the Hyundai Ioniq 5, Kia EV6, Rivian R1S and Rivian R1T. Forums for any of those brands support the issue.

Hyundai, Kia and Genesis have all had to recall EVs due to issues with the system that charges the 12-volt battery.  ...

It's a fact that the 12V battery directly powers the door sensors plus other accessories when the EV car is switched on and/or parked or being driven = if the 12V battery fails, for whatever reason, it's only logical for the door sensors plus other accessories to also fail.
....... It's the same with our mobile smartphone/tablet being directly powered by its 5V battery, eg powering the screen, speakers, microphones, fingerprint sensor, cameras and their sensors, 4G/5G or Wifi connection, GPS, accelerometer+gyroscope, etc = if the 5V battery fails, all the accessories will also fail.

Repeating. Countered.

Yes if you use your critical thinking and common sense, it is also logical that the whole LCD screen all the lights and everything will also fail. Means nothing will turn on. Suddenly only door sensor fail but all the processor , memory , radio system is working .. LOL.
But the LCD screen is still on, the processor is still working.  So your logic fail again. Btw there's no 5V battery , I understand similar to the bozo Catholic guy who claims to know electrical systems, you cannot understand what voltage regulated system means.


.... Original Text:
Pengalaman paling MENGERIKAN bagi kami sekeluarga apabila kereta BYD Atto 3 secara tiba-tiba brek mengejut ketika sedang memandu di lorong kanan lebuhraya!

Pada 1 May lalu, kami dalam perjalanan dari Melaka ingin pulang ke kampung di Penang dan singgah di Kajang sebentar untuk menghadiri rumah terbuka. Sewaktu di lebuhraya Cheras-Kajang, kereta dengan secara tiba-tiba brek mengejut tanpa ada sebarang amaran atau apa-apa 'indicator'. Di skrin panel kereta pula menunjukkan "Power System Failure" dan keempat-empat tayar kereta seperti di kunci.

Beberapa kereta hampir kemalangan kerana mengelak dari merempuh kereta kami yang tiba-tiba berhenti di lorong kanan.

Saya terus menelefon pihak lebuhraya untuk meminta bantuan mengawal lalu lintas. Alhamdulillah, kurang 10 minit pihak peronda sampai dan terus meletakkan kon di lorong kanan agar kenderaan lain berwaspada dengan kereta kami. Saya juga cuba untuk 'Off dan On' kereta namun tidak berhasil kerana tiada sebarang respon. Tayar pula seperti dikunci dan kereta tidak boleh ditolak walaupun gear sudah 'N'.

Dalam 1 jam, pihak towing insurance pun datang dan menunda kereta kami ke pusat servis di BYD Glenmarie Shah Alam. Jam menunjukkan pukul 7 petang dan saya hanya boleh meninggalkan kereta tersebut di situ kerana di luar waktu operasi. Kami sekeluarga terpaksa menumpang di rumah saudara yang terletak tidak jauh dari situ.

Pada keesokan paginya, saya menelefon BYD Glenmarie untuk memberitahu masalah kereta tersebut tetapi mereka memberikan pelbagai alasan seperti, 'tidak cukup staff', 'perlu appointment', dan pelbagai lagi. Disebabkan hal ini 'emergency' kerana melibatkan nyawa, saya tetap menegaskan dan memaksa mereka untuk memeriksa kereta tersebut.

Pada 4 petang mereka memberitahu kereta kami mempunyai masalah bateri 12V dan memerlukan masa beberapa hari untuk membaik pulih dan melakukan pemeriksaan. ...
https://forum.lowyat.net/topic/5521715

In the case of the OP incident above, the 12V battery was weak (10 month old) or failed, not totally failed = still got LCD screen showing "Power System Failure" but all other power-drawing functions no more working.
....... Likely the TERRIFYING  automatic emergency braking from 100km/h in 6s (= Power System Failure) by the computer of the BYD Atto 3 EV car was to pre-empt total 12V battery failure or total accessories failure, eg no power steering, no ABS, no emergency airbags deployment, etc..
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Boy96
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No lah. The running EV car is still running after its 12V battery is removed does not mean the accessories are also still running, eg door system and sensors, lights, etc or such EV car can still be driven on the road.
....... AFAIK, with an EV car running or switched on, the traction battery directly powers the electric (drive) motors, which motors in turn powers the climate control system, eg compressors, ... and recharges the 12V battery when needed, which 12V battery directly powers the accessories, eg door system and sensors, lights, HVAC fan, steering, braking, computer, ADAS, cockpit displays, etc.

Note that the 12V battery also powers the "starter" system, ie it is needed to "wake up" the traction battery's power system, eg a dead 12V battery in a parked EV car that has been switched off = a dead EV car that cannot be started or "woken up" = may need to be jumpstarted or the 12V battery replaced.
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Fyi, .......

https://www.bannerbatterien.com/en/Battery-...board-batteries - EVERYTHING ABOUT THE 12V BATTERY IN THE E-CAR
EXPLAINED QUICKLY AND SIMPLY
.... Another Banner tip: Take the electric or hybrid car to the workshop for service or repair, then please leave at least one side window open in the workshop. Even better: leave a door propped open so that you can get back into the electric car if necessary. Why? Depending on the repair, the 12V starter and on-board battery could be disconnected. If this happens without external voltage maintenance, the doors could remain locked, depending on the car model! In the worst case, the workshop visit will now take a little longer than planned.

This information also applies to DIY (do it yourself) service and repair work. ...

Gemini AI Overview:

Disconnecting the 12V battery while an EV is running can cause various issues, but the car won't immediately stop. The 12V battery primarily powers the car's accessories, electronics, and some auxiliary systems, not the main traction battery that powers the motors.

However, disconnecting it can lead to:
- 1. Loss of Accessory Power: Features like lights, air conditioning, and radio may not function if the 12V battery is disconnected, as they rely on it for power.
- 2. Potential System Errors: Some electronic systems, like the car's computer, may malfunction or display error messages due to the lack of power from the 12V battery.
- 3. Difficulty Re-Starting the Car: The car may not start or have difficulty restarting if the 12V battery is completely depleted.

Important Note: The EV's main traction battery still powers the motors, so the car can continue to drive, albeit potentially with reduced functionality. However, disconnecting the 12V battery while the car is running is generally not recommended, and it's best to address any issues with the 12V battery when the car is off. 
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BYD already sell like what? 10 thousands of cars the past 3 years in Msia?

If a simple 12v battery failure caused this, there should be at least few hundred cases like this have occured 🤔

DC/DC converter kaput could be the main culprit. But it seems to occur very rarely. 12v battery kaput is so common its impossible this thing just happen once in this case.

Machem ICE car yes 12v battery kaput is so common. But alternator that constantly charge the 12v battery kaput we very rarely encoutnered it though it can still happened.

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In this case, ie the BYD Atto 3 suddenly auto emergency braking on the highway from 100km/h in 6s, purportedly due to a faulty door sensor and not a faulty 12V battery, is also scaring consumers from buying BYD EV cars.

If this TERRIFYING or SCARY incident had happened in CCP China, BYD would have already blamed it on the driver by issuing an LOD or lawyer letter to demand the deletion of the post/comment and a public apology from the driver.
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So, why the owner had to drive to the nearest (public EV charging station) location to DC-fast charge his BYD Atto 3 car after jumpstarting the car with a "dead" 12V battery.?

Then afterwards, why the owner could switch off and on the EV car without any issue  after AC-slow charged it at home.?
= the EV car could not start because of a weak or depleted/discharged 12V battery, not bc of a "dead" 12V battery. A  truly dead 12V battery cannot be recharged and the EV car can no longer be started = a dead 12V battery needs to be replaced with a new one, eg a 12V lead-acid battery that has reached it's normal life span of about 2 years.
....... Similarly for our smartphone battery if dead after about 2 years of daily usage.

Similarly for a weak/depleted or a dead 12V lead-acid battery in an automatic petrol or ICE-V car, ie the former can be jumpstarted to start the automatic ICE-V car, whereas the latter can also be jumpstarted to start the car but thereafter it can no longer start the car on its own = needs to be replaced with a new one.
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More like the statements that you made above and in the past  were wrong.
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Your above image states that  the BYD Atto 3 owner's  service advisor from BYD Penang told him that the 12V battery could not be recharged bc each time the HV battery is below 20%, it will not recharge the battery. That was why his EV car could not be started, ie the 12V battery "died" or was discharged/depleted or weak due to not being recharged by the HV battery that was below 20% SoC = had to be jumpstarted.
....... Are you also saying the BYD service advisor is wrong.?

Then the advisor told him to drive to the nearest location and get the car DC charged after jumpstarting the car. Why would the advisor tell him to  fast-fast DC charge the car if the HV battery was recharging the 12V battery  even when the HV battery was below 20%, eg at 5% to 1%.
....... Eg why the advisor did not tell the owner to drive home if it only takes <20% of SoC to do so, and AC slow charge his car at his home.?

I believe you have misinterpreted your own posted image above.
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Your above image states that  the BYD Atto 3 owner's  service advisor from BYD Penang told him that the 12V battery could not be recharged bc each time the HV battery is below 20%, it will not recharge the battery. That was why his EV car could not be started, ie the 12V battery "died" or was discharged/depleted or weak due to not being recharged by the HV battery that was below 20% SoC = had to be jumpstarted.
....... Are you also saying the BYD service advisor is wrong.?

Then the advisor told him to drive to the nearest location and get the car DC charged after jumpstarting the car. Why would the advisor tell him to  fast-fast DC charge the car if the HV battery was recharging the 12V battery  even when the HV battery was below 20%, eg at 5% to 1%.
....... Eg why the advisor did not tell the owner to drive home if it only takes <20% of SoC to do so, and AC slow charge his car at his home.?

I believe you have misinterpreted your own posted image above.
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Because you have to keep the car on while you slow charge to keep the DC/DC converter working.  
If it was above 20% he can off and lock the car and charge.
So are you asking him to leave the car on for 2 hours while he slow charge the main traction battery? 

You believe wrongly.

No, you believe wrongly, .......
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https://www.reddit.com/r/electricvehicles/c...vs_12v_battery/ - r/electricvehicles 1 yr. ago
Positive_Guarantee20

ELI5: Traction battery vs. 12V battery
....
deleted

As a safety measure, all EV cars disconnect the Traction Battery after no usage between 5-10 minutes of isle no powered on state. The 12v passively maintains the car's ECUs at that point.

Therefore, a 12v will only charge from the Traction Battery when the car is operational, as in driving.

lbfb

This isn’t neccacarly true of the Ioniq 5 ( and maybe all E-GMP, but not sure there). The I5 will engage the traction battery to top up the 12V as long as the former is above, I believe, 20% SoC. That’s what the orange light on the dashboard is indicating, that the high voltage system is active.

Likely issue for the OP is that the 12V batteries in some I5s just die eventually. Assuming the vehicle has had all TSBs applied I believe it should be fine once the 12V is replaced. Don’t know if it’s been stated or determined if they’re dying because of something the vehicle is doing or they’re just crap batteries.

retiredminion

Not all EVs. Teslas will keep the low voltage battery refreshed from the traction battery.

I left my 2021 model Y with the older 12v lead acid battery parked and unplugged for 3 weeks and everything was fine when I returned. So too my wife's 2023 model 3 with the 16v lithium low voltage battery. Even most newer ICE cars would have 12v battery problems after being parked for 3 weeks.

retiredminion

Apparently you missed the part that said "... most newer ICE cars ...".

The reason is due to all of the electronics that continuously draw power in newer vehicles. I'm not personally familiar with farm vehicles but I'm guessing they don't generally provide things like keyless entry, remote functions, alarm systems, etc. ....

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NZgeek

In general, it works like this:

The low voltage (usually 12v, but newer Teslas use 48v) battery powers the car's systems when it's not in a ready-to-drive state.

When the car is put into a ready-to-drive state, the high voltage traction battery takes over and an inverter produces the lower voltage needed for the car's systems.

The traction battery is disconnected when it's not needed. This is likely for safety reasons: why expose the car's systems to 400v/800v if it's not being used? The connection/disconnection mechanism typically lives inside the traction battery pack, whereas the inverter to low voltage usually lives outside the battery pack (to help with cooling).

It's fairly common for EVs to monitor the level of the low voltage battery, and to use the traction battery to charge the low voltage battery as needed. The 12v battery is also often charged when the car is charging from the wall.

There usually aren't many parasitic drains on the low voltage battery. The worst drains are usually caused by apps that contact the car, e.g. to get its charge status for a smart charger. This can prevent the car's systems from going into sleep mode, causing it to drain the low voltage battery a lot more than it should.
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lurkingaround claims:- The traction battery recharges the 12V battery "periodically" when the BMS detects low voltage for both parked and driving.

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Isn't the BYD Atto 3 similar to the Hyundai Ioniq 5, in that their traction battery not recharging the 12V battery when the former is below 20% SoC.?

Why quote out-of-context until you believe wrong.?


Remember, in an EV car, the 12V battery directly powers the accessories plus the "starter" system(= to start the traction battery), while the traction battery mainly directly powers the electric (drive) motor and directly recharges the 12V battery when needed.
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Isn't the BYD Atto 3 similar to the Hyundai Ioniq 5, in that their traction battery not recharging the 12V battery when the former is below 20% SoC.?

Remember, in an EV car, the 12V battery directly powers the accessories plus the "starter" system(= to start the traction battery), while the traction battery mainly directly powers the electric (drive) motor and directly recharges the 12V battery when needed.
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