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good morning all can anyone recommend a small booster for the 12volt battery if and when it might go flat I don’t want to be caught short and hang around for the recovery service I no this can happen with the Kona electric I just want to be prepared just in case as I do a lot of long trips and just want it for peace of mind any help would be welcome thanks.
 

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Make sure you get one that does NOT have a "battery detector" on it before it will supply power. If the Kona's 12V battery goes flat, it can drop right down to 5V which is below the level that some small battery-pack chargers will connect to. I know this as I had one and it refused to transfer power so I had to return it to Halfords!
 

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Is the 12v battery problem still a problem after the recent software updates? I have noticed that the DCDC charger for the 12v runs every few hours to keep the state of charge up. This is a very definite change in behaviour from before the update.
 

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After my Kona's BMS update 6 weeks ago, I posted that in the first week following, 12v battery SoC ranged from 84-87% exclusively.
Since then, with regular and frequent un-attended charging, the 12v battery SoC has remained above 80%, during both periods of non-use for 3-4 days, and daily runs. The OBD data sender has remained in place from day 1 with no issues; it powers off reliably 30 min after ignition Off. Nothing else is ever left plugged in ...
 

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What can happen? New owner here, what is this, and should I be concerned?
There were recorded issues where the 12v battery would drain when the car is off resulting in the car being unable to start at all. There was a menu item on the instrument cluster called "Aux Battery Saver" that would recharge the 12v from the main battery periodically.

I have never actually encountered this issue but I was aware that it was a possibility.

Since the recent software updates, the battery saver menu option has disappeared and the car now regularly wakes up, charges the 12v battery approximately every 4 to 6 hours.
 

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There were recorded issues where the 12v battery would drain when the car is off resulting in the car being unable to start at all.
Ah, I see. Thanks for this, hopefully I'll never encounter it if the update sorted it :) Thanks!
 

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I have a brand new (well 5 weeks old now) 2020 Premium SE and a couple of weeks after I got it I went to start it after it had been standing for a couple of days only to find the 12v battery completely flat. Checking with a voltmeter it was about 5v. I have a small booster lithium battery pack which started it instantly. I used a regular charger overnight and it's been fine since. Why did it go flat? I still don't know but I suspect the boot wasn't completely closed but I can't be sure. I also can't be sure if the auxiliary battery saver option was active but it is now. Every so often I check the voltage on standby and it's consistently around 12.5v. I'll be getting the BMS update next week so fingers crossed there'll be no more problems but I keep the booster battery in the back just in case.
 

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I have a brand new (well 5 weeks old now) 2020 Premium SE and a couple of weeks after I got it I went to start it after it had been standing for a couple of days only to find the 12v battery completely flat. Checking with a voltmeter it was about 5v. I have a small booster lithium battery pack which started it instantly. I used a regular charger overnight and it's been fine since. Why did it go flat? I still don't know but I suspect the boot wasn't completely closed but I can't be sure. I also can't be sure if the auxiliary battery saver option was active but it is now. Every so often I check the voltage on standby and it's consistently around 12.5v. I'll be getting the BMS update next week so fingers crossed there'll be no more problems but I keep the booster battery in the back just in case.
Tailgate not latched is a classic problem on the Kona. I'm not sure if this problem gets properly fixed with the BMS update, but the update does help with the more aggressive 12v battery maintenance,

Just in case you were wondering how a 5W bulb could kill the battery, the issue is that with the tailgate unlatched at least one of the ECU's remains active drawing down considerable current leading to a dead battery.

Hope this helps

John.
 

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Tailgate not latched is a classic problem on the Kona. I'm not sure if this problem gets properly fixed with the BMS update, but the update does help with the more aggressive 12v battery maintenance,

Just in case you were wondering how a 5W bulb could kill the battery, the issue is that with the tailgate unlatched at least one of the ECU's remains active drawing down considerable current leading to a dead battery.

Hope this helps

John.
Tailgate not latched is a classic problem on the Kona. I'm not sure if this problem gets properly fixed with the BMS update, but the update does help with the more aggressive 12v battery maintenance,

Just in case you were wondering how a 5W bulb could kill the battery, the issue is that with the tailgate unlatched at least one of the ECU's remains active drawing down considerable current leading to a dead battery.

Hope this helps

John.
Mine died at 6 weeks, good bit was AA out within 15 mins although it was 7 am. My car had already had BMS update, still do not know how it happened.

Allan
 

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Is there a simple way the average owner can ( non ODB-dongle ) check the 12v battery level ?
If 10pm on a Sunday eve it's low I know I might do something then + there, to prevent finding few hours later on at 7am it's gone too low.

Actually then second question, if I find it low, do I just turn on ignition for 5mins and it should ( #disclaimer) sort itself out, or for some bizarre reason do I need to drive it , or plug it in , to get the HV-Batt to boost the 12v ?
 

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Is there a simple way the average owner can ( non ODB-dongle ) check the 12v battery level ?
If 10pm on a Sunday eve it's low I know I might do something then + there, to prevent finding few hours later on at 7am it's gone too low.

Actually then second question, if I find it low, do I just turn on ignition for 5mins and it should ( #disclaimer) sort itself out, or for some bizarre reason do I need to drive it , or plug it in , to get the HV-Batt to boost the 12v ?
All you need to do is switch on and leave it on for 20 minutes or so. I see from your signature that you are getting a Kona - If it's new then:-

a) It should have the BMS update and better 12V batterry management.
b) It comes with bluelink where you can check that the tailgate is shut, and also check the 12V battery stsatus!

John.

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If you want to see the actual battery voltage on one of those, make sure you just press the start button without pressing the brake pedal. That way it doesn't start up the high voltage battery and start to charge the 12V battery, which would show you the charging voltage.
 
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My 12v battery has now failed 4 times - twice calling out Hyundai Assist. Last time they diagnosed 0 SOH for the 12v battery - due to the covid situation I had to buy a new battery myself and have only just had the okay to get a refund from Hyundai.

I do now have the "BMS update" so maybe that will fix it ... so hard to tell.

I got one of these Anker PowerCore Jump Starter mini, Jump Starts Cars with up to 2.8L Gasoline Engines, Portable Charger Power Bank, Advanced Safety Protection and Built-In LED Flashlight: Amazon.co.uk: Computers & Accessories ... saved me a couple of times, although I don't think you need much power.
 
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