Yep had it on our old car, and the 12v battery was replaced shortly afterwards under warranty, and on the new car got it after 10 days and they replaced the battery as a precaution, been fine since fingers crossed.

Its the sign your 12v has drained to last knockings before dying. Could be a faulty 12v or something like a boot or door not shut fully keeping a computer awake.

 

But I had my battery replaced 6 months ago. Agrhhhhh!
I can't believe it is happening again

 

Could the boot have been ajar, or something else that has drained it.... Make sure your jump leads are handy, its going to get colder soon!!!!

 

Touch wood, my 12v battery which was replaced 9 months ago is behaving, or rather the rest of the car is behaving to keep it topped up. I did use a conditioning trickle charger weekly on the new battery back in January and again during lockdown in April. Hopefully that helped the new battery bed down. What else can you realistically do?

 

My Kona is in for repairs after a rear end shunt. The Bluelink app alerted me over the weekend that the tailgate was left open and the doors unlocked. When I checked the app, the 12V battery was showing "caution". I've just phoned the garage to alert them to put the battery on trickle charge.

 

Just had a call from the repair shop asking for the granny charger because the car is dead! The traction battery is at 75%, so I think we can guess what's happened. I reminded them that I phoned 2 weeks ago to warn them that the 12 volt battery was low. I've told them that they will have to replace the 12 volt battery now.

 

In the e-Niro forum people have established (actually, @KiwiME who drives a Kona) that setting the car to Utility mode effectively charges the 12V battery from the traction battery. So instead of trickle charging, setting that mode for a couple of hours would likely have the same result.

 

Mine's failed 5 times including once since all the updates were done - it's not going to go away until Hyundai admit there's a problem and do another update to fix it.

I tried running Utility mode for 6 hours last year after the first time the 12V failed and it made no difference; if it's going to go flat, it will go flat, no matter what state of charge it's in because the current drain is so high when it doesn't shut down properly.

 

With interest I follow the 12volt battery forum because my 2019 Kona Electric is now nearly 15 months old. To date I have not had a 12volt battery problem. Only once, I saw the charging light on in the grill centre and clicked the bonnet and tested the charge rate with a DC clamp meter which was a bit over 2 amps current flow. My battery is a rocket brand CMF 45L - DIN..45AH (20Hr rate) CCA (cold crank amps) 410 amps. My understanding is that the CMF stands for "complete maintenance free" .Because the battery has a CCA rating the plates are thin so that they do not heat up quickly during cranking. Because the Kona Electric does not require a CCA rate I would suggest this battery is an incorrect choice for the Kona Electric. An ICE car has an alternator which initially charges the battery at maybe 30 to 50 amps more or less. Stratification of the sulfuric acid in lead acid batteries needs to be considered. Stratification is when the lower electrolyte is a different strength acid to the higher level electrolyte. Stratification can cause loss of battery capacity and premature battery failure. To overcome stratification the technology depends on the bubbling of the electrolyte when charging to mix the acid. The minimum charge rate of a flooded battery is very important for this reason. A better choice 12v battery for an electric car would be an AGM (adsorbed glass matt) battery. The AGM battery does not have a stratification problem and most are deep cycle with thicker plates although some do have a crank rate. The AGM battery should be charged at 6% to 12% of the 20 hour rate and not discharged below 50% capacity at the recommended discharge rate, for good life expectancy.. Some batteries are calcium batteries that need to be charged at a higher voltage, and some chargers have a calcium setting. If we could find some information on the charging parameters of the 12Volt battery charging system in the Kona Electric it would be a good study.
Regards David

 

I believe this battery is a Calcium battery; certainly when I monitor the 12V via the accessory socket, it shows 14.5-15.0V, which is a higher voltage as you say.

For reference, some other EVs / range-extended EVs such as (my old) Ampera had an AGM battery for exactly the reasons you've given.

 

Yep but dealers never listen to owners. They assume we know nothing and will just be annoying. Sadly for most dealers, customers are just a nuisance, particularly the ones who know what they're talking about.