[Mjl]

I have a 38kwh 2020 and had repeated flat 12v battery in lots of different situations. After trying many things as above, it seemed that the cause was the Bluelink connection to my home charger app / API. The app would request the cars battery status many times when plugged in to determine if it should start charging etc. this woke up the car to check and send the data back. Disconnecting my car from the app fixed the issue.

 

[Mjl]

Hmm. After more than 40k miles with no issues, mine has now died twice this week. First time was when I went to collect it from the dealers, where it had been sat for a week with 10% battery after the most recent firmware update, after which my charge port actuator died and I couldn’t charge. I assumed this was because the main battery was too low to allow the 12v top up to work. However, after several hours of driving since and 90% in the car it was dead this morning. I suspect the battery is now in poor condition after being drained completely, but the booster pack is now back in the glove box and I’ll leave the trim off the handle so I can get in with the key.

 

[Mjl]

Was yours the original battery? If so, after 40k mile and several years, time for a new one anyway I suspect. Hunt around in here for the details of Yuasa that works well. I buy from tayna.co.uk and you might need shims to make the posts up to UK sized ones, if the battery you choose has Japanese (smaller dia) ones.

Not original. This was a warranty replacement after the original was killed by phantom battery drain. Zero problems since then until it was drained down due to car being stuck at less than 10% charge. It was tested at service this week and I was advised it needs replacement. Currently waiting on Hyundai to determine if they will replace as ‘goodwill’. The car will be 5yrs old in September and has now done just under 80k miles. I do seem to be using the warranty a lot though. Am keen to make sure anything covered is sorted before warranty expires this year!