Ironically - battery is now completely flat it seems, car not react to the remote unlock. I'll check it now, but is it safe to use key to unlock the car? Would it not trigger alarm (I know battery is dead).

Right, things just got 110% more confusing.

Upon unlocking my car with a physical key - alarm immediately blared off, I jumped into the driver's seat to cycle the ignition - and the car started up promptly. Oh well.

I drove off to Tesco to replace the batteries on both of my remotes, result - spare key worked, but the main key does not seem to do anything anyways. So, there's a problem source - it seems like my remote unlock/lock had stopped working on my main key. I'll seek to resolve it with Hyundai.

However, then there is the confusing bit - on my way to Tesco start/stop now started work perfectly well (even with cold engine it'd shut off when in idling in neutral at the lights). I've no idea what's changed.

The "sailing" part does not still work though.

Regarding the battery labels, it's:

60L-DIN 60Ah (20HR) 92RC 12V

CCA (SAE) 44A (EN)

I'd still be keen to replace it, can't take no risks if it fails somewhere far off.

Any advice appreciated.

Ta

Edited by Rudlin on 10/05/2025 at 22:03