Twizy Undervoltage Error

Sounds like a serious case of low voltage! The 'Undervoltage Detected' error is a big clue. An alternator issue is not possible on an electric vehicle, the voltage regulator is integrated in the battery management system, so it's unlikely. Given the symptoms – poor start, system failures, flickering lights – it really points to the battery being heavily discharged or defective. Have you checked the battery's voltage with a multimeter? What voltage does it show when the car is off, and what does it drop to when you try to start it?

Thanks for the quick reply! Okay, battery it is. I haven't checked with a multimeter yet – don't have one handy, I was hoping to avoid buying more tools. Is there a way to rule out a parasitic draw somewhere, even if the battery is on its way out? I'd hate to replace the battery only to have the new one drained by some rogue system. Could it be related to the charging system?

A parasitic draw is possible, but less likely given the age of the car and the sudden onset of the problem. It's more probable the battery's internal resistance has increased due to age and usage, causing the voltage to drop under load. And since it's an electric vehicle the charging system could also be the culprit, but the easiest way is to go to the workshop to replace the battery. I think that would be a good idea to avoid further damage and be safe.

Appreciate the advice! Okay, I'm convinced. I'll bite the bullet and take it to a shop. Turns out you were spot on: battery was toast. New one installed for 290€, and it's running like a champ again. Thanks again!