Hyundai i20 won't start. All electrics go off when trying to start engine. Tried two batteries (one brand new), also with a Noco boost with no success. Volts shows 12.24v when in car, but 12.55v when battery out of car. Any ideas on the problem? : r/AskMechanics
How to easily replace the battery on a 2014 Hyundai Elantra - YouTube
Signs it's time for a Hyundai i20 battery replacement!