Bought years ago + small battery + chronic problem+ short trip + 4 days.
If the battery has been in use for more than 4 years, replace it. If it were me, I'd look through i10 forums and see if someone has been able to install a larger capacity battery without a major modification.
When replacing it have the battery connections to the block and body checked and the primary cable resistance measured and the clamps cleaned.
If the battery is less than 4 years old, my next thought is that your driving habits may not have been fully charging the battery.
Batteries can fail. If lead acid batteries are allowed to discharge they fail faster. If they aren't fully charged on a regular basis, they fail faster.
I would connect the battery to a smart charger, charge it until the charger indicated full charge. Disconnect the charger. Turn the headlamps on for 1 minute, then off. Wait 5 minutes and measure the battery terminal voltage.
Repeat the battery voltage measurement daily and see if it is declining. If so, either you aren't driving far enough between starts or the battery is failing.
With a battery more than 3 years old, I wouldn't worry about drive belts and alternators until I'd eliminated the battery as the problem.