Battery drains when ignition is off. (Hyundai i20 2011 1.2L) | The Car Community | Page 1

fringe dock Mar 6, 2026, 8:29 AM

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Im a mechanic apprentice and im unable to figure out where the bettery theif is. The battery drains when the car is compleatly off, i have already checked every single fuse in both the hood fuse box and driver side fuse box. We have also changed the brakelight switch over the pedal.

The first time we checked the fuses it cam up to 0.08+ A on brake lights and on the side mirror folder, but when we checked for this again it was gone, back to normal (0.00A) but we switched the brakelight switch regardless.

It currently goes from 12.3v to 5.3v in 2-3 days of no use and just standing still inside the shop.

What could be wrong with it or what are some things worth checking. I dont know if this is a common issue but if anyone else has seen this before that would help alot

lament ice Mar 6, 2026, 8:46 AM

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How old is the battery?

fringe dock Mar 6, 2026, 10:09 AM

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lament ice How old is the battery?

The battery is only about 2 years old and we have tested the battery, the battery itself isnt the issue

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We have currently plugged out the dynamo to see if its the dynamo diode

modest gull Mar 8, 2026, 2:47 AM

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Does it have any Bluetooth modules or telematic?

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You have to monitor the drain for atleast an hour or more to see how high it drains and when it sleeps

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Could be many things

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Could be a bad input from a module thats causing it to stay awake

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A aftermarket accessory or gps

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Bad ajar switches

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Seat switch, amplifier, radio,

#Battery drains when ignition is off. (Hyundai i20 2011 1.2L)