Hyundai Coupe Battery Hazard Lights Flash While Charging Car Battery?

Hazard lights flash while charging car battery? - hyundai coupe battery

To make a long story short term:

The battery is empty and try to the battery in my 2002 Hyundai Coupe FX available. Once you unplug the charger, the lights are flashing constantly threatened. I have tried the charger in an old mine Civic made in 1996 and charged as usual.

Why do this? Is this a problem that should be considered irrelevant.

Thanks for any help.