I changed my 12 volt battery 3 weeks ago. Unfortunately I left the dipped light in my Golf 4 over 2 days. The battery was then completely empty. Not even the ignition went on. I couldn’t even charge the battery. The 12 volt battery was not detected. Only when I switched my old battery in parallel was the new empty battery charged. I fully charged the new battery and reinstalled it. Car starts. I also have another 1 volt battery. 2 V battery ordered because I absolutely need the car from Tuesday and I didn’t think that the completely empty battery can recharge. Now I have two questions: Is the battery worn out strongly even though I could recharge it? The battery is practically new. I want to keep the additional 12 V battery as a reserve. How long can a new 12 V battery be stored, which was not “activated” or not installed before it starts to wear out?