MIDAC Batteries

Hello everyone! I'm having trouble establishing in what year and month my Midac EW100 traction batteries were made. I have this code (339330) which is written on the top of the battery and I don't know how to read it and find out the year and month when they were built. I'm using them on a electric car and by the way they perform, I'm suspecting they're several years older than they should ( and I just bought them in 2013). If someone could help me I would greatly appreciate it Thank you!