Won’t start No Spark.

I’m new to the world of Mopar and also to MSD CDI systems. Are these boxes voltage specific meaning if they have low voltage they won’t work. Reason I ask. The battery was a little low from sitting all winter unattended. After trying to get it running. I had to run an errand with another vehicle meanwhile I had not removed the battery charger from the car. When I returned it started. Thank you for taking the time to reply. Eric.