I would charge tham at 6Amps, let them sit for about 30 seconds and then discharge at 20Amps until they hit 5Volts. Leave the packs to rest for a couple of hours, then repeat the process.
Then you can store them, as is.
When it comes time to run the packs in a car, I charge at 6Amps and run 5 minutes then tray them. It seems OK to run them twice a day but I wouldn't do anymore than that.