The time these batteries run at thier optimum is fresh off the charger.I time when I will charge the packs according to how many heats I have before my next run.Its takes 2150 seconds to charge my gp3300's at six amps so I see how many heats I have before I run next and start charging accordingly.They come off thecharger usually with 5 minutes of me using them.So if your thinking of using a pack thats been charged the night before.,beware,the won't perform and you will training them to perform poorly and you may lose run time.This is for gp 3300's.