If your 3S 3200mAh batt pack has a high enough current rating for the 25e setup, you can use it. You'll just have shorter fight times than with the 4400mAh pack. If you have several 3S 3200mAh packs, you can buy or make a parallel adapter that will let you run two of your 3S 3200mAh packs in parallel, effectively making a 3S2P 6400mAh pack. That will also double your current rating compared to a single 3S 3200mAh pack.