Anyone who has been flying multirotors knows the struggle of keeping batteries charged is real. Whether you're flying with small batteries or monster packs it comes down to charge rate. Most batteries are designed to be charged at 1C. There are endless articles online that talk about this so I will not get into too much detail here. A 1C charge rate generally takes 45 minutes to an hour. If you have a small battery such as 4500mah your 1C charge rate is 4.5 amps. If you have a larger battery like a 16,000mah your 1C charge rate is 16 amps. Generally speaking these two batteries will fully charge in the same amount of time but the larger one will require a lot more power. As you scale up your UAV and batteries you need a lot more power to charge enough batteries in a realistic timeframe. We took this problem to RotorCraftRC and they came up with a 4,000w 4x channel charger. Each channel is capable of delivering 40amps of power. This allows us to charge 8x 20,000mAh batteries in pairs at 1C. To give you an example of how this would work in the field picture this. You have a UAV coming in for a landing. Batteries come off and start a charge. By the time the second flight is done you're first batteries have been on for about 25 minutes. By the time the Third flight is done your first 4 batteries should be topping off. These battery chargers are equipped with a charge controller that uses RFID tags to automatically load the battery settings and then log the charge cycles of each battery. If your battery starts to age past its service life the charger will let you know. All the battery logs can be uploaded to dropbox, monitored on an iOS device and tracked over time to help with fleet management.