Usually, batteries that last long also take a long time to recharge. My impression is that the Daisy's battery would be assumed to actively operate for 16 hours per day on 'light duty', with the power armor being hooked up to entirely recharge the power loss in the next 8 hours.
Considering how the Daisy has 168 hours of light duty function in it, each hour of combat likely decreases this by 6 'light duty' hours. Considering how 1 recharge hour recovers 2 'light duty' hours, it'd take 3 recharge hours to recover from 1 hour of heavy combat.
I'd suspect that in the field, provided access to a mobile field base, it'd likely be more advantageous for a Daisy squad expecting heavy action to have spare battery power supplies that their technicians would swap for fresh ones as needed, with the old ones put on chargers.
On Miharu, it's probably not much of a concern. A Daisy that started fighting from the very beginning of Amaya's Gate will probably be able to last until the very end of the mission, seeing how it's doubtful that the entire mission will require 24 continuous hours of continuous active combat.
In Kyou's case, the energy gain to her chosen power armor while hooked up is minimal... but remember that the Daisy's battery doesn't have the power output to make certain high-energy systems function such as the teleportation module, the aether saber-rifle and so forth. However, the capacitors Kyou and Asher are presently using are short supply quick-energy-feed/quick-recharge capacitor reserves, so those benefit from being cabled up and can probably recharge everybit as quickly as the system they usually power (30 seconds to gain a teleport charge, and a pair of capacitor is worth a teleport charge in power).