The amount of total Energy meter you have and how fast it recharges depends on what from the Assembly you have equipped on your mech.

Source: https://screenrant.com/armored-core-6-how-to-beat-strider-boss/

The cumulative effect would be that groundwater flow volume that recharges the Sepik River System would dwindle in time, resulting in lower water levels with consequential effects.

Source: https://www.postcourier.com.pg/the-garden-in-the-river/

The website says it fully recharges after 90 minutes.

Source: https://technology.inquirer.net/125313/moonwalkers-ai-shoes