Force "low power mode" on mac When there is less than 5% battery left on a mac, the battery indicator goes red and system performance significantly drops - presumably in an attempt to make that remaining 5% last a little longer. 

Is there a way to manually trigger this, so that the system performance is low (and battery life longer), even when there is plentiful battery? 

This would theoretically be a way of extending the number of hours on a battery beyond the rated amount.
I'm using underclocking app volta, seems to be working so far.