Fig. 7.

Battery runtime. The lifetime and performance of three batteries was assessed by recording light power output at experimental conditions (10 Hz, 100% forward voltage or intensity) until a threshold of $200\mu \mathrm{W}$ was passed. The battery with fewer recharge cycles (1) had a highest initial power output compared to a battery that had recharged 3 (2) or 10+ times (3). During the first 30 min, the power output of all three batteries showed a steady decrease of $\sim 10\%$ for each 10’ of stimulation that was independent of the initial power output. Thereafter, power output declined but remained above 50% of the initial output for 35 min (3) or 50 min (1, 2).