The battery meter does not turn solid black on the Basic / 1.13 firmware (at least not for me). You should keep the device charged at all times. The batteries don't like being discharged completely. So don't wait until the device tells you to charge.
Similar to a mechanical device that wears out faster with heavy use, so also does the depth of discharge (DoD) determine the cycle count. The smaller the depth of discharge, the longer the battery will last. If at all possible, avoid frequent full discharges and charge more often between uses. If full discharges cannot be avoided, try utilizing a larger battery. Partial discharge on Li-ion is fine; there is no memory and the battery does not need periodic full discharge cycles other than to calibrate the fuel gauge on a smart battery.