When the battery pack is more than 4 cell in series, we can use below circuit to provide power supply for MAX17205, it includes 18V Zener, 500kohm resistor, a MOSFET and 1uF capacitor . The 18V Zener will clamp the gate voltage of the MOSFET within 18V. The MOSFET is on and charge the 1uF capacitor as Vgs>Vgs(th) and Vds>Vgs-Vgs(th). When the capacitor voltage reaches about 16V, the MOSFET turns off as Vgs<Vgs(th). The MOSFET will turn on and off to keep the capacitor at about 16V to power the MAX17205.