let dadeFormat = 'YYYY-MM-DD HH:mm:ss'

<RangePicker
   allowClear={false}
   value={activityRange.length == 2 ? [moment(activityRange[0], dateFormat), moment(activityRange[1], dateFormat)] : null}
   onChange={(time, timestring) => {
   		SetActivityRange(timestring)
   }} 
/>