Set time format 'HH:MM:SS ' for Materialize Clockpicker

I have added below library

<link rel="stylesheet" href="assets/plugins/timepicker/materialize.clockpicker.css"/>
<script src="assets/plugins/timepicker/materialize.clockpicker.js"></script>

With Jquery library .

My input element is

<input id="default_start_time" name="default_start_time" class="timepicker" type="time">

Script Section

$('.timepicker').pickatime({
        default: 'now',
        twelvehour: false, // change to 12 hour AM/PM clock from 24 hour
        donetext: 'OK',
        format:"HH:ii:SS",
        autoclose: false,
        vibrate: true 
    });

Also I have tried

$('.timepicker').pickatime({
        default: 'now',
        twelvehour: false, // change to 12 hour AM/PM clock from 24 hour
        donetext: 'OK',
        format:"HH:MM:SS",
        autoclose: false,
        vibrate: true 
    });

But Time-picker Allows returning hour:min format (Like 08:10, 19:06)

What is the issue ??