I have a viewmodel like so:

data: {
    filters: {
        earliest: '',
        latest: ''
Then I have a toolbar in a grid tied to this model. The toolbar has two 'datefield' fields and I am binding them to the model items.

{ xtype: 'datefield', format: 'm/d/Y H:i:s', editable: true, fieldLabel: 'Earliest', bind: '{filters.earliest}' }
{ xtype: 'datefield', maxValue: new Date(), value: new Date(), format: 'm/d/Y H:i:s', editable: true, fieldLabel: 'Latest', bind: '{filters.latest}' }
I want the 'latest' datefield to have a maxValue of end of day today (i.e. not 00:00:00, but 23:59:59) and this should also be the default value shown in the datefield.
I tried initializing the viewmodel 'filters.latest' to a string like '09/26/2017 23:59:59' (to try), but upon rendering the datefield stays blank.
Furthermore, I am unable to enter anything greater than 00:00:00 of today.

How do I initialize a date in a datefield when binding to viewmodel? AND how do I set maxValue to end of day?