You can use the same instance variable in the partials.
Try this,
<%= select :fees_submission, :dates_id, @dates.map { |e| [e.full_name, e.id]},{:prompt => "#{t('select_fee_collection_date')}"},{:onChange => "#{remote_function( :url => {:action => "load_fees_voucher"},:with => "'date='+value+'&batch_id='+#{@batch.id}") }"} %>