I found a workaround by using setCellValueExplicit()
eg:
$sheet->setColumnFormat(array( //se formatea la columna a texto
'C' => PHPExcel_Style_NumberFormat::FORMAT_TEXT,
'I' => 'dd-mm-yyyy hh:mm'
));
$sheet->setCellValueExplicit('C10', $object->card_number, PHPExcel_Cell_DataType::TYPE_STRING);
Hope this helps ;)