How do I start auto increment from a specific point?

ALTER TABLE batchinfo AUTO_INCREMENT = 20000;

See also Autoincrement

See the last line of your query:

AUTO_INCREMENT=15034

Change it to:

AUTO_INCREMENT=20000

Easy as that! :)

CREATE TABLE `batchinfo` (
  `rowid` int(11) NOT NULL AUTO_INCREMENT,
  `datapath` mediumtext,
  `analysistime` varchar(50) DEFAULT NULL,
  `reporttime` varchar(50) DEFAULT NULL,
  `lastcalib` varchar(50) DEFAULT NULL,
  `analystname` varchar(150) DEFAULT NULL,
  `reportname` varchar(150) DEFAULT NULL,
  `batchstate` varchar(150) DEFAULT NULL,
  `instrument` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`rowid`),
  UNIQUE KEY `rowid_UNIQUE` (`rowid`)
) ENGINE=InnoDB AUTO_INCREMENT=20000 DEFAULT CHARSET=latin1;

INSERT INTO batchinfo (datapath) values('test');
SELECT * FROM batchinfo;