Well I guess I answered somewhere else!

This shows you how to calculate the number of SOQL for batch apex and insert the same in a custom object 

• If you want to insert info about each batch

global class MyBatch implements Database.Batchable<sObject>{
 
   global MyBatch(){
        
   }

   global Database.QueryLocator start(Database.BatchableContext BC){
      return Database.getQueryLocator('Your Query');
   }

   global void execute(Database.BatchableContext BC, 
                       List<Sobject> scope){
   
     //Should be the last line
     MyCustomObject__C obj = new MyCustomObject__c(Name='My-Batch',SOQL__c=Limits.getQueries());
     insert obj;
   }

   global void finish(Database.BatchableContext BC){
       
   }

}

• Now say you want to record the number of queries for whole batch process(since a batch is broken into smaller batch of 200 each)

global class MyBatch implements Database.Batchable<sObject>,Database.statefull{
   private static Integer queryCount = 0;
   global MyBatch(){
        
   }

   global Database.QueryLocator start(Database.BatchableContext BC){
      return Database.getQueryLocator('Your Query');
   }

   global void execute(Database.BatchableContext BC, 
                       List<Sobject> scope){
   //should be the last line 
    queryCount = queryCount + Limits.getQueries();
     
   }

   global void finish(Database.BatchableContext BC){
        
    MyCustomObject__C obj = new MyCustomObject__c(Name='My-Batch',SOQL__c=queryCount); 
    insert obj;
   }

}