Document and Entity Information - USD ($)
12 Months Ended
Sep. 30, 2016
Dec. 22, 2016
Apr. 02, 2016
Document and Entity Information [Abstract]      
Entity Registrant Name SEVCON, INC.    
Entity Central Index Key 0000825411    
Current Fiscal Year End Date --09-30    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Smaller Reporting Company    
Entity Common Stock, Shares Outstanding   5,341,993  
Entity Public Float     $ 20,910,000
Document Fiscal Year Focus 2016    
Document Fiscal Period Focus FY    
Document Type 10-K    
Amendment Flag false    
Document Period End Date Sep. 30, 2016