A power supply with DC surge and spike protection having additional, optional power conditioning and control functions such as low voltage protection, electro mechanical interferences(EMI) protection and radio frequency interference(RFI) protection. The device is for attachment to vehicular electrical systems for protecting, conditioning or controlling the input power to electrical devices such as computers, audio and video systems, PDA's, wireless phones, and other electronic products. The power supply includes a housing having a male cigarette lighter plug inserted into a vehicular cigarette lighter plug or DC power outlet, electrical circuitry in the housing and one or more female power receptacles into which the powered electrical devices DC connectors are inserted.