There are two basic types of DC/DC Converter.

A Non-Isolated Converter is the lowest cost approach.  The major characteristic
is that one lead is common with the battery pack.  The SPS Non-Isolated
converter has the +12 V and the B+ (48 or 36 VDC) leads common.  The
Converter develops  36 VDC on the output lead so that the Red lead is 48 VDC
and the Black lead is 36 VDC.  The difference is 12 VDC and all the 12 V loads
perform as normal.

In addition to being the lowest cost, this approach has the advantage of allowing
the key switch (+48/36 VDC) to turn a radio on and off.

An Isolated converter has a transformer between the input (48/36 VDC) and the
output (12 VDC).  This provides galvanic isolation (not physical connection
between input and output).

An Isolated converter should be used when any one of the following is true:

  • The vehicle will be operated in wet, dirty or corrosive (e.g. salty)

  • The installation will be by an end user or a dealer with limited electrical
    experience (not familiar with the difference between isolated and non

  • There is any pack voltage on the frame of the vehicle that can not be

  • There is any+/- 12 VDC connection to frame that can not be corrected

The Installation Instructions for the Non-isolated converter explain how to
determine if there is voltage on the frame or a 12 V connection to frame.


Contact SPS For additional information.
SPS Electronics Incorporated
8005 Island Road - Eden Prairie, MN 55347
Phone: 952.934.7004  Fax: 952.934.8882