The response to primary and fragmented lead test beams measured by prototype silicon strip detectors, designed for use in the Heavy Nuclei eXplorer (HNX) and the Trans-Iron Galactic Element Recorder on the International Space Station (TIGERISS) experiments, was evaluated in a CERN test beam in Nov - Dec 2016. The 500 $\mu$m thick, single-sided prototype silicon detectors have 32 DC-coupled strips with 3 mm pitch on the junction side with an approximate $10 \times 10$ cm$^2$ active area. Three different types of electronics were employed to readout the prototype detectors in order to test different read out methodologies, and in each case both the junction and ohmic sides were read out simultaneously. During the test beam runs, the prototype detectors were situated between planar silicon detectors, which provided a comparison of the measured response of each detector. The combined data set shows excellent charge resolution and clearly resolved elemental peaks from carbon (Z=6) through lead (Z=82). A description of the test beam experiments and a discussion of the results are reported.