Most fuses and circuit breakers are not rated at 72V DC. The MRBF mentioned above is close, at 58V, and would probably work OK.
I'm new to this...post 2...but I purchased a Midnite Solar MNEPV breaker. I like the idea of making it part of my battery build where it will function as a master OFF switch in addition to providing OCPD service.
See for some explanation of DC circuit breakers:
http://www.midnitesolar.com/pdfs/MidNite_165vdc_ETLtest.pdf