Suggestion:
1. A solid state relay may be used with the current sensor over the shunt resistor.
2. The current sensor would include another solid state relay that actuates on high battery current that is sensed in terms of higher voltage across the shunt to actuate the solid state relay. The solid state relay would open its contact and interrupt the power solid state relay turn on supply. Then, the power solid state relay would open the battery circuit, thus protecting your load and battery.

You can also use a power MOSFET (HEXFET) instead of relay between negative battery contact and circuit ground. IRF7103 will be good (3A, 50V). I use them as power switches in my circuits. If you want, I'll send you a circuit in ORCAD. micklecat@yahoo.com

you need to define how much current you are going to interupt. because if it is small say under 10 amps you can find a solid state relay to disconnect the battery,or you could look into a more traditional relay config.also you might want to consider isolation of the control ckt
if so a traditional relay ie:drive the coil of it from a mosfet or bipolar and seperate the load current from the control current. if you use a solid state relay you can obtain isolation from an opto-coupler and source the relay control from a second winding from the control ckt power supply