This is on the DC side, right? Fuses are probably the better way to go, relatively easy to change and not all that expensive. 4,000 watts at 24 volts (maybe you might draw your batteries down lower than that and develop higher current) is only 166 amps. Add 50% for the surge, that's your 250 amps. There are two schools of thought here - protect the equipment by fusing at the max draw you want it to ever see, or protect the wiring - fuse to protect the ampacity of the cable and hardware you are using. 400 seems a lot, check out what your wiring can support.
Brian