battery isolator

I have a 24v battery system in a Toyota Coaster. I wanted a way to isolate the batteries when not using the vehihcle. Used one of these https://www.supercheapauto.com.au/p/sca-sca-battery-terminal-isolator-switch-universal---1-pack/214448.html?cgid=SCA010603 which seemed to work fine. Then all of a sudden the vehicle wouldn't start. After a bit of fiddling found it had cooked itself where it screws down to make contact. Have chucked it and all is now fine. Should that product have done the job. The only load on the batteries while running is a 25 amp dc dc charger, normal deisel motor needs (which I believe is next to nothing) and maybe 10 amps for usb charging, radio etc. I don't know if I got a dud or it wasn't up to the task