See this?
It takes hundreds of amps to start a vans diesel engine. Thats why it needs a minimum 480A cranking amp rating on the battery according to the vans manufacturer. This one belongs to one of my carers. It had its lights left on all nght and is a winter morning. I jumped it with my chair. So again it takes hundreds of amps to both pull up the dead battery and additionally to start the engine on top. In the past I have measured similar operations and its a strong 200+A to crank in summer. Hell the heater plugs alone take 35A!
But 50A anderson not even warm. And theres 4 here! 100A fuse in loom, no problem. Because the high cranking current does not last long enough to blow the fuse either...
http://www.wheelchairdriver.com/gopro/starter.mp4