Fuse on Starter Battery

It started with a thread on the Outbound forum about fuses in general. In that thread there were some valid input about why a fuse on the starter battery makes sense, even though it's not a code requirement. There were good advices in there that we've followed, and documented below.

Here is a really good write-up on why it make sense to have a fuse.

Why (have a fuse on the starter battery)?

Prevent fire, since electrical shorts are probably the number-one cause of fires on boats.

What (are we trying to accomplish)?

  • Put a fuse as close to the battery as possible.

  • Non intrusive installation.

How (did we accomplish our goal)?

Following the advise in the "write-up" above, we installed a Blue Sea battery terminal and a fuse directly on the starter battery positive terminal. To be able to get it to fit, we had to modify the terminal connector slightly to fit the height constraints.

The recommendation is to use a minimum fuse size of 300A for medium sailboat diesel AUX engines 35HP to 60HP. Horizon's engine is 80HP, but since it's turbo-charged it should be as easy to crank as a 60HP engine (that's our assumption, and it works). We use a 300A fuse, which is the largest fuse for the fuse terminal.

Starter Battery Fuse.pptx