Fuse for start battery

Court · Member

Fuse for start battery

Stanley · Guru

Hello Court,

You really don't want a fuse in the main starter cable from the battery. This would have to be about 300 amps or more to cope with the starter load. This will be a big and expensive fuse.

There is a fuse on your engine which is to protect the panel. This is a 40 amp fuse. I suspect that you could put a fuse is the small wire to the starter from the key switch but I think that this will cause more trouble than it is worth.

Stanley

-- Edited by Stanley on Friday 22nd of January 2016 08:15:14 AM

Court · Member

Thanks Stanley,

I know I am not required to have a fuse in the start circuit, it just would be safer, until it blows and I can't start the engine in a dicey situation. My 2 year old engine starts faster than I can get an ammeter reading. I do happen to have a spare 300 Amp fuse, is that big enough, I just want a little fire protection, I don't want it to blow if I have to crank the engine for a few seconds.

I can't find any specifications for the starter motor.

Thanks,

Court

Stanley · Guru

Depending on the size and length of the battery cables and the condition on the terminals and batteries, you could show a draw up to 400 amps.

You may get some useful information at this link http://www.cruisersforum.com/forums/f14/what-size-of-fuse-at-the-battery-42396.html

NeilMcCubbin · Veteran Member

We have a Blue Sea 150 amp circuit breaker beside out battery, which has never popped since we installed our Beta 60

We cannot measure the starting current, because the Beta starts first bang, even in the Arctic without using the glow plug

Our previous Volvo 43 HP engine was reluctant to start, so worked the battery hard, but popped the breaker only once, when the starter motor broke physically and jammed

The Volvo took about 100 amps to start

I like having the breaker because we have about 30 ft total cable run, so shorts are not impossible.

Also, the breaker is a good safety when working on the engine, and is not at all visible, so would make boat theft tough.