Electric Starter Fuse?

[morelor]

I just bought an outboard and it’s the first one that I have owned that has electric start. I’m assuming that I should probably have a fuse or breaker?

The info that I have found on the internet seems to indicate that I may be looking at a fuse of around 200 amps but I couldn’t find anything that about my specific starter. I’m guessing that the right fuse size is not only be dependent on the starter draw but also on the length and gauge of the wire running to my battery.

I have 4 gauge wire from the battery that is about 16 – 18ft long. The motor is a 1969 25hp Johnson (25R69D). Any recommendations on what size fuse/breaker to use? Is it even a good idea to have a fuse for the starter?

[RICK EICHRODT]

Check here for your parts for the 1969 Johnson 25. Depending on what kit you have on your motor, there might not be a fuse in the system as the starter will only work for a short time with the push button or key switch if you have one. It was not until there were charging systems on the motors did the use of a 20amp fuse, not a 200, was used and it was a special small fuse of only about 1/2 inch long.

http://www.marineengine.com/parts/johns … &sid=35512

[morelor]

Thanks for the info rickrodt. I don’t think that there is an existing fuse in the system. I just wasn’t sure if it would be wise to add a fuse somewhere in the circuit between the outboard and the battery.

[fleetwin]

I have never seen a large fuse used inline with the main battery positive cable. I don’t know if something like that is actually available or what amperage would be used.
Most of the OMC systems that are fused use a 20 amp fuse in the positive lead that runs from the hot side of the solenoid to the hot side of the key switch. But, as others have said, some of the electric start models/kits have no fuse protection at all. Your engine’s electric start is on the engine so I doubt there is a fuse. It wouldn’t be too tough to add the 20 amp fuse I mentioned if you are concerned.

[phil-b]

The starter on my OMC 18hp ohms out to 0.2 ohms, which suggests an inrush of at least 60A at 12V.
I’ve seen predictions that the sustained current is under 20A.

Searching for discussion on the topic, I thought this was a good page:
http://www.12voltplanet.co.uk/fuses-guide-uses.html
(from the Country that gave us Lucas Electrical)

[morelor]

Thanks for the info everyone! I think that I’m not going to worry about a fuse anymore.

[jeff-register]

Your relay offers protection once it has been deactivated the current is stopped at that point where ever it is mounted.

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