Electrical Fuses

[Bob Bidonde]

I do not have any fuses in my Model A's. However, I plan to add inline fuses into their 12V electrical systems. Both of my A's have 60 Amp alternators, so after starting them there is a brief surge of current that rapidly recharges the batteries. My concern is that the surge current, that approaches 30A, will blow any fuses I install. What size fuse will work in the power wire between the alternator and terminal box and also into the wire from the starter switch to the terminal box. Should they be slow-blow fuses?

[Diastole]

Why not use a breaker instead of fuse?
Slow-blow and fast-blow breakers are available of good quality for waterproof DC systems

https://a.co/d/3M5OlbY

They come in 30,A, 40A, 50A, 60A

It would work as a cutoff switch as well as being easier.

Diastole

[Big hammer]

From the starter to terminal box wire size an inline glass fuse to protect the wire, this will also give some alternator protection, if the wire from the alternator shorts to ground that wire becomes the fuse. A fusible link at the alternator would be better choice than a inline glass fuse or a circuit breaker. Size fuses or circuit breakers to provide protection for your wires size, if you have too many accessories that pull more current than the properly sized fuse for the wire size don’t use a higher rated fuse, the wire size now becomes your fuse the entire length of the wire !

[Y-Blockhead]

Originally Posted by Big hammer

From the starter to terminal box wire size an inline glass fuse to protect the wire, this will also give some alternator protection, if the wire from the alternator shorts to ground that wire becomes the fuse. A fusible link at the alternator would be better choice than a inline glass fuse or a circuit breaker. Size fuses or circuit breakers to provide protection for your wires size, if you have too many accessories that pull more current than the properly sized fuse for the wire size don’t use a higher rated fuse, the wire size now becomes your fuse the entire length of the wire !

Ron Francis Wiring sez No, No, No to fusible links.

[nkaminar]

The fused distribution panels used on boats work well and are easy to use. See https://defender.com/en_us/blue-sea-...ith-cover-5035

There are many styles available at different prices.

[Y-Blockhead]

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Originally Posted by nkaminar

The fused distribution panels used on boats work well and are easy to use. See https://defender.com/en_us/blue-sea-...ith-cover-5035

There are many styles available at different prices.

I have a fuse box under my tank on the back side of the junction bux. I also have a 30amp circuit breaker on the main power line and a 20amp circuit breaker on my headlights.

[katy]

Originally Posted by Bob Bidonde

What size fuse will work in the power wire between the alternator and terminal box?

The fuse rating should be about 20% over the output rating of the alternator.

https://alternatorparts.com/should-a...%20240A%20fuse.

[Badpuppy]

Originally Posted by katy

The fuse rating should be about 20% over the output rating of the alternator.

https://alternatorparts.com/should-a...%20240A%20fuse.

If your wiring can handle it.

[Bob Bidonde]

Thanks all for your guidance. Y-Blockhead, your panel is very nice setup. Thanks for sharing it. Katy, thanks for info about sizing fuses.