Starter fuse

[Peyton]

Have had two starter fuse holders fail on me in a relatively short period.

It is said that a starter fuse which blows when the car is running can lead to runaway generator/ alternator output which can fry lights, horn, etc. What can counteract this — another fuse location?

Wouldn’t want to install a bunch of fuses on my desirable primitive 6v electrics!

[Synchro909]

What caused the fuse holders to fail? I have written here in the past about how tightening the terminals on them needs to be done with great care.

[Peyton]

I noticed what appeared to be some evidence of a short at one of the fuse posts. There was an obvious short at the holder at my last attempt to install it.

I bought a 30 amp inline watertight fuse holder and will use it if I can figure a way to prevent runaway alternator output in event of a blown fuse.

[katy]

I use this type of fuse holder, works good:

[Bob C]

I believe the runaway problem would only be with a three
brush generator without an electronic voltage regulator.

[rotorwrench]

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A visual check of the holder should tell if it has a loose terminal or wire. In the case of the simplistic model A wiring system, the one fuse protects most of the wiring in the car since it acts as a main power buss fuse with all other circuits following. In later years, Ford started adding fuses for particular circuits but there were no fuses in the model A. If a person looks around at the different sources of these kits on the web, they will find that some are better than others. It would pay to get the best quality kit available or fabricate your own using the best parts available. If a person installs one of these kits and then reconnects the battery into the system and the fuse blows then it's time to look for a short somewhere.

An alternative would be to use a short stop circuit breaker instead of a fuse. At least that way a person wouldn't have to keep replacing fuses till the short is found and repaired. Ford used these for main buss protection up into the 50s. They are still available in multiple amp ratings. Some will plug into a fuse holder.

[mcgarrett]

Originally Posted by katy

I use this type of fuse holder, works good:

I use the modern ATO blade type fuse also. Vibration doesn't affect them, they're water resistant, and if a fuse blows while out on the road, it's easier to find them than the old glass tube style fuses.

https://www.amazon.com/ato-fuse-hold...to+fuse+holder

[Peyton]

I like the modern fuses (C fuses?) also but found the watertight inline glass fuse holder at NAPA — 30 amp with 10 gauge wire.

I run 6v alternator. Would that negate a runaway problem?

[Kurt in NJ]

Originally I thought I needed the starter fuse but when the fuse holder failed is started a fire in the generator,burned out all the bulbs .
I think a better place is at the cutout for the light harness and if you have a dome light a small low amperage fuse for just that wire. — a 30 amps may fuse on the starter may be too large to protect that wire next to the upholstery,the dome light only needs a 2-5 amps may fuse.
I am going to experiment with a generator internal fuse for the fields.

[nkaminar]

Peyton, Polish up the contacts and then sightly squeeze them together. Use some electrical grease when installing the fuse. If the fuse is still not tight in the holder, squeeze the contacts together some more. Even some new fuse holders will not be tight enough.

[Peyton]

Will install the inline watertight fuse that I bought if I find that 6v alternators eliminate runaway.

[Badpuppy]

Originally Posted by Peyton

I run 6v alternator. Would that negate a runaway problem?

Yes. The alternator has an internal regulator.

[Peyton]

Thanks!