I want to add a fusible link to my battery for safety sake

this is an ex racecar
battery is relocated to the front trunk
I have a welding cable routed from the front trunk to the starter
a large diameter cable (3/4 on an inch OD with shielding)

I don't know the gauge off the top of my head, but imagine the long run adds resistance to the process


what size of fusible link should I look for?
and also does anyone have recommendations for a clean install, easy product to give a professional result


thanks for any tips or pointers
brant

I like this company


https://www.bluesea.com/products/category/16/Fuse_Blocks

Also once you figure out what went wrong, like you dropped a test lead to ground, you can replace the fuse. Fusible links, you get to do more than just replace the section. It also makes it a lot easier to get home, you can carry extras in your pocket to make it easier to get home, or at least off the shoulder.

Also can make it a good way to keep your car, just pocket the fuse, its like a battery cut off switch then. Just a little harder to to work with.

BTW, Fusible links can be found at your FLAPs GM used to use them a lot, not sure if they still do or not.

Brant, local to me member, tom, put together a fused system off of the battery for panel Billy that might be what your looking for. Check with either of them.

good info
I will send some PM's

do you think a 30amp fuse or fusible link, will work with a 914 system, and take into account my long wire run...

I was thinking about going with a cartridge style fusible link
like the modern cars use

but I haven't found a simple single receiver/holder yet

something like this:

Time delay fuse sized 1.15 to 1.25 the ampacity of the cable should do.

sounds good
I'll google search
I have no idea what the sizes mean, or any familiarity with time delay units

You can size closer to your load with time delay fuses offering better overcurrent protection of inductive loads. Generally you get better overload and short circuit protection of inductive loads without nuisance opening of rhe fuse. Motors and generators are inductive. In AC circuits, a time delay fuse will hold 500% of its continuous current rating for a minimum of 10 secs. This allows for the initial starting inrush current of an inductive load that can be 4-6 times rating. Different I am sure slightly for DC.

If the load was purely resistive like a heater element, there basically would be no inrush.

But with inductive loads you would have to oversize the fuse so much if it was fast acting, you would sacrifice overload protection for short circuit protection. Time delay or slow blow fuses give you both.

Really really good info!

I'm finding some options on line..

does anyone know what size, or amperage of a fuse would be recommended....


I doubt the car/ignition/stereo pull anything significant

maybe the fan blower, and especially the starter motor should be the most significant.

does anyone know if 30amp, 50 amp, or ? would be best
I'm not finding as many slow burn style options unfortunately

Brant,


Take a look at these Bussman Cooper in line holders for their MAX Automotive Series Fuses.

Click to view attachment

Click to view attachment

Brant, for the 3.0 V6 I'm putting in my 914, I've calculated two 12-ga fusable links (in parallel) from main batt + to starter, and one 18-ga fusable link from main batt + to voltage regulator (internal to alternator).

If I can find my calculations all pass those on also.

For power to the main custom fuseblock (my current 8 cyl build) I will be using a 50 amp fuse, placed 18" from the battery on a (min) 8 ga. Wire.
For the +main power to the starter, I do like the idea of the 3/4" welding cable with a 30 amp. fuse.
I read up on this here on the forum a few months ago...sounds solid+ safe

Any thought to a circuit breaker on either end of your power cable? A lot of high end sound systems run them to protect the system from both sides of the main power cable, you don't have to replace them when a mistake is made and they're great for theft deterrence. And they don't cost very much either!

I'm finding lots of options with circuit breakers and thinking this is worth trying

because my battery cable is so heavy, I'm struggling to find any type of fuse block or circuit breaker with a large post.

I hate the idea of running a small gauge wire to the fuse block and then jumping to a 3/4 inch welding cable for the run to the front trunk

most of the aftermarket options I find have very small mounting posts for the wire or in line fuse... along the lines of a 1/4 inch post....

I see the a stock mitsubishi part that bolts directly onto a battery post, and then has a new battery post size mount for the existing battery cable

but it is a 120 amp fuse and 15+$ to replace... I don't anticipate wanting 120amps.... and its not adjustable as the fusible link is built into the mounting block and not replaceable.

so I think i'll buy a circuit breaker of 30 or 50amps and with the largest mounting post I can find and see what happens.

I wish they made a circuit breaker with a standard battery post size in/out

brant

True... I haven't looked but are there any automotive circuit breakers available? You'd think there would be because they'd be so adaptable for so many applications. If not, maybe an industrial solution would work?

During diagnostics with the ABM I rigged a clip on fuse line with a flip open all weather single fuse block, and added a square fuse 15 AMP. Clipped it on the ground from stud to cable. You can rig a permanent setup quite easily up front....

..........some of the boaters out there may have some creative solutions:

https://www.bluesea.com/products/category/16/Fuse_Blocks

Hey,

They have nice breakers too....

That's what I used on my 76, comes with six connections, so I can carry two spare fuses as well. I never really trusted having those four circuits wound together and clamped onto the positive battery terminal. A simple aluminum bracket attached to the battery hold-down provides the mounting. It's not waterproof, but designed for boats, so it should be somewhat water-resistant. BTW, the big yellow wire goes to the stereo amp in the front trunk, it already had an inline fuse.
Click to view attachment

nice....

Ditto. Sometime back someone posted a setup that included a fusable break for main power from the battery. I'll dig around in my links to see if I can find. Looked interesting, and was a clean install also.

Edit: Found it. Tom worked up fusable block kit for the red wires off battery. Hope its still available.

Very cool. I like the simplicity.