which fuses for 100Amp + circuits

[JBE]

Just wondering what kind of fuses people use for 100Amp + circuits like winches?

I've come across these:
http://bluesea.com/category/5/21/productline/128

They will certainly do the job, but the fuses are dear and the whole setup is a far cry from water proof.

Cheers
Joachim

[PacMan]

Hello

I am thinking a 100A fuse dont help you much on a winch.
A winch with a 6hp engine have ~4.5kw.
4.5kw on 12Volt is 375A.

Do you have so long cables to the winch or why do you want to use a fuse?
I dont think a fuse like this will protect your engine. They are to slow.

Chris

[JBE]

Hi PacMan

It's actually for my alternator cable. I upgraded from the flimsy factory 50Amp to a 130Amp rated alternator. Problem is that the alternator cable won't be able to cope with that. So, I decided to run a new 2 gauge cable to the battery and need to put a 130A fuse in.

To answer your question, I always safeguard major electrical devices with a fuse as you can start a nice fire if you short circuit something like a winch.
I'm actually using this kind of fuse for my winch, but I'm wondering if there is anything else out there which is better suited for 4WDs.

Cheers
J

[krusty182]

Most circuits like this people don't worry about putting fuses in. As long as you keep the run short, use the right cable in some convoluted split conduit and fix it so it can't rub through then you should be pretty right. Most starter motor circuits aren't fused.

[JBE]

The wiring diagram shows that everything goes through the fusible link (alternator, starter, regulator; it's directly off the battery plus). If you pull this fuse, everything goes off. I hear what you are saying. I'm just trying to replicate the way the original loom is set up.
The shortest run, I can do is approx 2.4m.

[GeeC]

The wiring diagram shows that everything goes through the fusible link (alternator, starter, regulator; it's directly off the battery plus).

What's the rating of this fusible link?
Is the starter motor run through it, or just the starter solenoid?

[JBE]

Fusible link is 65Amp and as far as I can see. the starter is run through it. It's a GQ TD42.

[brissle]

dont think the starter motor would run through it, draw a far bit more current than that

[JustinW]

Hi all,

Winch draw will vary greatly depending on how much rope/wire is on the drum.

For this its hard to find a fuse that will fully protect the system. In this situation the best fuse to use is one that has multiple blow points depending on current and time.

These are known as powerval fuses. They will instantly blow in the case of a dead short (in the case of a vehicle accident) and have a range of blow points after running a certain amperage for a certain period of time.

Here is a link to the SWE-CHECK's site listing the Powerval fuse - http://www.swecheck.com.au/catalog/a30.pdf

For most low mount winches i would recommend the SWE-POWCAL-5, you can get them from any Battery World store and they are about $30. You will also need a holder for them (SWE-FMG116) which is about $35.

Most people dont bother fusing winch power cables but due to the size and lenght they have the potentail to cause a fire in a accident or short and for that reason spending the extra few dollars is cheap insurance.

Cheers,

Justin

[-Scott-]

In this situation the best fuse to use is one that has multiple blow points depending on current and time.

These are known as powerval fuses. They will instantly blow in the case of a dead short (in the case of a vehicle accident) and have a range of blow points after running a certain amperage for a certain period of time.

They are known as "fuses".

All fuses have an inverse current / time relationship, usually published as trip curves. The larger the current the faster the trip time - it all about heating the fuse element until it melts. A lower current takes longer to heat the element to its melting point. If the current is low enough the fuse can dissipate heat fast enough to avoid melting. The "range" of trip times relates to manufacturing tolerance and ambient conditions (such as temperature).

I don't see anything special about "powerval" fuses. I'm happy to be educated if I've missed something.

[JBE]

Thanks for all the replies. I ended up using this system for my winch circuit:

http://www.whitworths.com.au/main_itemd ... lutePage=1" onclick="window.open(this.href);return false;

I have a 12000lb winch and started using a 100A fuse. It stil hasn't blown after a couple of hard pulls. I'll use this sytem for my alternator cable as well.
The only thing, I don't like about it, is that they are only slash water proof. Might put them in a sealed box.

Cheers
J

[chimpboy]

In what way do you need it to be more waterproof? Just looking at it you could stand there with a hose on it all day and it wouldn't make any difference.

Not that there's anything wrong with a bit of overkill!

[JBE]

I was looking for something like the maxi blade fuses which are fully encapsulated. Overkill: maybe, I have a reputation for that
My only concern with thwe Bluesea fuses was the possibility of short circuit them when pressure washing the engine bay.

[chimpboy]

My only concern with thwe Bluesea fuses was the possibility of short circuit them when pressure washing the engine bay.

You mean shorting them to the body or something? I think that would be doubtful with 12V. I wonder what others think.

[JBE]

My only concern with thwe Bluesea fuses was the possibility of short circuit them when pressure washing the engine bay.

You mean shorting them to the body or something? I think that would be doubtful with 12V. I wonder what others think.

Yes, that was my concern.

[-Scott-]

My only concern with thwe Bluesea fuses was the possibility of short circuit them when pressure washing the engine bay.

You mean shorting them to the body or something? I think that would be doubtful with 12V. I wonder what others think.

Yes, that was my concern.

I would guess that, technically, you could "short" the 12V to earth with water, but I doubt that the current would be significant enough to create major problems.

With 240V, depending on the installation, fault currents can be over 10 000 amps at 240V. That's a lot of power, so even in a very short duration short circuit you can dissipate masses of energy and destroy things.

In a car, with even a "large" 4wd battery, you're not going to see more than 1000A in the absolute worst case. When delivering this much current, much of the 12V will be dissipated across the battery internal resistance, so the "terminal voltage" at these currents is more likely to be 6V (or less?). The worst case short circuit power is much less than in a 240V system, so there's much less potential for damage.

The resistance in a "water short" is also comparatively large, so you're highly unlikely to draw close to the maximum theoretical short circuit current. Guessing again, I would say that such fault currents are likely to heat, but not enough to destroy quickly - any such fault currents are likely to heat the water that is creating the short, and hence "self clear" the fault.

So what? With lots of guessing, and very little evidence, it's not something I've ever worried about, and I don't intend to start worrying now.

Maxi-blades: I did, and I wouldn't do it again. I have one between main battery & dual battery controller. The holder is crap, and I get increased resistance between fuse blades and holder. Not much, but it's all extra resistance between the two batteries, which is contributing to limiting charge current into the second battery. Unfortunately, I haven't found another "maxi fuse" holder which fits nicely into the same spot, so it's in the too hard basket.

[Shadow]

I think TAP water has somewhere between 1k and 5k ohm/cm.

So if the bodywork of your car is say 5mm from the exposed terminal, and had no paint for some reason?, and you hit it with water, it will be at worst case 500ohms.

P=VI I=V/R

0.3watts of power. Wouldnt even warm a flea.

Saltwater on the other hand has about 30ohm/cm
which would be 10watts. Might warm a flea, but not a fly!.

[drivesafe]

You can actually use real world situations to get a fair idea of whether there would be a problem.

How many people have done a deep salt water crossing say going to the cape.

These crossings don’t cause any problems and on two occasions, I’ve seen vehicles totally submerged in creeks and you could see their headlights still on. That’s a lot more water than just washing will produce.

As to the fuse, this suggestion is a bit messy but will easily meet your needs and size of the fuse is easily altered up or down.

Just get a standard 6 way fuse holder, the ones with spade connector on both sides of each individual fuse holder and just solder your cable to all the spade connector on each side and use ordinary blade fuses.

You could then use fuses up 40 amps each giving you a total of 240 amps of protection.

[-Scott-]

Just get a standard 6 way fuse holder, the ones with spade connector on both sides of each individual fuse holder and just solder your cable to all the spade connector on each side and use ordinary blade fuses.

You could then use fuses up 40 amps each giving you a total of 240 amps of protection.

I'd like to watch that overload (low level). Once the first fuse has gone with a low-level load, the load on each fuse will increase as each subsequent fuse blows - so each fuse should blow faster than the previous, in a more spectacular fashion.

I think that could be entertaining.

[drivesafe]

Yep, weakest fuse goes first then the rest follow suit quick time.

I came across this set up in a 1500w inverter. I couldn’t find any external protection or anything recommending some form of protection so I pulled the thing apart and there they were, 4 x 40 amp blade fuses.

A simple but effective way to make as big a fuse as you need.

[JBE]

Wow, you people have put some serious thought into this. I didn't even think of looking at the resistance of water.
I eneded up buying the bluesea maxi fuse because I like it's characteristics.
I'll hopefully put it inthis or the weekend after.

Cheers
J

[chimpboy]

Wow, you people have put some serious thought into this. I didn't even think of looking at the resistance of water.
I eneded up buying the bluesea maxi fuse because I like it's characteristics.
I'll hopefully put it inthis or the weekend after.

We are very weird in this section of the site.

[stuee]

Wow, you people have put some serious thought into this. I didn't even think of looking at the resistance of water.
I eneded up buying the bluesea maxi fuse because I like it's characteristics.
I'll hopefully put it inthis or the weekend after.

We are very weird in this section of the site.

Id say the rest of the site is weird and its quite normal in here

[-Scott-]

We are very weird in this section of the site.

Be honest, chimp. Some of us are very weird in every section of the site.