Connect fuse directly to battery terminal?

[hedge]

Can I connect a Mega style fuse directly to the battery terminal with the other end connected to the cable with a bolt? If it blows does the fuse stay in one piece?

I installed new batteries and they are taller and I don't have room for my Blue sea terminal fuse mount anymore.

Is this type of catastrophic fuse even necessary? The wire goes directly to a switch and from there to circuit breakers before any loads so it seems to me it should be pretty well protected. It certainly didn't have a fuse in their from the manufacturer.

[hedge]

Well, this is what I came up with so far. It's not pretty and a kluge so not sure I'll leave it this way but that's what I had on hand. I just built a very short cable and used the fuse I was originally using. I still may just remove it as It doesn't come near any metal or anything it could short to.

You can also see the limited space I have to work, it's on a truck camper and the battery box is a side cabinet.

Thanks for the input.

[brulaz]

hedge wrote:

time2roll wrote:

hedge wrote:
Is this type of catastrophic fuse even necessary?

If the wire to the first fuse is in plain sight and reasonably protected there is no reason to add another fuse.

How big is the wire? How many amps of fuse are directly connected?

It's 2/0 wire, max amp draw is probably around 150. It's overkill but my inverter is very picky about low voltage.

OK, the MAXI fuse will not go that high.
But the MEGA fuse that westend pictured will work.
And there's other similar bolt-on, low-profile fuses (AMI, ANL, Class T) with that amperage. But they have different short-circuit speeds. I think BlueSea recommends Class T for inverters as they are fast.
https://www.bluesea.com/products/category/15/Fuses

[time2roll]

hedge wrote:
It's 2/0 wire, max amp draw is probably around 150. It's overkill but my inverter is very picky about low voltage.

With twice the ampacity of the normal max load I would only worry about a fuse if the wire has a chance of a dead short to ground or travels through a blind area unprotected.

[wa8yxm]

The short answer is YES..

But the longer answer is you may not want to

First.. The fuse is not designed for physical loads.. Only electrical loads. a proper fuse holder puts no PHYSICAL stress on the fuse. Thus the fuse may last longer

Second the metal on the fuse terminal is likely DIFFERENT from the battery terminal

Two different metals, Current plus acidic "Water" is ... A bad mix

But you can likely do it and it will work.. May need more maintenance however.,

[hedge]

time2roll wrote:

hedge wrote:
Is this type of catastrophic fuse even necessary?

If the wire to the first fuse is in plain sight and reasonably protected there is no reason to add another fuse.

How big is the wire? How many amps of fuse are directly connected?

It's 2/0 wire, max amp draw is probably around 150. It's overkill but my inverter is very picky about low voltage.

[brulaz]

hedge wrote:
As I said, I have that fuse holder already but don't have the height above the terminal to be able to use it

I would get the MAXI fuse holder with the short leads, as pictured earlier. You can move the holder around and lay it down sideways on top or tuck it besides the battery.

[brulaz]

My trailer was wired similare to the OPs: Unfused wire to the disconnect switch and from there to self-resetting circuit breaker. Quite a distance actually, maybe 6', much of it in the trailer.

So I fused it at the battery.

But I didn't notice that the 12V line emergency brake switch came off the hot side of the disconnect switch. So I accidentally fused that wire as well. A no-no. That's been fixed now.

By the way, I'm now using a MAXI fuse in a BlueSea holder similar to the one pictured above. It can be moved around so it doesn't stick up at all. And the holder's leads are 6 awg so no problem there. I just needed 6 awg butt connectors and shrink wrap.

[time2roll]

hedge wrote:
Is this type of catastrophic fuse even necessary?

If the wire to the first fuse is in plain sight and reasonably protected there is no reason to add another fuse.

How big is the wire? How many amps of fuse are directly connected?

[hedge]

As I said, I have that fuse holder already but don't have the height above the terminal to be able to use it

[time2roll]

There are fuses made to go on the battery terminal.

http://www.genuinedealz.com/marine-electrical-supply/fuses-and-blocks?cat=23

[westend]

Yes, you can and I did that exact thing.



Any time you have wire connected to a power source in a vehicle or trailer, there should be some sort of circuit protection for the wire.

FWIW, I have possibly a similar situation where the converter, inverter, and solar controller have their own circuit protection. I chose to use a 150 Amp mega fuse at the battery's positive (+) post to protect that circuit.

If you are worried about the intrinsic damage from the fuse if it should blow, encase it in some clear shrink wrap or, as Mex advocated once, spray on some urethane crack filler. I don't worry about it since the batteries are in a box and that is a catastrophic fuse.

[hedge]

I must have a terrible way of explaining things as I always seem to send people off on tangents.

I know a switch isn't a fuse, I guess I shouldn't have mentioned the switch. So it's about two feet until it hits the circuit breakers. I use circuit breakers instead of fuses in front of the inverter/charge controller. I am still using the factory circuit breaker for the converter.

I still think I'll try to find a way to make it fused, just rarely see anyone with a fuse at the battery.

[time2roll]

30 amp is easy.



http://www.genuinedealz.com/maxi-fuse-inline-fuse-holder-w-6-awg-leads-up-to-60a

[BFL13]

I think the switch doesn't count. When it is closed it is just more wire that then goes behind a wall off to the converter etc. So IMO you do need a battery fuse close to the pos battery post. A switch is not a fuse.

AFAIK all RVs have a "battery fuse" up by the pos battery post on the wire going back to the converter way back in the RV. (Fuse amps depends on the amps rating of the converter) Not to mention the fuse on the pos wire for the slide (30a on ours), the fuse for the pos wire for the jacks (30 amp on ours), and even the (15 amp on ours) fuse for the pos wire for the LP alarm and radio memory, that all end up on the battery pos..

You are supposed to also have a big fuse on the inverter's pos input wire from the battery, close to the battery. Size of fuse according to inverter's manual.

If you have a big fuse for the inverter, is it ok to just link all the pos wires to that? NO!!!! The idea is to use "buss" rules.

The various wires to the buss (branch wires) each have various size fuses according to the AWG of those branch wires, and the big fat wire from the buss to the battery that takes the total of all those branch wire amps, then has its own big fuse for its own fat AWG.