Mega fuse location

About to hook up the Arkpak in the cabin via an isolator and HD dual core (think it's 6B&S ?), Anderson plug input.

Just wanted to check, was going to use 50amp fuse as per Anderson plugs suggested rating.
Do people think that is ok ?
I was going to put this right up as close to the 2nd battery side of the isolator as possible.

Does the other end + near the Arkpak need a second 50amp fuse inline ?
Considering the Arkpak has all it's own protection inbuilt, and not likely to put a surge back the line ??
Why wouldn't the main battery 50amp protect things ?
Or is it the wiring itself you are trying to protect ?

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Yes Les, 50A fuse at the feed end close to the isolator should be fine.
The fuse is to limit the fault current and protect both the cable and the supply (battery).

I believe that the Arkpak incorporates a dc-dc charger and this would prevent feedback from its battery so no fuse would be required at the input to the Arkpak.
If the cable from the cranking battery was connected directly to the auxiliary battery then a fuse at the aux battery end would be required to prevent the aux battery from delivering current to the cable fault.

Ah, if going into the Arkpak via anything but the 12v charger port (ie the 2 terminal posts with wing nuts or Anderson plug) you bypass the smart charger part of the box.
I will fit another 50 amp fuse to that end, just to be sure.
The cable is very tough, the usual dual core thick sheath, and cable tied high above the fuel lines down high along the chassis, so shouldn't be at issue for damage anyway.

I used the same fuse box. It is mounted behind the air cleaner on the R/H side wall of the engine bay. I also mounted three relays for 4WD lights etc near it. That is as close as I could get it to the R/H battery. Yes we split the standard 100 series setup and also added a third to supplement the "accessory" bank. Everything 4WD except the winch comes off the accessory "bank" and there is a Redarc 200 amp isolator in the middle to bring all three to bear as required, such as when winching.

We run two fridges, the compressor, 4WD lighting, internal 12V and USB charging sockets, UHF radio and camping lighting from it.

Phil

Be aware that not all 100s have the alternator connected to the passenger side battery. Depends which year the truck was made.
If you split the batteries (good idea), you'll need to check which one is then the cranker.

Lots of info on LCOOL.org

Yep true mine was on the drivers side and we lengthened the cables to fit alll on the R/H one.

Wasnt hard to do Was on a 2005 TD

Interesting points there, Bantam.

There's no room in the BT50's engine bay for a second battery, so mine is down the back in the canopy. I winch (and, if required, can start) off both batteries. Cabling is 0 gauge and well protected. Considering the max current draw for the winch is around 400 amps, I have allowed for 200 amps in the between-batteries link. (I know it won't get that high because of unequal cable lengths, etc, but that is what I have allowed.)

The 0 gauge cable run between batteries is long and thinking about what could happen in a catastrophy with a dead short I wasn't happy with that not being fuse-protected, so I've installed a 300 amp fuse at each end, close to each battery.

As you say, there will be a mess if one or the other blows, but hopefully if the vehicle is ever a crumpled up wreck there won't be a fire caused by an unfused dead short in that long battery-to-battery link.

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I am with you Frank re: "wasn't happy with that not being fuse-protected" comment.
But I am not convinced about Bantam's 'circuit breakers rather than fuses' for my main runs.
Correctly selected and located fuses do not "make a mess when they blow".

I initially used 60A circuit breakers which had the benefit of providing inherent isolation switches. Two of these were in the engine bay but one failed due to ingress of fine dust so were replaced with HRC type bolt-in fuses enclosed in shrouds. The circuit breakers located in the cabin are OK so far.

Cable protection by shrouding is difficult and probably doubtful if subjected to the extremes of vehicle collision.

Serioulsy there is very good reason, pretty much none of the starter circuits in motor vehicles are fused or have circuit breakers ..... and this goes from motorbikes and buggies thru to heavy earth moving.

As I say once you get over 60 amps you are talking welding currents ........ If you have seen the HRC fuse movie or have seen or seen the results of even fairly modestly large fuse ruptures with high fault currents...... you will understand my comments.

Then start looking at the price of fuses and circuit breakers over 60 amps that are specifically designed for DC ....... remember DC is different to AC in its arcing behaviour ...... so it requires specific devices.

Being uncomfortable or having a desire for protection, simply does not change the facts.

Putting a fuse or breaker in the middle of a cable run between two batteries is pretty much pointless .... it provides pretty much no protection against short circuits to chassis anywhere in the cable run ...... if you have 2 fully charge N70 batteries you have a possible fault current in excess of 500 amps and that is after the CB blows ..... before the CB blows you have possible fault currents in excess of 700 amps continuous..... the 500+ amps cranking capacity of the near battery, pluss the 200 amps thru the circuit breaker.

Even in a single battery situation with 25mm2 cable and a 200 amp circuit breaker the initial fault current will be at least 400 amps for 60 seconds, because most normal circuit breakers and fuses will hold twice their rated current for 60 seconds ...... the reality is that it may well be more ..... that 200 amp breaker ( depending on its spec) may well hold 600 to 800 amps for 15 to 30 seconds.

If you doubt this look at fuse and breaker curves ...... the more current the faster they blow ...... ALL fuses and breakers will carry well in excess of their rated current for extended periods ... how much that excess is depends on the design of the item.

So by the time that 200 amp breaker blows ...... there is very likley to be a big hole in something and a lot of sparks and molten metal.

On heavy cranking circuits, fuses and breakers are so compromised in their function that they are false sense of security and close to being entirely pointless.

We are left with no choice but to rely on nothing but mechanical protection on these heavy circuits.

When you know all this you will realis how poorly protected many vehicles starter circuits are and the possible consequences.

think about it.

cheers

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Bantam,

I'm not sure if your FollowUp 863037 above is directed at me or simply to egotistically impress the general readership.

I sure do not wish to joust with you on matters obviously beyond your training and experience however, for the benefit of readers that could be confused, it should not be left unchallenged.

Suffice to say that much of what you have said is at best, inappropriate, and at worst, nonsense. I am particularly well versed in the application and management of electric current control and in the behaviour of both fuses and circuit breakers, both AC and DC, to very high currents and voltages.

Perhaps my most pertinent experience is the installation and maintenance of a chlorine plant using 60,000 Amps at 180v dc and using HRC fuses in its protection of the rectifiers. The Prospective Fault Current rating of the substation supplying that plant was 350Mva, that is 350 million volt amps protected by 11 kilovolt circuit breakers. So go and deliver your lectures to someone else!

I cannot understand why you raise the 'red herring' of having fuses or circuit breakers in automotive starter motor circuits.......... no-one has suggested such an obviously impractical thing in this Thread.

The same goes for your "Putting a fuse or breaker in the middle of a cable run between two batteries....."
It was not proposed by anyone and your garbage does nothing but to confuse the OP and other readers of this post.

Yet again Alan you judge other peoples motivation by your own standards of behaviour.

I have no need to impress the readership ...... my ego will gain nothing even if I suceeded because most of them of them have no clue who I am.

Yet again it is obvious to me that you have not read and undertsood my entire posts and the very specific circumstances and qualifications they contain.

Time and time again just because someones post follows yours you think it is an attack directed at you ....... remember this is an open forum and a medium for discussion .... not a lecture hall or a project you are managing.... nor is it your private question and answer session.

I don't necessarily direct my comments to anybody in particular but at commonly held beliefs and common practices.

I don't think I am commenting on matters beyond my understanding or experience.

We are not in an industrial context and we are not in a chlorine plant ..... we are talking about relativly simple battery installations in motor vehicles ..... a situation where the realities and practicalities escape many people. ...... many people who should know better.

In particlar we are specifically talking about battery, winching and cranking circuits ...... so the fact that starter circuits are in general not fused is hardly irrelivent or a red herring.

On the matter of putting a fuse in the middle or one end of a run ...... no one may have specifically mentioned this .... but people commonly do it failing to understand the issues.

BTW you are not qualified to comment on what will confuse others ...... again your condecending attitude shows. .... in my experience normal people are much more capable of understanding things than certain qualified engineering types want to believe.

From time to time I become frustrated with the condecending attitude of some on this forum, who are prepared to call people names, disrespect their contribution or dismiss their posts without any helpfull discussion

For this very reason, I and others absent ourselves from this forum for periods of time.

I continue to assert that in high current battery circuits, typically used for cranking or winching, there is little or no meaningfull protection provided by circuit breakers and considerable care should be taken to protect the cabling from mechanical damage and short circuits ..... BECAUSE .... no matter what ..... if a high current fault occurs in this battery cabling the likelyhood of considerable damage and fire is very high

cheers

Alan, I had the pleasure of working for a short time in a chlorine plant at ICI in Sydney. What I can remember is the mercury rolling around the plant floor, walking into a corridor with a big spanner that contained + and - busbars either side, I thought I had broken my arm when the spanner turned because of the magnetic field. Then running like hell when the chorine gas alarm went off.

Got the hell out of there and removed myself from Sydney. Never fitted there anyway. Crossed that culvert over the bore drain called the Sydney Harbour Bridge to where I belonged.

Sorry OP just reminiscing.

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Hi Slowie, I guess that would be the Botany plant? I worked there on construction of the Polypropylene plant but not in the Chlorine plant.Mine was at Dow, Altona Vic.

I witnessed the same spanner/magnetism phenomenon. In fact we covered the steel framework with wooden facings after a fitter walked too close and had a spanner rip off a pocket by magnetism. 60kAmps loop can create quite a Faraday effect.

The mercury in the process was more of a health hazard than the chlorine itself.

Fusable link cable is getting a bit hard to lay hands on these days, two of the major players that used to stock it no longer do .... and in that 20 to 60 amp range mostly it is being replaced with maxi-blade fuses or cartridge fuses ...... or better still DC circuit breakers.

I went looking for Fusable link cable for a repair to a 70 series a couple of years ago ...... and found it a little frustrating to obtain. ..... I installed blade fuses instead.

The other thing is Fusable link cable does not perform as consistently as a blade or cartridge fuse.

cheers

hi
Going thru the rewire for the camper I have fallen over fusable link cable whilist cruising the net ,cant remember where . The electrical wholesalers particularly the leading 2 try to dictate prices and whats available very poor . Any thing unusual they are useless .
There is nothing wrong with fusable link but it can melt other wires around it . Not always run separate to main loom .
I like maxi blades ,the physical terminals grip onto the fuses far tighter than the std blade holder .
The other under used item is a midi fuse holder ,compact and a wide range of ratings . Together it is bolt down protection and has little or no voltage drop .
Comparitive to circuit breakers can have voltage drop and do fail on the odd occasion . Mainly referring to the cheap small busman [stud type, typically steel body] style of circuit breaker.
The larger body circuit breakers are most likely far better .

swampy

A good quality circuit breaker will always perform better than a fuse .... lower voltage drop, better capacity to interupt current ... and resest at the flick ...... BUT like many things in the automotive market, those tin cased breakers are rubbish.

I like blades in general for automotive ..... but the standard blades realy should not be used above 20 amps ...... I have seen 35 amp blade fuses ..... but I am yet to see a standard blade fuse holder rated above 30 amps ... and many of them are only rated to 20 amps.

There are some quite nice maxi blade holders around ..... but even the modest holders are a good item for that 20 pluss amp range.

those following should remember ALWAYS look at the current rating of a fuse holder ..... it may not be up to the capacity of the fuse you want to put in it .... and always stay well within that rating.

There are some other high current fuse holders around .... but they can get a bit pricey and bulky. .... get into that sort of range and the IP rated bakalite bodied circuit breakers I like.

cheers

Bantam, I gotta ask what you base your claim on that a circuit breaker out performs a fuse, or is that a high end breaker will be better than a high end HRC.

If you have a cheap set of side cutters and suitable protection, go and cut a cable connected to an old wire fuse that is in a porcelain fuse holder and then cut the same cable connected to a circuit breaker of the same rating as the fuse (and no not a motor start circuit breaker). See which one blows the biggest hole in your cutters. It will be the circuit breaker.

Ahh well ....... have you seen the HRC fuse movie ...... as apprentices they showed it to us repeatedly.

wire fuses with high fault currents sit there and arc for quite some time, under high voltage and or high current they go off like a bomb.

I have seen and repaired the damage caused by high current failures in wire fuses first hand. ... mind you I have also seen the snot blown out of underspec crappy circuit breakers too.

If you are to compare a modern circuit breaker with a HRC fuse, you would have to consider the fault current inturuption rating of both ....... if like spec was compared with like there would be very little to seperate a HRC fuse and a modern circuit breaker on the matter of fault interuption capacity ....... just circuit breakers have got very much cheaper in the last 20 years.

There are very good reasons why rewirable fuses are illegal in new building work. ... and its been that way for quite some time ... its either HRC type cartridge fuses or circuit breakers.

BUT we are not using HRC fuses in automobiles now are we ...... we are mostly comparing fuse types that are in all intents and purposes a wire fuse, with no specific arc surpression. ... spend right up in the top end you might get an envelope with inert gas ..... but ya spending good to get that

pretty much all the fuses I see used in automotive applications are a pair of fixed terminals with a metalic link between them in normal air......... if that fuse blows at high enough fault current an arc will be drawn untill it is long enough to extinguish its self ...... get just the right fault current and it will just sit there burning an arc for quite some time.

ALL properly designed circuit breakers ... will have a pair of contacts that rapidly seperate to the point where an arc can not be maintained .... the better types will have arc surpression structures around the contact area.

There is simply no comparison between crude wire fuses and modern circuit breakers .... and the entire electrical world knows it.

cheers

On the matter of blowing up pliers ...... not something I make a habbit of and entirely irrelivent.

BUT one thing that might agree with your observations ...... modern circuit breakers have much lower voltage drop than wire fuses ..... particularly near their capacity ....... any fuse is a thin wire bottle kneck in the circuit ...... near their capacity fuses get hot, even glow red ..... this increases their resistance and therefore voltage drop ....... the contacts in a well designed circuit breaker are capable of carrying many times the rated value and if in good condition will maintian a low resistance and thus low voltage drop all the way to their tripping moint