Fusible Link Question

In the main power system of a 1996 XJ, is there only one (1) fusible link? The one off of the power disro to the alt?

Ive been searching and cant find anything on if there are any more, but I did find people debating on what the amp rating is for it, which a diffinitive answer would also be great too. (actually id like to know what the PDC is rated for in the event that I upgrade the alt later)

Sorry to ask such a simple question.

Thanks

Jesse

From what I've seen in later FSM's, the Alternator Output circuit is protected actually within the PDC by a pair of 60A MAXI fuses - making for a total of 120A OEM alternator output before it pops a fuze. There aren't any fusible links - they went out with RENIX controls (I can agree with getting rid of fusible links - I don't agree with eliminating RENIX controls.)

It's possible to simply re-route the alternator output lead through an ANL fuse (or a GBU, or other high-current fuse) and the other side of the fuse can then go to the PDC Input terminal (screwpost with tab on it) or directly to the battery + lead (they're all electrically connected to the PDC Buss bar anyhow) and not have trouble - I need to discern measurements for that myself, so I can offer it as a kit.

Just make sure you select a fuse pattern that will allow for higher than a 120A rating - either singly (preferred) or in parallel (probalby done by ChryCo because it was cheaper than using a single high-current fuse.)

5-90

5-90 said:

From what I've seen in later FSM's, the Alternator Output circuit is protected actually within the PDC by a pair of 60A MAXI fuses - making for a total of 120A OEM alternator output before it pops a fuze. There aren't any fusible links - they went out with RENIX controls (I can agree with getting rid of fusible links - I don't agree with eliminating RENIX controls.)

It's possible to simply re-route the alternator output lead through an ANL fuse (or a GBU, or other high-current fuse) and the other side of the fuse can then go to the PDC Input terminal (screwpost with tab on it) or directly to the battery + lead (they're all electrically connected to the PDC Buss bar anyhow) and not have trouble - I need to discern measurements for that myself, so I can offer it as a kit.

Just make sure you select a fuse pattern that will allow for higher than a 120A rating - either singly (preferred) or in parallel (probalby done by ChryCo because it was cheaper than using a single high-current fuse.)

5-90

Click to expand...

So I can replace the alternator wire with a 4ga. wire with copper lugs, a 120A ANL fuse w/ holder and it will work just fine?

I just want to make sure b/c I am planning on upgrading the charging system in my '00 and this has me a little confused.

Thanks!

Yes, you can replace it with a 4 gage wire (which is good for about 150A on short runs) or 1 AWG (which is good for closer to 350-400A), bypass the PDC entirely, go through an ANL or AGU fuse, and route the other end of the fuse to either the battery + terminal or the PDC input stud.

I've not seen a 120/125A ANL fuse, they go 100A/150A/175A/200A. I haven't checked on AGU fuses, because I don't care for glass tubes (no particular engineering reason - just personal preference.)

Just out of curiousity - have you seen my website? I've got measurements for the mains cables on a 1996XJ/4.0, by the by... There's a link in my sig.

5-90

Yes I did visit your website and it was helpful. Actually they do make a 120A ANL fuse...... 120 ANL

If I can use a 120A fuse with a 4ga. wire, what size fuse do you suggest for a 2ga. wire and a 1ga wire?

thanks.

I'll check out that link.

Size your wire according to anticipated load (granted, my 1AWG cables are overkill - but you can get them in 2/0, which is just ridiculous...) and your fuse according to your anticipated current draw.

With your 126A alternator, you should be fine using a 4AWG (I'd go with at least a 2AWG, but I'm funny that way...) and then select either a 120A or 150A ANL fuse. The fuse is there to protect the rest of your electrics if your alternator "surges" and goes to full output.

Bear in mind that "full output" on an alternator can vary from "rated output" by as much as -5%/+15%, even though is doesn't run at "full output" all the time. With that in mind, I'd think a 120A ANL fuse is a little undersized - OEMR alternators are usually 90A or so, and are fused with a pair of 60A MAXI fuses (making for a total of 120A) - so the OEM's know this as well.

Therefore, I'd go with at least a 2AWG cable, and a 150A ANL fuse.

You can always use a fuse with a LOWER rating than the wire's ampacity, just don't go HIGHER. If you want to stick a 1/10A fuse on 4/0 "entry" cable, go right ahead - but be prepared to answer "Why?" an awful lot...

There should be a chart of ampacities of various wire gage sizes on my site in the Tech section (if not, I need to put it up there.) These listings are for conventional stranded wire - since electricity travels along the SURFACE of a wire strand, they'll be somewhat lower for solid wire (which is rarely used in automotive applications,) and somewhat higher for "welding" cable (which uses a rather finer strand, also making the wire more flexible.) It's rare to find wire larger than about 14AWG in "solid," unless you get AC wiring from an electrician's supply house.

5-90

What would be the appropiate wire to use? Power wire for use in car audio installation or welding wire? Are there any significant adavantages or disadvantages of either one?

BTW-When I clicked on this thread it had 5 replies and 90 views. 5-90 :wierd:

Depends on what you're trying to do.

For typical circuit routing, pretty much any primary wire made by a reputable manufacturer will do - if it's underhood, make sure it's rated for automotive use (which would make it oil- and grease-resistant.) Painless is best by far, but you've got options.

For mains cabling, there are several manufacturers of battery cable (I'd probably stick to a name that is known in the automotive field,) or you can do what I do, and use welding cable. The neoprene insulation used on welding cable is actually MORE resistant to grease, oil, and solvents than the (usually vinyl) automotive insulation, and it offers the additional advantages of greater ampacity for a given gage size, and greater flexibility (both due to the finer strands used.)

"Autosound" wire isn't usually as grease- and oil-resistant as it properly should be, but seems like most of it goes into "kiddie cars" found at shows, and it's run around inside the pax compartment anyhow. I wouldn't use it underhood on a Jeep, that's for certain (unless it said "Monster" or "Belden" on it...)

If you're interested, PM me and I can give you some pointers on mocking up runs, measuring for custom cable cuts, and I can even price out preterminated 1AWG and 4AWG leads for you (I've probably got a kit in 1AWG listed and priced - use the 4AWG for "secondary distribution" - spur posts, amplifier feeds, lighting, whatever. If you're not sure, I can help you with that as well...)

5-90