Upgrading Electrical

So I want to run something by you guys to see if I am even close to being on the right track. Or if my XJ will burst into flames. '00 with an automatic and 4.0 by the way.

So the goal is to upgrade the alternator. Got a guy, does this for a living, who says he can take a stock alt and maybe get as much as 150 amps out of her. I want a straight bolt in. That is why I am not doing the GC one that guys do.

So figure I will run 4 or 2 gauge battery cables depending on where we end up amp wise. My understanding is that 150 amps and down I can get away with 4 gauge. Anything above that should go with 2 gauge.

We sell everything I need to make battery cables at the Napa I work at. My old boss use to make battery cables for customers. Says we can whack them out like nothing. If I don't do that I am going to go with XJwonders.

So you get rid of the fusible link with something like this:

https://www.amazon.com/Woljay-Bolt-...pID=51iXp7lyJ9L&preST=_SY300_QL70_&dpSrc=srch


I want to set it up in front of the fuse box in the engine compartment like I see other guys do. My understanding is that you use a fuse 25 amps higher then your alt puts out. Figure some military terminals and should be good to go.

At the moment all I am running is factory fog lights but the Jeep did not come with them. So I am using a fuse tap in the fuse box in the footwell for a 12 volt run source for the switch, have the relay by my cruise control with a 20 amp fuse using an inline fuse holder to the battery.

I want to wire in an Ext Idle switch, might want to put lights on the brush guard that I hope to get installed some year, maybe some lights in the back, install the headlight harness I have (purchase from jhc7399), and install one of those retractable under the hood lights I picked up awhile back.

So instead of having a rats nest of inline fuses, trying to fit things by the cruise control near the battery (you all know how tight it already is there), relays scattered all over the place not to mention fuse taps for 12 volt run sources for switches figure I would try to set up an aux fuse box and put all the relays in one place. Oh by the way want to use factory fog light switches for the lights front and back. At the moment thinking in the space over by the power brake booster.

I have read that it is best to put the aux fuse box as close to the battery as possible. So I am wondering if over by the power brake booster is a good idea. No matter what gauge I run for battery cables thinking that one should be 2 gauge.

So I figure between all the relays I figure 4 20, maybe 30, amp fuses. Then 4 10 amp fuses for 12 volt run sources for switches plus what ever amp I will use with the under the hood light. It has a built in switch and will not need a relay. At least I am pretty sure.

So that puts me over 100 amps which seems to be the limit for most aux fuse boxes. Except this one:

https://www.amazon.com/gp/product/B07CLS96RD/ref=ox_sc_act_title_2?smid=A1EQP448COWZL4&psc=1


But this will require 2 cables from the battery cause it is really 2 100 amp max fuse boxes in one. I am thinking I should put one of those circuit breakers in front of that fuse box.

https://www.amazon.com/gp/product/B079GQ5H6F/ref=ox_sc_act_title_1?smid=AH1IN68PWF3TU&psc=1


So I am thinking I run one cable to the circuit breaker and 2 short 2 gauge cables off that to the fuse box. Any idea how many amp that circuit breaker should be?

Then there is the jhc7399 headlight harness. I want to rewire it. Make the wires longer so all that can go with where the rest of the relays and aux fuse box end up. Think I found all the locking terminals I need to rewire the headlight harness.

https://easternbeaver.com/Main/Elec__Products/Terminals/Open_Barrel/187open_barrel.html

I would use the biggest gauge wire I could when I do this. Anybody think this will negate the performance of the headlight harness?

I also want to use some of that braiding that you see on the battery cables. Something like this in the appropriate size.

https://www.summitracing.com/parts/...MIqcui9LT32wIVArnACh1hPAFNEAQYASABEgKkTfD_BwE

Not to mention all ends would have heat shrink on them.

So I think I touched on everything.

So am I clueless or at least in the parking lot at the ballpark? LOL. Be honest. I can take it. LOL. I want to do this right and electrical is not one of my strong points.

Sorry I am kind of all over the place with the post and looking forward to any and all opinions, ideas, etc.

Check out waytek.com -- they'll have all the parts your looking for in 1 place at about the best pricing you'll find

http://www.waytekwire.com *

I've used a power steering pump pressure switch connection for extended idle before, but it'll eventually light the MIL. Pretty sure the pin will be there on the ECM in absence of the power steering switch.

Unless you plan to be running whatever it is you need the added amps for through the power distribution box you dont need to run a bigger fuse than the rating of the fusible link you will be removing from the system. Just because its a bigger alt doesn't mean more amps will be going to the "PDB". Thats only if you add more draw items over stock. Adding a bigger fuse means the PDB will need more amps to blow it and by that time its prob been so hot that it melted something inside the box. Not saying upgrading the wire is a bad thing. Some wire is to close to the line or even undersized but most of us the jeeps are old and the wire has some sort of corrosion and could use some replacing.

Mach2nh said:

Unless you plan to be running whatever it is you need the added amps for through the power distribution box you dont need to run a bigger fuse than the rating of the fusible link you will be removing from the system. Just because its a bigger alt doesn't mean more amps will be going to the "PDB". Thats only if you add more draw items over stock. Adding a bigger fuse means the PDB will need more amps to blow it and by that time its prob been so hot that it melted something inside the box. Not saying upgrading the wire is a bad thing. Some wire is to close to the line or even undersized but most of us the jeeps are old and the wire has some sort of corrosion and could use some replacing.

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Oh and the very best place to add or even have a fuse is as close to the power source as possible. Say you upgrade that 8ga wire going to the PDB with say 6 or 4 but the fuse is at the PDB. That means if you short out somewhere between the two points you will have a arcing heavy gauge wire. If you are lucky it will shut the jeep off and raise alarm to a problem. The other side of the coin is the wire starts a fire.

Minor point - you want the fuse to be rated for 125% (or close - they don't make 146 amp fuses, for example) of alternator output rating, not 25 amps more. This results in the alternator max output being 80% of the fuse rating.

So:
- 90 amp (low spec stock) alt, you want a 120 amp fuse.
- 117 amp (stock) alt, you want a 150 amp fuse. They use a big green fusible link from the factory, it's actually the only fusible link in 96-01 OBD2 XJs.
- 136 amp alt, you want a 175 amp fuse.
- 150 amp alt, you want a 188 amp fuse but they don't make those. I'd probably actually stick on the conservative side for this and use a 175 amp fuse here as well (so yeah, 25 amps over in this case) because a 200 amp fuse is a big jump.

91-95 they actually used two 60A maxifuses in parallel. Pretty ghetto if you ask me... thanks early 90s Chrysler engineers! Technically this means if you got the 117A alternator you were at 100% of fuse rating instead of 80%, but it doesn't seem they cared. 96-01 the fusible link was used instead so they didn't really have a fuse rating. Fusible links are chosen to be 4 wire gauges smaller than the wire they protect so they melt first, rather than by amp rating.

kastein said:

Fusible links are chosen to be 4 wire gauges smaller than the wire they protect so they melt first, rather than by amp rating.

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There's actually a formula for calculating the length of link wire but my meager mind never properly absorbed that information.