83 Crossfire TA

iTrader: (2)

Almost every fuel pump hot wire kit is set up to connect straight to the BAT terminal on the alternator. Is there truly an advantage to that if your BAT to battery + wire is big enough? Does the BAT terminal to battery + need a fuse/fusible link?

What I have now:

• Stock battery + to BAT terminal wire (it looks like 10-12awg, I don't know if it has a fusible link in it)
• upgraded to bigger 140A CS144 alternator (stock is a 105A CS130)
• Fuel pump hotwire: 8awg wire with a fuse inline connected from the Alt BAT stud to the fuel pump relay at the fuel tank (this actually runs right by the battery)

What I'm thinking:

• Cut the fuel pump hotwire and connect straight to the battery + removing about 4' of wire (keeping the inline fuse)
• Remove stock battery + to BAT wire, replace with 4awg, no fuse/fusible link
• I don't see the point in a fuse in the wire from the battery to alternator, it would run along the battery to starter wire (it runs right past the alternator) just be about 2-3' shorter, I believe the same gauge. If anything the starter wire is more of a fire hazard than the alternator one.
• this gets rid of 4' of wire immediately, 8-9' with the stuff I'm thinking about adding, and ends up making the battery + a distribution block and adds a sufficient connection for the full output of the alternator (I doubt the stock 10-12awg is sufficient to take the full 140A of the alternator for any length of time without at least getting warm, and the FP hotwire isn't taking that much load off of the rest of the harness)
• I probably should double check that there is at least 1 engine to chassis and chassis to battery ground around 4awg while I'm at it.

83 Crossfire TA

iTrader: (2)

Huh, looking at this:
http://www.offroaders.com/technical/...gauge-to-amps/

It looks like 8awg might be enough for the charge wire... strace car with a lot of electronics... but seems to be doing OK with the little tiny wire, to I go 8awg (which I have plenty of) to save some weight or do I find some 6 or 4awg if I do this?

83 Crossfire TA

iTrader: (2)

Anyone?

OrangeBird

iTrader: (1)

Your post has many things going on , but I'll try to answer some of the biggies ;

#1 , Always fuse everything , no matter how short the wire run , the diodes in your alternator can go shorted and alternator fires sometimes become whole car fires .

#2 , Always run the thickest wire you can afford , without regard to weight , the weight difference between 10 and 8 gauge isn't enough to worry about in the short runs of it you'll be using .

#3 , Personally , I don't like the idea of using the back of the alternator as a handy tie point for other electronics . Sure , it's handy , but my preference goes to an independent power block terminal mounted near and connected to the battery with all electronics connected right there . Again , with the wires as short and as thick as practicality allows .

Tibo

iTrader: (15)

I used a 2 gauge on mine for the charge wire. It, along with the sense wire, goes to a power distribution block. I have a trunk mounted battery so mine is setup slightly different than a front mounted. You shouldn't be adding any accessories onto the back of the alternator, instead you should be using the power distribution point (that the alternator sense wire goes to) so the alternator can correctly gauge the instant electrical requirement. If your battery is up front then a 4 gauge should be sufficient but if it is a relocated battery in the trunk I would go with a 2 gauge. Here is a good chart for gauge size vs length vs amp carrying capacity:



Unless it's a big power hog nothing should be ran straight off the battery.

You can run a cheap little inline fuse from a power distribution point easily. I'm not a fan of fusible links unless it's a larger wire (at least 10 gauge) and there isn't room to put a fuse or in case the wire may have short amp spikes that would pop a fuse. Like why they used circuit breakers on the power windows.

3.4 grape

iTrader: (1)

The hot wire is connected to the back of the alternator to pick up the full voltage produced which should be about 14.3 volts. Voltage at the battery terminal is usually lower about 13.5 volts which can vary when headlights,blower motor,etc, are on. Connected directly at the alternator terminal guarantees full voltage no madder what is being used. Check your output with a volt meter.

83 Crossfire TA

iTrader: (2)

LOL, I gave up figuring that I wasn't going to get any answers and then you guys started posting...

83 Crossfire TA

iTrader: (2)

Huh, looking around I can't come up with one example of a BAT charging wire being fused, or the starter wire that runs the same way and is MUCH heavier gauge. Honestly I've seen more electrical failures with starters, and I've never seen either start a fire. Maybe I'm wrong. (This reminds me that I still need to replace my small fire extingquisher that I used to keep in my project car).

What kind of a fuse/fuse holder would you run in a 4awg wire in that connection?

10 and 8awg for a few feet I would agree with, going from the factory metric 2gauge (looks to be about 14awg) to 4awg is a big difference in weight, and I figure anything is an improvement from what is there

I get why the fuel pump hot wire kits do it, but I agree, it's not a good distribution point and I'm not excited by it, which since I've upgraded the alternator and am looking to upgrade the charge wire I don't see much of a reason to keep it.

Do you have a suggestion about a power distribution block? I liked the setup my 4th gen had with one, but I haven't seen much that's easily available outside of the car audio ones that mount to a top terminal on a battery and that is not an option (I'm running a little tiny battery that uses 6 or 8mm bolts for the terminals), so something "remote" mounted on the strut tower would be nice.

What's wrong with using the battery positive as a power distribution point? Looks like the car audio world does that all the time with some crazy setups.

I'm not sure what to do with the sense wire, or with your information there.

Most of my wiring harness is factory, and it looks like the factory distribution point and where the sense wire runs to is the big stud on the starter, and none of that has been moved on my car. The factory charging wire runs to the battery positive, so assuming it's big enough that's as good a location for the fuel pump "hotwire" as the alternator terminal (I feel it's a better location WRT to safety, wire runs/clutter...)

I already have have a 8awg amplifier wire (small 600watt, legit 240watt rms sub amp) and and a 12awg igition box power wire, both with inline fuses already run to the battery positive (the amp wire is the standard setup, the ignition box by the manufacturor's recommendation "to prevent the possibility of problems"), and other electronics recommend that also (one that stands out off the top of my head is that Megasquirt recommends it, and I'm pretty sure that the factory ECM actually takes a separate feed with an inline fuse off of the battery positive (I'd have to look, but I'm pretty sure that the ECM feed is there).

I'm not sure what problem adding one more circuit (the pump circuit) to that point will cause.

That and you seem to contradict yourself in your reply basically saying that everything should be run to a distribution block that the sense wire is connected to so that the alternator can react to changes in power draw except "a big power hog" could be hooked to the battery. Huh?

1- that's what I'm doing with anything that is wired straight to the battery positive, I'm running an inline fuse, and as I noted, so did the factory. The exception that I know of are the starter wire (which I believe is 2awg) and the alterntor carge wire/BAT terminal wire (which I'm talking about upgrading to 4awg

I fully understand this. My fuel pump "hotwire" is an 8awg wire with a 40A inline fuse (it used to be a 30A till I blew it 2x leaving me stranded on the side of the road). If I replace the stock 2 metric gauge (roughly 14awg) wire going from the BAT terminal to the battery positive with a 4awg wire about 4' long, I don't see why the power at the battery terminal would be any significant amount lower than at the alternator.

83 Crossfire TA

iTrader: (2)

Honestly, this is a bit frustrating.

I understand how the sense circuit works and why it would be better to have all the power for the whole car coming from one distribution block, but that's not a very likely setup. The one good thing about the items that i'm considering wiring to the battery terminal is that they're always on and shouldn't be changing usage much (with the exception of the sub amplifier). Things like my radiator fans that will pull a lot of amps and switch on and off are still wired to the distribution point at the starter with the sense wire.

I believe that this is exactly how the 4th gens are wired but I'd have to confirm, with both a power distribution block next to the battery on the inner fender and separate distribution at the starter.

I understand the advantages of putting a fuse in the connection from the battery to the BAT terminal on the alternator, and I also can't find an example of it being done from the factory and don't see it done on any 'Big 3' upgrade kits because I believe that it would be very likely to repeatedly blow that fuse, which would leave you stranded needing a large, not commonly available fuse, and you wouldn't even know that the fuse blew for a while after it did.

DynoDave43

iTrader: (11)

"Do you have a suggestion about a power distribution block?"

I know this wasn't directed at me, but FYI....I like the little factory one used on the L03 cars. You can see mine here.

https://www.thirdgen.org/forums/memb...ml#post6029362

Tibo

iTrader: (15)

Look at the various setups that Blue Sea Systems offers. Lots quality options that they offer.

scooter

iTrader: (11)

When I did my LS swap I bought one of these for the fans and fuel pump relay, and I used the main stud as my distribution block. I got an over sized nylon washer and acorn nut to put over the tops of all the posts to give everything a little protection from accidental contact.

https://www.waytekwire.com/item/4609...e-Module-60A-/

OrangeBird

iTrader: (1)

Thank You DynoDave43 , That's the terminal block I was thinking of .

Oh , and sorry Mark , when I mentioned "fuse everything" I guess I shoulda added the "except the starter" part , but since I've never seen a starter fused I took it for granted that you'd know I meant "fuse everything except the starter" .

That'd have to be one BIG fuse

83 Crossfire TA

iTrader: (2)

I just ordered one of these (a 4th gen junction block):
https://www.ebay.com/itm/381931752715

I also confirmed that the circuit in the 4th gens is about like I said, the one thing I can't figure out is where the sense wire goes to (the electrical diag section has those pages blanked out and sends you to the engine electrical which doesn't have any wiring diagrams)

Tibo

iTrader: (15)

Looks like a decent distribution point but without knowing how thick the metal is that the studs are in I would question how many amps it can carry before it really heats up or sees a voltage drop. Might be worth peace of mind to look up a fourthgen wiring diagram and find out what accessories it was made to power.

83 Crossfire TA

iTrader: (2)

I've owned a 4th gen and have a complete set of service manuals. There are 3 wires coming off the battery plus, an alternator Bat wire (again, no fuse/fusible link), a starter wire, and a wire going to this junction block, and the whole power distribution, both fuse blocks and a mess of other things wire to this junction block.