Upgrade from fusible links to circuit breakers

[FastWoman]

Chuck, the more ordinary variety of fuse is for lower amperages, perhaps up to 30A max (?). The maxi fuses are larger and are for higher amperages. Most importantly, they have more substantial connections capable of handling higher currents. I did finally order a couple of Stinger units. They are indeed a bit "blingish" -- really very pretty, with heavy polycarbonate construction, gold plated contacts, etc. They're more massive than I thought they'd be. Mine, the Stinger SFPD4MAX model, has a base measuring 4 1/4" x 3" and is 1 7/8" high/deep. It completely encoses the fuses. (I hope that's not a problem for heat.) If you wanted something more subdued than the clear polycarbonate housing with the yellow and black "Stinger" logo on the cover, you could always disassemble the unit, spray the plastic parts with black plastic spray paint, and reassemble. I don't think bling is a bad thing, though. ;-)

What wasn't clear from the product info is that this panel is not divided into separate circuits. The left-most connections are ALL interconnected and lead to the battery post. The right-most four connectors are independent. I'll be unbundling a bit of wiring tree to see how to make the conversion. The schematics indicate all the fusible links just lead to the battery, but the wiring harness has separate leads from the battery for each circuit.

I somehow missed the ampacity ratings of the different colors of fusible links, as provided in links given above. (Thanks, guys!) I'm still scratching my head about a couple of things, though:

black is for 80A?! Seems kinda high. I think this line is for the alternator. Shouldn't I drop to 60A, which is the alternator rating?

Brown is not listed in the table on the web page Tomo linked to. It has a lower ampacity than the green, being a smaller cross sectional area (brown being 0.3mm^2, and green being 0.5mm^2). There seems to be some use of red ratings in place of brown, perhaps because of color confusion. However, this would be incorrect. I've seen references to the brown being 30A, which is the same as pink, but obviously not colored the same. Has anyone figured out the brown?

Thanks!

Edited August 29, 2009 by FastWoman

[ConchZ]

I've been through the same thing with the fusible link on a 1973, which originally had a 40amp alternator, with a black fusible link. While maybe the link is good for 80amps if its a certain length, I bet it wasn't sized to stand up to 80 amps in a 73 with a 40amp alternator. There's just no reason it should be rated higher than the alternator. Anyway, I replaced it with a 40amp maxi fuse. I tried a 30amp, but that would blow when the alternator was putting out its max output. Its been a while, and nothing has fried or caught fire, and the fuse doesn't blow, so I think its good.

[Zs-ondabrain]

Same thing here, got tired of all the wires all over the place. I'll have to deal with this same thing on the 260Z. My caps are in good condition but ya'll know me, *UPGRADE* time.

Dave

[TomoHawk]

One more upgrade option you might want to look into:

http://www.zcarcreations.com/howto/maxifuse.htm

[sblake01]

The disclaimer would concern me in considering that one:

WARNINGS

THIS CONVERSION IS FOR OFF-ROAD USE ONLY. These instructions are listed for informational purposes only and as performed on a 1977 Datsun 280Z originally equipped with an external voltage regulator. Conversions on ALL other model years will vary and any conversion attempted is not the responsibility of Z Car Creations.

Your Z car's electrical system handles high amperage direct current. Improper installation or use can cause injury, including fire, burns, and electric shock. For use only in specified vehicles.

The components listed in this conversion have been designed to handle a maximum current rating of 110 amps, 12VDC. Do not exceed.

This conversion is designed for an already functioning system. Batteries and battery cables must be in good condition. Do not attempt this conversion if your electrical system does not function, your battery is discharged, or there are shorts in your system or any of its components

[TomoHawk]

Of course. Any modification, or even a repair, should be carefully investigated, planned, and executed; especially on an old car like a Z. You wouldn't want the car to quit while driving on a crowded highway...

[sblake01]

Of course. Any modification, or even a repair, should be carefully investigated, planned, and executed; especially on an old car like a Z. You wouldn't want the car to quit while driving on a crowded highway...

My car never quit at any time in the 12 years that I owned it. Without any kind of fuse upgrade. They were in good condition when I got the car which, unfortunately, isn't always the case. I did the vinegar bath thing on them, replaced the links and plastic covers, both of which you could easily find 12 years ago, today, not so much, and never had a problem with them throughout the rest of my ownership. However primitive the fusible link setup may look, Nissan actually did a pretty good job on them. It's lack of maintainence, previous owner modification/abuse, etc. that kills them. Back to the Z Creations upgrade. I know they're just covering their butts with those warnings but the 'off road' statement would steer me away from wanting to use their conversion. Edited August 30, 2009 by sblake01

[TomoHawk]

That applies to any car, not just a vintage Z. I see reports of 'disabled' vehicles on the freeway every morning. Some people just don't put enough attention into maintaining their cars.

If something isn't supposed to be reliable or safe enough for street use, why would you want to put it on a vehicle use off-road? The Baja race trucks come to mind...

Edited August 30, 2009 by TomoHawk

[sblake01]

Fair enough, as I can see that this will go nowhere, as usual. We're agruing different points. Or, at least, you're agruing, I'm just stating my point of view from my experience. Let it go, okay, as I'm done with it.

Edited August 30, 2009 by sblake01

[FastWoman]

Er... Sorry to have rekindled an old argument.

Personally I'd have no issue with keeping the fusible links, if it were not for the fact that they are crumbly, and one of my assemblies is literally hanging on the ends of the wires, due to the broken base. My contacts are corroded, a couple of the fusible links have gotten toasty enough to scorch and crack the rubber insulation, and one of my connectors fell apart (although I put it back together). All in all, I don't know whether I can depend on what's there to keep me running. I'm reminded of when I learned what a fusible link is. It was when my '75 model died in the middle of a highway U-turn and I had to have it towed. I had bought the car at 8 years of age (the car's, of course) and replaced the crumbled cover at that time. The fusible link deteriorated a couple of years later -- about age 10. Now my '78 is 30 years of age and in somewhat more frail condition than my '75 was when it was a mere decade old. I just don't trust those dangly, crumbly things. So as much as I hate to go non-stock, the mod will be happening -- probably over the next couple of days.

Regarding the other mods, there's no need to upgrade to an internal regulator system, as I already have that. However, I'm thinking about wiring my headlights to relays to offload current from the combo switch. When I switched on my lights the other night, they didn't immediately come on. It took a jiggle or bump (?) before they spontaneously lit up. Other than that I've not had problems. Anyway I have 6 fusible links, to be housed in 2 4-fuse blocks. The 7th position will go to a 30A fuse to the stereo (currently in an inline fuse holder), and the 8th position could supply the headlight relay.

So can anyone confirm the amperage value of a brown fusible link? 30A?

Edited August 30, 2009 by FastWoman

[sblake01]

Er... Sorry to have rekindled an old argument.

No need for you to apologize. Those types of exchanges between myself and my esteemed colleague go way back. As far as the brown fusible link goes, I don't ever recall using on an a car or truck but I have a Cooper/Bussmann chart that lists them at 70A.

Edited August 30, 2009 by sblake01

[FastWoman]

Thanks, but something is amiss. The Nissan brown links must depart from normal color code standards. The brown is lighter gauge than the green, at least on my '78Z.

I think I'm going with 30A. If you compute ratios between the black and green, the green is 125% of the ampacity of the black, when adjusted down for cross sectional area. If you apply the same 125% when adjusting down to the brown from the green (i.e. taking the ratios of their x-sec areas, times green amps, times 1.25), then you get 30A.

I finally looked at the schematic for my headlights. It seems one of the fusible links is already devoted to that, so I guess I'll still have a spare fuse position. My current plan is to wire the headlight socket output to two relay coils -- one for high beam, and one for low. I'll then run a wire in parallel off of the headlight maxifuse to the respective relays, with the output running in parallel to the high and low beam filaments, with the center connector grounded on each. Thoughts, anyone?

Finally, I'm guessing this is the lineup of the fusible links in my '78. I think I would know so much more about what I'm doing if the schematic foldout hadn't been ripped out of the FSM that I bought:

All color codes -- W towards battery, W/R towards circuit

1. Headlight (brown?) -- runs to combo switch, and then to headlight bus of fuse block.

2. Battery (brown?) -- runs to bat bus of fuse block.

3. Battery (brown?) -- runs to the ignition switch.

4. Ignition (brown?) -- runs to ignition relay and then ignition bus of fuse block

5. Accessory (brown?) -- runs to accessory bus of fuse block

6. Alternator (black) -- runs from output of alternator to + of battery

7. EFI (green) -- runs to EFI main relay and then to drop resistors for injectors

8. EFI (green) -- runs to EFI main relay and then to EFI control unit

So that's 8 circuits total, and there are 6 fusible links. That would mean that two of the circuits from 1 through 5 are really part of other circuits and are simply diagrammed redundantly on in the various pages of the FSM. If I had the fold-out schematic, I'd know which ones. I guess I can trace it all out, but can anyone help me with this one of the top of his/her head?

Also are my fusible link color codes correct for the circuits described? (Nissan wasn't kind enough to provide any useful info in this regard in their FSM.)

Thanks!

Sarah