Just installed a new 1 wire alternator and need to install a fuse… what size fuse?? (2 Viewers)

[Landlover12]

Thanks everyone.

I have a two wire alternator wired direct to the battery.

My goal is to fuse the wire that goes from the alternator to the battery if that’s the right thing to do.

I installed my own amp meter so I guess o can disconnect the one on the dash. Should I just cut or disconnect the wire behind the dash?

 

[ToyotaMatt]

Just installed a new 1 wire alternator and need to install a fuse… what size fuse??

Anyone have experience with this style fuse? I like the clean simple look but I want to make sure it’s the right style for the set up.

https://a.co/d/hBnMY5H

Currently running one battery on the FJ. It has a winch that I’m going to hook up. Used to have a two battery set up. Can I run the winch off one battery or do I need a second?

View attachment 3802860

View attachment 3802862

Hi

how come you went with a non-oem / Non-Genuine NipponDenso alternator platform of any kind ?


matt

 

[pb4ugo]

Usually with the alt connected to the batt the stk ammeter won't work. You can disconnect the stk ammeter, but you'll have to connect the 2 wires it uses together to complete the circuit. Of course we really don't know how you hooked everything up.

 

[Grayscale]

Thanks everyone.

I have a two wire alternator wired direct to the battery.

My goal is to fuse the wire that goes from the alternator to the battery if that’s the right thing to do.

I installed my own amp meter so I guess o can disconnect the one on the dash. Should I just cut or disconnect the wire behind the dash?

If you cut or disconnect the factory amp meter than there is no path, in the factory harness, of current to the fuse block. Don't you mean volt meter? The White and White/Blue wire at the back of the factory ammeter need splicing together if you are to bypass the factory ammeter if current now has to flow from the battery-positive to the fuse block.

The charge-circuit in the stock harness wasn't fused, it was protected only at the battery by a fusible link. With the higher output alternator, the stock harness and fusible link are under-sized. So the reconfigured charging bypasses the branched circuit, and now all the vehicles load (aside from the starter and winch) goes thru the circuit with the factory fusible link, instead of just the battery discharge and recharge. Maybe the alternator gets hooked up to the factory harness White/Lavender (to energize the fuse block), and you introduce a low-resistance direct path with large-gauge cables from the battery to the alternator for high-output charging?

 

[Landlover12]

Thank you for the above.

Yes I meant to say I installed a volt meter.

Below are two photos showing how my alternator is connected to the battery.

I’m trying to figure out if I should fuse that red wire that comes from the alternator to the battery.

Is there any negatives or risk for me just keeping the factory amp meter on the dash connected?

 

[Landlover12]

What circuit are you trying to protect?

Is you plan is to wire the new alternator directly to the battery? And let the old harness stay attached the the alternator - as normal?

What you don’t want to use is pull 91 or 100 thru a 50 year old design that maxes each fuses to around 20 amps.

Also, you need to consider bypassing your amp meter in your dash board or shunting it to not have a flash or a fire in your dashboard.

Old harness is disconnected

 

[Grayscale]

The alternator output is over-sized for the existing harness. From the photo, it barely fits the alternator bracket and position of the battery.

I'm feeling that at 12V, any kind of short that is just rubbing wires, isn't going to draw enough current to blow a 100-amp fuse, as the short has tons of resistance (oxidizing metal, and melted plastic). In other words, the truck will burn long before the fuse will blow. Maybe that is why there is no fused circuit between the battery and the starter? I don't really know.

The factory wiring configuration protected the amount of current flowing to and from the battery with the fusible link. Is there currently a fusible link connected to the positive-terminal?

 

[DeskJock]

IIRC there are many threads on this topic that walk thru the pros and cons of NOT using a factory alternator.

Personally after reading thru them - I choose to stay with something close to factory via @ToyotaMatt. We choose a 65 amp alternator that we believe is a the max we were comfortable with and continuing to use the max fuses that the fuse box was designed for

With that said. There are many folks running your setup. Is that setup as as safe as factory - I personally don’t think so.

 

[ToyotaMatt]

Just installed a new 1 wire alternator and need to install a fuse… what size fuse??

Anyone have experience with this style fuse? I like the clean simple look but I want to make sure it’s the right style for the set up.

https://a.co/d/hBnMY5H

Currently running one battery on the FJ. It has a winch that I’m going to hook up. Used to have a two battery set up. Can I run the winch off one battery or do I need a second?

View attachment 3802860

View attachment 3802862

if i missed it ? what is the AMPS Rating Spec. output of your new aftermarket Alternator your trying to hook up ?



this is actually super important to know right now as mr @DeskJock first mentions above .............like super critical in-fact ....!

.


you have a large gauge white wire and a large Gauge white wire w/ blue tracer stripe , depending on your modle year it can be various Gauge or thickness ?

you exceed it's amp rating and BAD BAD things can and will occur ......

FACT:

 

[Landlover12]

No fusable liks

if i missed it ? what is the AMPS Rating Spec. output of your new aftermarket Alternator your trying to hook up ?



this is actually super important to know right now as mr @DeskJock first mentions above .............like super critical in-fact ....!

.


you have a large gauge white wire and a large Gauge white wire w/ blue tracer stripe , depending on your modle year it can be various Gauge or thickness ?

you exceed it's amp rating and BAD BAD things can and will occur ......

FACT:

 

[Grayscale]

you have a large gauge white wire and a large Gauge white wire w/ blue tracer stripe , depending on your modle year it can be various Gauge or thickness ?

you exceed it's amp rating and BAD BAD things can and will occur ......

FACT:

But, aside from the ignition circuit, and everything after the ignition switch is governed by the factory fuse block. So, the draw of amps thru the factory harness isn't going up. And, the jumbo battery cables are probably enough to cover battery-charging.

Maybe there was a reason why the alternator didn't go straight to the battery? The original Land Cruiser F/2F alternator runs straight to the ignition switch and fuse block with a fusible-link-protected branch for battery charge/discharge. I'd like to see a GM wiring diagram.

 

[Landlover12]

But, aside from the ignition circuit, and everything after the ignition switch is governed by the factory fuse block. So, the draw of amps thru the factory harness isn't going up. And, the jumbo battery cables are probably enough to cover battery-charging.

Maybe there was a reason why the alternator didn't go straight to the battery? The original Land Cruiser F/2F alternator runs straight to the ignition switch and fuse block with a fusible-link-protected branch for battery charge/discharge. I'd like to see a GM wiring diagram.

I’m not using the original alternator wireing harness like you mention.

Do you think I should fuse the wire coming from the alternator to the bat?

 

[Grayscale]

I’m not using the original alternator wireing harness like you mention.

Do you think I should fuse the wire coming from the alternator to the bat?

Are you using the original ignition switch? Is there a fusible link on the battery-positive with this harness?

If you install a fuse between the alternator and the battery, it might be a unique kind of installation. Did GM make such a configuration? If it blows, the battery will continue to run the ignition so the motor will keep running. Without a voltage signal from the battery, will the alternator stop charging, or will it keep charging until it burns-up or burns-out?

 

[bhsdriller]

Yes always fuse the alternator to battery connection in that type of configuration. Size the fuse according to wire size used
There's charts online that will tell you

 

[DeskJock]

Are you using the original ignition switch? Is there a fusible link on the battery-positive with this harness?

If you install a fuse between the alternator and the battery, it might be a unique kind of installation. Did GM make such a configuration? If it blows, the battery will continue to run the ignition so the motor will keep running. Without a voltage signal from the battery, will the alternator stop charging, or will it keep charging until it burns-up or burns-out?

I’d study a fuse vs and circuit breaker. And study what amperage would be needed for your application. You have two issues to wrestle with 1 Load and 2 a short.

You will need to either find a fuse that can handle the load, or a circuit breaker that will work properly with the load and a short.

The 20 amp fuses in our rigs - aren’t really intended to handle 20 amps thru the harness on a particular circuit. It’s likely that the circuit is intending to see 10 to 14 amps typically - so the 20 amp fuses covers the expected load, and promptly deals with a short.

I had a Chevy Tahoe many years ago - it had a fusable cable from the alternator to the battery ( don’t ask me how I know).

Good luck.

 

[pb4ugo]

Imo, Ammeter charging systems are old and antiquated. Running the charge wire from the alt to the batt is similar to GM. GM uses a junction block for the connections instead of the batt. You could add a fusible link on the charge wire. You can search the internet. I found you need to use fusible link wire 4 gauges smaller. I ran a 6 gauge alt to batt with a 10 gauge fusible link at the batt. You can leave the ammeter hooked up, I bypassed it by connecting the white and white/,blue ammeter wires together from the back of the ammeter. I would attach your charge wire to the larger post with the starter. I used the batt clamp bolt. I hooked my winch to that stud once, the stud got hot and melted the lead holding it in place. I connected the white wire with a fusible link to the positive batt stud. The white wire powers the fuse box. There's good tutorials on mad electric's site.

 

[Grayscale]

Using the lug on the starter, as a kind of busbar, will be safer in my opinion. (As pb4ugo described above.)

The battery itself should be away from any conventional fuses, it can be near 'fusible link' because fusible link melts before it combusts, supposedly. The cells in the battery are only so good at charging or discharging, so you want to keep sparking fuses away from any out-gas from the battery's electrolyte, as it can explode.

In a slower sense, the corrosion is notorious just on top of the battery cell, try to keep the connections here as simple/serviceable as possible, locate regular fuses on one side of the circuit, and use fusible links on the battery side.

 

[Grayscale]

How much resistance will the Amazon-fuse create on the charging circuit between the battery and alternator? What is that voltage drop with the higher Amp output alternator?

The GM repair manual tells you to check the fusible link between the battery and alternator if charging problems present themselves, but, apparently there is no conventional fuse between the alternator and battery.

When I was driving my dad's former '92 LeSabre this summer, the battery positive cable shorted and caught fire. I extinguished the burning cable and somehow managed to get the hot, shorting cable away from ground, with bare hands. The fire department arrived and disconnected the battery leads. The problem was related to corrosion on the positive terminal, and the bad installation of a non-factory battery lug and absence of factory cable clamps between the battery and the starter.

 

[charliemeyer007]

There is reason I carry a small fire extinguisher and have a small box end wrench tied up by the battery.

 

[Grayscale]

There is reason I carry a small fire extinguisher and have a small box end wrench tied up by the battery.

I wish I had water. I still have an engine bay with fire extinguisher powder in it; I'm not sure how to clean it up. Carrying (unfrozen) drinking water is essential for serious travel, and it would have been better to have it on this little fire.