3G Alternator Fuse

bit · Jul 13, 2006

What fuse are you guys running for you 3Gs? I have seen articles saying to run everything from 135 to 175. I am running a 150AMP fuse in mine now. I have only tested it at idle and everything seems to be fine. I came across this chart today showing the 3G capable producing nearly 175 Amps at 4000RPMS, that is about 2000 engine RPMs.

I know if I turn everything on I do not have 150 amps worth of accessories, but have you guys had problems with amperage spikes blowing fuses?

Thanks
Brent

rockyracoon · Jul 13, 2006

im running a 150a wafer fuse,which is the amperage that I believe a lot of other people around here are using.you shouldnt ever blow the 150 unless there is a short.

Jaswir · Jul 13, 2006

using a 150amp wafer fuse to

HISSIN50 · Jul 13, 2006

It can be useful to remember that the fuses used are often 'slow burning'. That is, they can take a current spike before blowing (the amount needed to make it blow depends upon the amount of current and the time interval of the spike).

srothfuss · Jul 13, 2006

150 for me also... I drive a minimum of 2 hours on the back roads every weekend (straight torture for the tires) but the fuse has never blown.

795.0pacecar · Jul 13, 2006

Im runnin a 200amp fuse. I bought a 3g conversion kit and thats what it came with.

90blacknight · Jul 13, 2006

I was speaking with an electrician who's owned fox bodied mustangs before and use to run 130 amp alternators and he said he had never heard of using a fuse between the alternator and the battery. He told me it serves no purpose and just limits power to the battery. I just recently installed and 3g alternator and was shopping around for a fuse when I ran into him. So I'm not sure what to do. He told me that the fuse would not protect the alternator from blowing a diode and therefore was pointless alltogether. Can someone confirm this? He also advised against using audio 4 gauge as the preferred cable as it is not heat resistant and would limit power. Many people here are using that cable and not battery cable and I must admit I can't understand why.

blackcloud50 · Jul 13, 2006

90blacknight said:
I was speaking with an electrician who's owned fox bodied mustangs before and use to run 130 amp alternators and he said he had never heard of using a fuse between the alternator and the battery. He told me it serves no purpose and just limits power to the battery. I just recently installed and 3g alternator and was shopping around for a fuse when I ran into him. So I'm not sure what to do. He told me that the fuse would not protect the alternator from blowing a diode and therefore was pointless alltogether. Can someone confirm this? He also advised against using audio 4 gauge as the preferred cable as it is not heat resistant and would limit power. Many people here are using that cable and not battery cable and I must admit I can't understand why.

With a factory alternator, the black w/orange stripe power wire has a fusible link in it near the starter solenoid. Ask them why Ford did that and then tell me if there should be a fuse inline or not

795.0pacecar · Jul 13, 2006

If something were to ground out I would like that fuse to be there to keep 200+ amps from setting my car on fire.

blackcloud50 · Jul 13, 2006

heat will affect (lower) the current rating of both fuses and wiring ampacity. But you still will get enough current rating in a good quality 4awg to handle the load for you alternator. Or just step up to 2awg

bit · Jul 13, 2006

90blacknight said:
I was speaking with an electrician who's owned fox bodied mustangs before and use to run 130 amp alternators and he said he had never heard of using a fuse between the alternator and the battery. He told me it serves no purpose and just limits power to the battery. I just recently installed and 3g alternator and was shopping around for a fuse when I ran into him. So I'm not sure what to do. He told me that the fuse would not protect the alternator from blowing a diode and therefore was pointless alltogether. Can someone confirm this? He also advised against using audio 4 gauge as the preferred cable as it is not heat resistant and would limit power. Many people here are using that cable and not battery cable and I must admit I can't understand why.

The fuse serves a valuable purpose. If the regulator goes bad and the alternator puts out max amps it will burn up the cable and start a fire, as well as boil the battery and damage accessories. As for the cable, I am using 4 gauge starter wire designed to withstand the under hood temperatures, however, the audio wire some are using should be fine as it is also designed to run under the hood for direct battery connection.

Brent

HISSIN50 · Jul 13, 2006

I agree about the reasons for the circuit protection - it's needed.

I see the guy's theoretical point about not using oxygen-free connections, etc, but it's really kinda moot for something crude like this.

I replaced the OEM cable on my '94 (6 AWG cable) as it was dropping 400 mA. The new 4 AWG cable drops an avg of 4 mA. The former is an oem connection and the latter is a cable I made (with an ANL fuse). I'd take the latter.

speedytang · Jul 14, 2006

I run 100amp fuse since everything on only pulls 78 amps I didn't want a fuse to large or it would take a few seconds to pop which might be to late.

3G Alternator Fuse

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