Mega Fuse?
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Fleet Mechanic
Joined: Feb 2009
Posts: 1,672
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From: Nixa
Mega Fuse?
I'm finally getting ready to do the 130 amp 3g alternator upgrade. After doing extensive reading up on the swap, I haven't found any info on what amp mega fuse I need to get.
I will eventually have a 12,000 lb. Ramsey winch on my truck, if that info is needed.
Thanks in advance.
I will eventually have a 12,000 lb. Ramsey winch on my truck, if that info is needed.
Thanks in advance.
Laughing Gas
Joined: Oct 2014
Posts: 1,227
Likes: 4
From: Washington
When did they start using the 3g at the factory? My '95 came with the 95 amp 3g, and I just swapped it out for a 130 amp with no changes to the wiring. I figured all '92-'97 OBS trucks came with the 3g.
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
Ford phased them around 1993 (same time they had to release the TSB on failing 2G harnesses catching fire)
If you go from 95 -> 130A output you really ought to increase the charge cable size (decreased wire gauge)
If you go from 95 -> 130A output you really ought to increase the charge cable size (decreased wire gauge)
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 40
From: EXTREME southwest CT
Plenty of documentation showing these alternators put out 160+ peak amps.
If he runs that winch it will blow a 150A fuse every time.
Laughing Gas
Joined: Oct 2014
Posts: 1,227
Likes: 4
From: Washington
Only if you also increase the load. The alternator will only put out what is needed by the system. Since the rest of my system is stock, I don't need to make any other changes. If I were to add a winch or large stereo system, then I would need to upgrade the charge wire.
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pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
What pushed you to "upgrade" to a 130A alternator?
What do you think is going to happen to that 8Ga. wire when you accidently kill the battery and the new alternator charges at 160+ amps?
What do you think is going to happen to that 8Ga. wire when you accidently kill the battery and the new alternator charges at 160+ amps?
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And I assumed since we're talking aftermarket fuses, that the charge wire has already been appropriately upgraded.. I'd run 4GA @ 150A personally.
For first hand knowledge, I run 150A fuses on my 130A alts, have enough drain to pull voltage down to under 12V, and have never blown that fuse. I've done this on multiple vehicles.
As an aside, do not try to fuse the oe wire at 175A. You short that wire out and you're risking a fire. That's what the fuse is really there for, protecting the wire, not the alt. Put it as close to the battery as you can.
Cargo Master
Joined: May 2001
Posts: 3,208
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I have used the charge wire from the Taurus that the 130 amp came from. It is either a #4 or #2 wire with 2 12ga fusible links with eyelets spliced on the end that attaches to the solenoid. I have bought those fusible links and made other charge wires. I have also spliced in the inline mega fuses. But definitely upgrade the charge wire and add some protection.
Laughing Gas
Joined: Oct 2014
Posts: 1,227
Likes: 4
From: Washington
This wasn't an upgrade. I am familiar with the alternator, because I installed it on my '69 F250 with a 4 gauge charge wire, and 175 amp mega fuse. Also, if I choose to add components to the electrical system the capacity for them is already there; at a nominal cost over the stock alt.
I'm not worried about the 8 gauge charge wire at all. It's the same wire used on vehicles that come with the 130 amp alt stock. Plus if the battery's dead I'll have it on a charger, because it won't start anyways.
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Fleet Mechanic
Joined: Feb 2009
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From: Nixa
Thank You all for all your input so far. I appreciate it. I'll take all I can get.
My truck has always had a problem of voltage dropping from say 14 volts down to say 8 (I'm just guessing at those numbers) when coming to a stop. It don't matter if I have anything turned or not, but it definetly gets worst in the winter with eater, lights etc. on.
Lately if I'm just idling along in a parking lot or in traffic, my truck almost wants to die because not enough power is keeping the engine running, I'm almost 2 footing it to keep rpms up to keep the alternator charging.
I heard about this upgrade after I had already bought a stock replacement alternator about 1 1/2 years ago. I was told and have read that this upgrade will fix my problem.
I wish I could find the stock battery cable set up, but all I have found is that it is no longer available. All I can hope to do is find one in good condition at the pick n pull.
My truck has always had a problem of voltage dropping from say 14 volts down to say 8 (I'm just guessing at those numbers) when coming to a stop. It don't matter if I have anything turned or not, but it definetly gets worst in the winter with eater, lights etc. on.
Lately if I'm just idling along in a parking lot or in traffic, my truck almost wants to die because not enough power is keeping the engine running, I'm almost 2 footing it to keep rpms up to keep the alternator charging.
I heard about this upgrade after I had already bought a stock replacement alternator about 1 1/2 years ago. I was told and have read that this upgrade will fix my problem.
I wish I could find the stock battery cable set up, but all I have found is that it is no longer available. All I can hope to do is find one in good condition at the pick n pull.
Senior User
Joined: Aug 2006
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You don't have an alt problem, you seem to have a wire problem. If it was just the alt, your voltage would drop to battery voltage for short periods, which isn't enough to cause problems running. You can drive for a half hour or longer on just a battery. (depending on other loads and your battery capacity of course). If it's dropping well below battery voltage, you have either a strong short, or wiring veery poorly connected or falling apart.
As far as the battery cables, just make your own. The oem cables are generally a bit undersized anyways.
As far as the battery cables, just make your own. The oem cables are generally a bit undersized anyways.
