Alt conversion fuse

Hi, I'm in the process of converting to a 100 amp cs130 alt. I plan on putting a Maxifuse block between the alt and battery, but I'm not sure what amp fuse to use. Little help?? Thanks

 

The factory uses a fusible link, IIRC.

To pick a fuse, you'd typically choose a fuse that is rated at the maximum current you anticipate, plus some headroom. So a 150A fuse might be appropriate.

I'd use a fusible link http://madelectrical.com/catalog/fusible-link.shtml - what's the size of the wire from the alternator to the battery? The ampacity charts show a #3 or #4 wire to safely carry 100 amps... this seems pretty large, ie battery cable sized.

What cars use this sized alternator? I'd take a look at their wiring diagrams to determine what sized wire to use.

 

I used #4. What gauge fusable link should I use?

 

Well, I don't know of a source for larger than what MadElectrical has. They suggest a 12 ga link for #8 or larger.

You could send them an email or call.

 

You know. A 1995 S-10 positive battery cable has a wire the goes from the battery to the alternator. You could buy one. It has the fusible link already in it. I'm looking at mine right now.

 

The question is, how much draw is your rig using on a continuous basis. That CS130 won't put out a continuous 100amp for very long. The fusible link as Tim sez won't be needed any bigger than a 12 ga. The fusible link is to protect the alternator from a direct short on it's output or a sustained very heavy draw. If you are drawing more than 80 amp continuous then you need to go to a commercial grade alternator or consider running two alternators.

 

Where should the link go? Directly on the alt, in the middle of the 4awg cable, or on the battery?

 

Usually the alternator connects to a post on the starter solenoid. The fusible link would go between the alternator and that post.

Do you have an ammeter? If so get rid of it unless you want a dash fire.

It would also help toput the year and model of your Jeep in your signature file.

 

I've got a 74 cj5 304. No ammeter, changed to voltmeter. Can I go straight fron the alt to the selenoid with JUST fusible link wire? Or should I put it in the middle of 4 ga. cable, or at either end of the 4ga? Thanks for the help.

 

Just use the full fusible link wire from the alt to solenoid if it is long enough.

 

It's not a good idea to put a fuse between the alternator and the battery. They're usually connected by a un-fused wire BUT you should have a fuse between those two and the rest of the electrical system. Actually they usually run a short fusible link from there to the fuse block and it then connect to a bunch of smaller (15, 20, 30 Amp) fuses that in turn connect to the various electrical sub-systems. The reason that you don't generally use a fuse between the battery and alternator is because if it opens then your alternator will run wide open with no regulation and will usually burn itself up. Most electrical devices (not just automobiles) are designed so that the battery provides a load for the charging system and it needs to be connected for the charging system to regulate the voltage output properly. Without the battery, many charging systems will provide to much voltage and burn out themselves and anything connected to them. However if you decide to put a fuse (or fusible link) between them then it should be rated near the maximum sustainable (not peak) output of the alternator.

 

Re: fusible links.

Fusible links aren't intended to operate as fuses. Fuses are used to protect individual devices from overloads. Therefore, there will be at least one fuse for each device to be protected and each fuse will be rated slightly higher than the normal amount of current that that device will draw.

Fusible links are intended to protect the wiring harness itself. As such they're usually used in circuits that feed many devices so the current varies widely depending on what is turned on (wipers, headlights, fuel pumps, auxillery lights, etc). Think of a fusible link as being a normal part of the harness except that in the event of a SEVERE overload it will burn out before the rest of the harness! Normal practice is to calculate the maximum load in the circuit and then select the appropriate gauge wire to handle it and then use a short length (~4 to 6") of wire that is two sizes smaller as the fusible link. The smaller size will insure that it burns out before the wiring in the harness.