Alternator upgrade - fusible link question

[MIDNIGHT RIDER]

I found these while nosing around :


http://www.delcity.net/delcity/servlet/catalog?parentid=790086&page=1


and HERE is what I was looking for earlier :



http://www.delcity.net/delcity/servlet/catalog?parentid=790097&page=1


^^^^^^^^^^^^^^^^^^^^^^^^^^

 

[adam g]

Yes 3g's are internally regulated. I did the conversion to my 89 f-250 when I first got it and couldn't be more pleased. I have to jump tractors and other pickups frequently it handles that extremely well. The biggest reason for my choice was that I still live in town and have to make many short trips. This alternator has by batteries charged back up in a few minutes. My old idi were up for that task with their stock 65a and 95 a alternators.

 

[Full Monte]

Mel,

The purpose of all breakers, fusible links, fuses is to protect wires from overloading and burning up or to protect devices attached to that wiring from being overloaded. Any wire that has a #14 connector attached to it will have no more carrying capacity than a #14 wire. Think of it this way: If you have a 1 inch water supply line to your house and you switch down to a 1/2 inch fitting before it gets to the house, you will get about the same amount of water flow as if you had a 1/2 inch water supply line. I may not completely understand your situation, but matching connector and wire sizes is a general design principle that can work well for you.

 

[MIDNIGHT RIDER]

Mel,

The purpose of all breakers, fusible links, fuses is to protect wires from overloading and burning up or to protect devices attached to that wiring from being overloaded. Any wire that has a #14 connector attached to it will have no more carrying capacity than a #14 wire. Think of it this way: If you have a 1 inch water supply line to your house and you switch down to a 1/2 inch fitting before it gets to the house, you will get about the same amount of water flow as if you had a 1/2 inch water supply line. I may not completely understand your situation, but matching connector and wire sizes is a general design principle that can work well for you.

What you are saying is mostly true; but, it doesn't completely work that way.


A 100' 12-gauge extension-cord, with an 8' 16-gauge saw-cord plugged into it, is not going to burn up the saw-motor for lack of current; whereas, on the other hand, plug that same saw into a 100' 16-gauge cord, even though the entire cord is as big as the saw-cord, and pretty soon that motor is going to be smoking.


Make any sense ??

 

[Full Monte]

Yes, it might make sense. The ampacity of wire is determined by the type of wire, the size of the conductor, and the length of the conductor. A longer wire has more resistance than a shorter wire. Without knowing what the current requirements of the saw is, it's hard to know whether it will overheat with the smaller diameter extension cord. What most people don't understand is that electrical accessories, tools, appliances consume POWER, not just current. What happens is that a small supply wire drops the incoming voltage to the appliance. The appliance tries to make up for the decreased power available to it by increasing the amperage draw on the current source, thereby allowing the power to come back up to the required level. Increased current equals increased heat, and increased heat can damage the wiring or the appliance.

To bring this back to Mel's issue, any electrical system is only as good as its weakest link. If that humongous #4wire going to his ammeter has to carry all the starting current and other uses, having a #14 connector on it is going to be a problem. If it carries only a small amount of current for auto accessories, the connector may be OK and the wire size may be overkill for carrying that small amount of current.

 

[Agnem]

Well thanks for the help everyone. I'm done for the moment. Here is what I did. I removed the factory alternator, which I think is in the 70 to 85 range, and replaced it with a new in the box, but at least 5 year old Lestek 135 amp marine rated jobby. It has a slightly smaller pulley than stock, so it should spin a bit faster, which makes me happy. I had to make a 1" spacer for the bottom bolt, since the Lestek casting had a 2" instead of 3" sleeve. Other than that, it bolted right up. I had to cut off my field and stator push button connectors, and replace them with female spade types. I completely removed the factory 10 guage wire, so I could track down the wires to the alternator gauge on the dash. For those of you who don't know, the 80-86 trucks had alt gauges, not volt meters, and they rarely moved at all. That 10gauge wire only needs to go a couple of feet to get the job done, but because of the amp meter being a shunt type, they wind the wire through the wiring harness a total of about 4 feet, so there is enough voltage loss to measure. I then replaced the 10 guage with a 4 gauge that I used crimp on ends with, that I then heat shrinked over. I changed some of the wiring around and made the alternator gauge connections with ring terminals at various points, and adjusted the total length of the wire run, so I now see some needle movement which is an improvement over before. I eliminated the fusable link, and will revisit the idea of a fuse or breaker at some point. I'm using a 10 gauge like the original to power the wire harness at the factory point, but I have more circuits that should be moved over, and I will increase the size when I do that. For now, the alt is capable of feeding the batteries full capacity, and when I hook up the electric fans, I'll feed them from that branch. Pics will come when the fans get done.

 

[MIDNIGHT RIDER]

So this LESTEK is external-regulated ??

 

[Agnem]

Correct. By the factory voltage regulator. I prefer externally regulated alternators, as I find them easier to troubleshoot, and are cheaper to repair / easier to replace when you just have a regulator problem.

 

[MIDNIGHT RIDER]

I prefer externally regulated alternators, as I find them easier to troubleshoot, and are cheaper to repair / easier to replace when you just have a regulator problem.

My sentiments, exactly.

 

[Optikalillushun]

regulator on a 3G is on the back, removed w/ 4 torx bits and cost like $15 at a parts house.

 

[Agnem]

So that should put it right up against the fuel filter. Not knockin' the 3G, but I like this setup better.

 

[u2slow]

I like the circuit breakers by Blue Sea Systems.

One really good reason to keep an over-current device on the alternator lead is to protect in case your battery gets hooked up wrong.

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[Agnem]

Wow! They look like they ought to be about $60 a pop!

 

[u2slow]

Wow! They look like they ought to be about $60 a pop!

Doesn't bother me... its resettable, and cheap insurance. I've seen $1500 engine harnesses and $500 alternators go up in smoke because there wasn't any overcurrent protection.

 

[JPR]

Realizing I am coming late to the party.... I went with a 175 amp fuse and holder similar to this one from Blue Sea which can be had for under $20. (Try Ebay if you can't find the holder locally). Auto Zone had spare fuses in the 100-150 amp range.