Starting and Charging system upgrade

[MT86K5]

I've got a question for all the electrical gurus. I want to replace all my wire and lugs gong from the starter and alternator going to my battery. Would it hurt if I bumped up a gauge like from 4awg to 2awg? I have access to some 2awg welding cable and some good 6awg to replace the smaller stuff. I would think it shouldn't cause any problems but I've been wrong before.

 

[Fordum]

The only possible problems concern connectors and fusible links. As long as you can get the bigger wire to fit a connector that will hook up where its supposed to, thats fine.

BUT, you MUST NOT replace a fusible link with bigger wire.

In theory, if you increase the size of the wire fed by the link, you could increase the size of the link because the bigger wire would handle the increased current.

But, that fuse protects more wires than you are likely to replace, so don't try it.

Otherwise, bigger is better. Isn't it always??

 

[Fordum]

Well, I just thought. Make sure that the wire you use is rated for automotive type use.
It needs to be able to handle the underhood temps, plus water splashing on it and being coated with oil and maybe fuel.

 

[MT86K5]

Thanks Fordum! So the rule of thump is any wire with a fuse I will stick with the same gauge and fuse size. Anything else like the battery ground I can up size no problem.

 

[Fordum]

Thanks Fordum! So the rule of thump is any wire with a fuse I will stick with the same gauge and fuse size. Anything else like the battery ground I can up size no problem.

Nope, you can upsize any wire. Just don't upsize the fuse.

My fault, I thought you knew what I meant about fusible links.

There are certain wires on a Blazer, and most vehicles, that are a little special.
They are smaller in size than the wires feeding them, and have special insulation that is fireproof.
They are called fusible links.

They act as fuses same as the ones in your fusebox. They are designed to melt and burn in two to break the circuit in case of an overload. Since they are smaller in diameter than the wires they feed, they will burn out safely inside the special insulation before the other wires get too hot.

You could upsize the wires going to them and coming from them, just do not upsize the links themselves.

Since I am a Ford guy, and don't work on Blazers everyday like a lot of folks here, I'm not going to say where the links are and what they look like.
I think I know, but its a big difference between thinking and knowing.

Someone else should chime in soon to give you better info.

A lot of people replace them with actual fuses. GM did not use fuses because they cost more, and fuses that handle that much current were not common back then.
Lots of new trucks use fuses now.
Other folks replace them with the same size wire with standard insulation.
Technically this is not correct, but modern insulation is fairly flame retardant anyway, so its not usually a problem.

Personally, the few times I have had to replace one, I bought actual fuse link wire with the special insulation.
But thats just me.

 

[MT86K5]

Ahh, that makes sense. I just assumed that a fusible link was a wire with a fuse inline. I guess that is why it is good to ask questions and not assume you know it all I will keep an eye out for that.

My battery just keeps on dying when I don't start it after a few days or so, so I wanted to just go through the wiring and clean it up hopefully find something that is killing the battery.

I think I'm going to install one of these too, should be pretty handy.

 

[Fordum]

That might work OK, as long as your truck is old enough to not have an adaptive computer that "learns" as you drive.
If it does, its going to idle badly for a while when you first crank it until it relearns the engine.
Also, you will have to reset all your radio settings unless you have one of the old mechanical push button type.

You are on the right track, you need to find out why the battery is going dead. Its either something on the truck drawing current, or a bad battery that has lost capacity or has an internal short.

You need to do a current test to see if there is something drawing current when its not supposed to.

If there is a long time between drives, even the switch is not going to help a lot. Batteries will self-discharge just sitting.

You might consider one of these.

http://www.batteryminders.com/batte...ard-Battery-Charger-Maintainer-D-p-16177.html

Mount a really strong plug on the truck somewhere, and have an extension cord with a cable mounted on it so that when you drive off and forget to unplug it, it will unplug its self without damage.

And you will forget........

 

[randy88k5]

Replacing the stock cables with larger gauge wire is good. Just be sure to route the wires through the same location as the stock cables to keep them away from the exhaust manifolds. IIRC, there is a steel loom around the starter that does just this.

But keep in mind, the electrical draw that is killing your battery might be located somewhere else. The best way to diagnose which circuit the draw is in is to hook up an ammeter in series with the battery. Most multimeters have an amp function. Set to DC amps. Make sure all of the accessories are turned off, especially the headlights. Disconnect the positive battery cable, touch the red lead of the multimeter to the positive battery post, and touch the black lead of the multimeter to the loose positive battery cable. This puts the multimeter in series with the battery. There should be a small number of amps being drawn. 0.1A or a little higher for computer and radio memory draw. It will probably read higher because you have a draw somewhere. Start pulling fuses out of the fuse box (but make sure you keep the door closed for this, as you don't want the dome lights on). Find out which circuits are causing a draw, and how much the draw is for each circuit. Find the one (or more) drawing too many amps when they shouldn't be.

 

[MT86K5]

Replacing the stock cables with larger gauge wire is good. Just be sure to route the wires through the same location as the stock cables to keep them away from the exhaust manifolds. IIRC, there is a steel loom around the starter that does just this.

But keep in mind, the electrical draw that is killing your battery might be located somewhere else. The best way to diagnose which circuit the draw is in is to hook up an ammeter in series with the battery. Most multimeters have an amp function. Set to DC amps. Make sure all of the accessories are turned off, especially the headlights. Disconnect the positive battery cable, touch the red lead of the multimeter to the positive battery post, and touch the black lead of the multimeter to the loose positive battery cable. This puts the multimeter in series with the battery. There should be a small number of amps being drawn. 0.1A or a little higher for computer and radio memory draw. It will probably read higher because you have a draw somewhere. Start pulling fuses out of the fuse box (but make sure you keep the door closed for this, as you don't want the dome lights on). Find out which circuits are causing a draw, and how much the draw is for each circuit. Find the one (or more) drawing too many amps when they shouldn't be.

Excellent Randy, mine does have the amp function and I will have to do that. You explained it better than any write up I found on google.

 

[MT86K5]

Found the problem, pretty simple. First cable I went to replace was the negative for the battery. When I unhooked it from the intake manifold, the copper was extremely corroded so I replaced the cable and its working great now.

 

[Fordum]

That will do it every time!

Glad you found it.

Don't forget that there are two wires on that battery, and they are the same age and have lived under the same conditions.
Be sure to check the positive one.