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2003 Forester XS Auto
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Discussion Starter · #1 ·
Thanks for taking a look!
First, let it be known that while I very much enjoy DIY projects, electricity has always seemed more like magic to me. Resistance, wattage, ohms, etc are like words from some long-lost enchanted place. Anyways...

I've been having an issue with the positive terminal on my alternator for over a year now. The first time it happened I thought it was a battery issue, but discovered that the positive terminal on the alternator had fused/melted over time. I ended up pulling a used post/bracket from a junk yard and mounted that without changing out the alternator. I also spliced the wires (turns out there's 2) where they had been corroded/burned/melted and made new connections. I used crimp connectors for the wires and stacked the two wires' end connections on the post and it worked just fine... for about 6 months. When I started experiencing similar issues, I found that it was happening again. I managed to again find another post and performed the same procedure again, which has lasted for another 6 months, during which time I replaced my alternator. Now I'm finding that the wrapping around my crimp-jobs is melting and the wires are getting hot at the crimps. (Also, I have also always noticed that my headlight dim just a little whenever I stop and go... is that weird?) I called Subaru parts and they told me that the wire that I've been having issues with is part of a $400 harness that powers everything in the front of the car.

So my question for those who have more experience in car electronics than me is: what is causing this, and how can I fix it more permanently? I recently bought a soldering iron and solder to fix a wire that my cat chewed through, and I am perhaps the world's worst solder-er. But I will try soldering new wire connections in my car soon. Besides that, what can I do?

Thanks again for looking!
 

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2007 Forester Sports XT 4EAT
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First, we haven't had an issue like this in my son's '03 X. :confused:

If it's getting hot at the crimp(s) you made, it's either a poor connection or a high resistance connection. The easy fix is to solder those connectors, which should improve the electrical connection. If those are insulated crimps, you'll have to remove the crimp insualtion before soldering. As a rule, I always crimp & solder my power connections. That way there's no chance of getting a poor connection.

As to Subaru using 2 wires from the alternator to the fuse box. I'm going to guess that's done to reduce the size of the wire... 2 small ones = one large one + much more flexible than one big honking cable. :wink:

Bobby...
 

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internal connections in the alternator could be suspect if changing the stud eventually repeats the problem, but you say you have changed alternators now, so....

If the cable connection isn't tight or clean enough, can cause excess resistance, when combined with high current equals extreme heat generated.

Less looked at option, bad engine or alternator grounds.

If you don't know how to solder properly I wouldn't bother trying to add solder to the connections you made, if properly crimped it should be sufficient.

How are the battery connections?

How is the battery?
 

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2003 Forester XS Auto
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Discussion Starter · #4 ·
Battery connections are very clean, and battery has been recently tested as good... I guess I'll clean and reconnect all of the grounds I can find, and do my best to solder some new connections this weekend. Thanks for the insight!
 

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03 Forester 2.5X 4 Speed Auto
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674 Posts
I'm not going to sugar coat it. Sounds like your connection sucks. Bad connection = resistance = heat = possible fire

I know a thing or two about soldering. And I have a 16 ton hydraulic crimper. If you want to send me a chunk of cable and the connectors you want to use, I'll hook them up for you and send it back.
 

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You are talking about the charging wire coming off the alternator? DO NOT solder those with a soldering iron. Use a blowtorch, flux, and solid core solder.

A soldering iron won't have enough heat. No where close
 

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03 Forester 2.5X 4 Speed Auto
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And just FYI here is what my crimp connections look like if I cut them open. One solid, cold-welded piece of copper. Keep in mind that you have to use copper terminals though. The silver/gold plated brass terminals don't cold weld with copper too well.


► Edit - moderator's note - the image on this post is not recoverable. :frown:

Bobby...
 

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2007 Forester Sports XT 4EAT
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You are talking about the charging wire coming off the alternator? DO NOT solder those with a soldering iron. Use a blowtorch, flux, and solid core solder.

A soldering iron won't have enough heat. No where close
Not entirely true. You just have to use the correct wattage soldering iron. I can easily solder up to 8 gauge with a 40 watt soldering iron & 60/40 (tin/lead) resin core solder. When I did a 6 gauge cable for the '95 Neon this summer, part of relocating the battery to the trunk, I switched to a 110 watt soldering iron. For the 2 gauge cables to the rear located battery, I did use a torch. I used CL-flux on the cable strands & a solder pellet in the terminal. Once cooled, the insualtion is pushed back to the terminal & shrink tubing is applied. I used marine grade cable & terminals (tinned). :smile:

Bobby...
My DIY torch soldering jig. The washers holding the lug are stainless steel, so the solder doesn't stick to it.

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Good point on the smaller wire, bobby. I guess I needed to switch my brain off from the 0 gauge and up that I use haha.

Good choice on the terminals. I use the same! Have you cut any of the connections open to see how much solder penetration you get?

I'm not sure if you have seen it, but you can purchase these cool solder pellets designed for soldering this type of terminal
Solder Pellet Solder Slug for 1 0 AWG Wire Black 2pack | eBay

But that being said, I prefer crimping :)
 

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2007 Forester Sports XT 4EAT
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No, but with the CL-flux placed on the wire strands, you can see the solder wicking up into it as the lug. The solder pellet method works well on larger lugs. It's a little spooky watching that molten solder as the cable strands are slowly pushed into the soup! :icon_eek:

We had to solder on 6 lugs on the #2 cable we ran in the '95 Neon (engine compartment to the trunk) & it's not something I want to do again! I don't mind sodering with an iron, but working with a torch is tricky, as there's so much heat to control!

I bought a crimper, but decided to solder. Solder does more than make the electrical connection, it helps seal & protect the wire strands from water wicking up & under the insualtion. Even applying shrink tubing can't prevent water wicking 100% of the time. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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I bought a crimper, but decided to solder. Solder does more than make the electrical connection, it helps seal & protect the wire strands from water wicking up & under the insualtion. Even applying shrink tubing can't prevent water wicking 100% of the time. :wink:
When it's done properly, it seems that the connection is almost never the weak point. So I think the difference in the end result of solder vs crimp is nil. Although I do like the marine grade 'crimp' connectors that you use. They are much thicker and more solid than the dinky brass terminals I see lots of people using. I only chose to crimp because I did NOT want to solder 20 plus 0 gauge terminals hahaha




I think it is worth noting, for OP, that this type of terminal can only be soldered. My tests have shown that they don't take very well to crimping :biggrin:

I'm not sure what type of heat shrink you use for your connections, but the adhesive-lined type seems to work very well for this application. I should also mention that it is important to thoroughly wash off all flux residue from the wire as it will cause corrosion over time. I am referring to acid flux. I haven't tested this with rosin, but I would assume this would be less of an issue as this is the type of flux used for electronics :)
 
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