Anyone using automotive cable for their starter motors?

[danny_galaga]

Particularly the 'motorbike sized' starters like Rotax and Jabiru. Just curious. Would be much easier to set up with automotive than tefzel. You can get pre-made lengths easily enough. Obviously a drawback is it would be more likely to create smoke in a dead short situation. My thought is that with an isolator, it shouldn't be a problem. The run is quite short in my plane too, which also reduces the risk of a short.

 

 

[facthunter]

IF the cable gets hot make it bigger. That includes the earthing too. I would prefer soldered ends to crimped. Use resin cored solder. Nev

[danny_galaga]

20 minutes ago, facthunter said:

IF the cable gets hot make it bigger. That includes the earthing too. I would prefer soldered ends to crimped. Use resin cored solder. Nev

Fully agree. We always soldered our cables with gas. The flux was a paste from memory. 

[facthunter]

I got caught with one set of ends which turned out to be stainless steel and would not solder with tin-lead.  Nev

[skippydiesel]

1 hour ago, facthunter said:

IF the cable gets hot make it bigger. That includes the earthing too. I would prefer soldered ends to crimped. Use resin cored solder. Nev

I prefer crimping because I spent some time with NSW Fisheries and saw how readily soldered joints seemed to "evaporate" in a saline environment.

 

Not suggesting many of our aircraft operate in salt laden air but the lesson on how quickly & completely solder can seem to just disappear, will always influence my choice of electrical connation system.

 

Crimping done well makes a very secure and durable connection. Done badly & the security goes out the window, along with the electrical conductivity.

 

I guess a combination of solder + crimp would be the ultimate but seems at tad overkill.

[spacesailor]

I never trusted ' crimp t ' joints , as there is Always an air gap between the copper strands . Solder fills All the air spaces .  ( and some crimpers only squeeze opposite sides ).

But why , do ( some ) manufacturers put batteries in with the leads going the LONG way around to the starter .

You should be able to BUY the correct sized cable for whatever the needs are , then the end fittings to suit .

BUT Why do you always insist on cable . a lot of trucks use a solid ' strap ' , especially on the ' preheater ' , were that strap has holes to suit the location of the heater plugs  .

spacesailor

[danny_galaga]

When you say some manufacturers, do you mean aircraft manufacturers? It's certainly best to keep the lead as short as possible.

 

You need cable going to a starter motor. It needs to be flexible.

[Old Koreelah]

Copper cable is heavy. Aluminium cable is an excellent conductor and light, but can it be “soldered”? How do you avoid corrosion issues where aluminium is joined to copper?

[danny_galaga]

That's getting a bit academic. I'm not building a 11kv transmission tower!  Everyone uses copper cables for starter motors. so will I. 

 

Lucas sometimes used aluminium for field windings in their starters. The copper tag of the  brushes were spot welded on. If you had to replace them, normally you would cut off the brush, leaving a bit of the copper tag behind. Then bind the new brush on with a single stand of copper wire and solder.

 

One place I worked at did a lot of vintage stuff, and someone had a roll of 'aluminium' solder. Not sure what it was made from. Apparently unobtainium, because you couldn't buy it anymore. But it could solder copper to aluminium! I never used it though.

Edited April 14, 2023 by danny_galaga

[bushcaddy105]

Heavy duty jumper lead cable. Many, many strands of thin copper so flexible. Soldered ring terminals at ends to suit. Glue lined heat shrink over terminals to insulate and keep moisture out.

[Kiwi]

I wouldn't use aluminium cables, Piper issued a SB years ago about aluminium starter cables,  can get a STC to replace them with copper. 

[Old Koreelah]

Why?

[danny_galaga]

1 hour ago, Old Koreelah said:

Why?

Without looking it up, I wouldn't be surprised if it's to do with fatigue. Aluminium wire I reckon would crack easier than copper. I feel it would have less flex I had no idea it was being used for starter motor cables though 😲

 

[Kiwi]

Risk of electrical fire was the part that caught my attention. 

[Old Koreelah]

36 minutes ago, danny_galaga said:

Without looking it up, I wouldn't be surprised if it's to do with fatigue…

Thanks Danny. That’s the only downside I can see and it should be easily fixed if the aluminium conductors are sheathed and well fixed to stop the effects of vibration.

 

That Piper SB in Kiwi’s post seems to blame corrosion at junction points for the risk of fire, so that’s my main area of interest: the safest (and lightest) way to join fixed aluminium cables to flexible copper ones.

[Area-51]

Everything should be made of gold; zero corrosion, excellent conductivity, remains soft and pliable if 24ct... and when you pay the aeronautical related prices it will be good value for price!! ... and if you get grounded in a war zone you can pull the cable and use it to barter for your life where the guy in the cessna with copper cables won't

[facthunter]

Moisture and two dissimilar metals and you will have a problem.  nev

[Ian]

Aluminium can be worthwhile from a weight and cost perspective however you need to be mindful of its weaknesses. The piper issues appears to have been with bimetallic corrosion, if you really want to save weight look at lithium batteries first.

You can buy aluminium to copper crimps. Bimetal corrosion is still an issue however oxidation within the cable lug is prevented by protecting the internal surface with a specific grease with a very high dropping point.

[danny_galaga]

Case closed. I was curious if anyone was using automotive cable. Turns out some people are. So will I 🙂

[facthunter]

Have the cable long enough to be able to cope easily with any possible movement the engine will experience. Avoid sharp bends that "work". Copper work hardens too.   Nev

[spacesailor]

And dip / solder the terminals with GOLD ! .

None corrosive  and no electrolysis. 

Aluminium cables at there best.

spacesailor

[facthunter]

Gold melts at about 400 C above the temp  aluminium melts at and 20 C below copper melt point.  Nev

[danny_galaga]

2 hours ago, facthunter said:

Have the cable long enough to be able to cope easily with any possible movement the engine will experience. Avoid sharp bends that "work". Copper work hardens too.   Nev

Don't forget I used to be an auto electrician, so I will definitely observe those things 🙂

[spacesailor]

Observe the fact '' the shortest length '' has less loss .

so you need less thickness , for the same amperage .

spacesailor

[danny_galaga]

4 hours ago, danny_galaga said:

Don't forget I used to be an auto electrician, so I will definitely observe those things 🙂