Anyone using automotive cable for their starter motors?

[facthunter]

I'm sure you would, danny.   Nev

[RFguy]

CRIMP, for sure.  soldering creates a brittle, heat treated joint.  Suggest as high strand count as you can get.
Now, as for wire  :  and, may I quote AC43 : There is no need to speculate.

AC43.13-1B  , https://www.faa.gov/documentlibrary/media/advisory_circular/ac_43.13-1b_w-chg1.pdf

CHAPTER 11 - AIRCRAFT ELECTRICAL SYSTEMS

Section 6 : Aircraft Electrical Wire Selection.

Section 14 : Terminal Repairs.

11-174  General

11-178 Crimp on Terminal Lugs 

I strongly suggest users modify and maintain their LSA airplane electrics to AC43.13. There is about 20 good pages to read between Section 6 and Section 17.

That been said, I'd suggest a high strand count  cable with insulation good for fire temps, and appropriate crimp lugs for that cable, and a suitable crimp tool , or fashioned die in a vice to generate the impression.

Edited April 16, 2023 by RFguy

[Area-51]

Design the system for 400VDC then you can use lighter gauge wire all over... but the aeronaut prices will be the same... maybe more because there is less material weight and an extra digit in the voltage level; so higher price 🤷🏼‍♂️

[facthunter]

Surely you jest. 400 volts is not safe with people and likelihood of arcing. 110 volts DC is used in parts of some aircraft systems Most modern (larger) ones use alternating current and that has synchronicity issues.  BIG amounts of electrical power though.   Nev

[spacesailor]

A little more !.

I have just seen a '' crimping '' device made from an appropriate size nut , cut into two . the halves put around the  crimpee then squeezed in a vice .

It gave a fantastic ridged crimped finish , It looked as good as professional product .  ( as compered to a two sided crimp ) .

spacesailor

 

 

[RFguy]

Maybe, except there are many variations on crimp connectors- many crimp lugs require to get pinned from underneath- one side is a hemisphere (sortof) and the other side a square pin push
Depends if you are trying to get a swaged joint, etc - many variations. 

 

Before substituting a makeshift die, try and get a look at the real tool.

[spacesailor]

I bought a set of two ' hand crimpers ' , that were expensive marine grade . ( a metre & a half long  ).

Same as those cheap electrical hand crimpers , only squeezed oposite sides of the ferrule. 

Lots of room for corrosion. 

spacesailor

[facthunter]

Bare fine copper wire ='s verdigrese add a dissimilar metal and you are worse off. How do you seal it?   Nev

[danny_galaga]

58 minutes ago, facthunter said:

Bare fine copper wire ='s verdigrese add a dissimilar metal and you are worse off. How do you seal it?   Nev

If it's properly joined, crimp or solder, then it's sealed. You can only get the tiniest bit of corrosion around the edge of the lug. Not saying it won't happen. Most likely if it is getting wet, particularly sea water. Then you have a nice electrolyte in  the equation.

 

When I was an apprentice I remember going out to a job where another apprentice had put brass bolts on an aluminium hull. Owner wasn't best pleased and told the shop to come back and fix it. It got my curiosity. When I went home I put a piece of copper and a piece of aluminium into a glass of salty water and measured it. It was generating something like 0.6 (from memory) volts! That's pretty impressive.

 

I have determined that I will try and keep my aircraft out of the ocean 😀

 

Edited April 20, 2023 by danny_galaga

[Old Koreelah]

I’m relocating my LiFePO4 battery, so the extra metre of cable needs to be lightweight.
Until recently all my research had convinced me it was safe as houses, then a powered sailplane pilot reported his Li battery had been cooked from over voltage, due to the regulator failing. 
Mine will now sit under a fire-proof box in my forward floor window bay, so it can be ejected if it plays up. 

 

I have Al power cable, strands about 3mm.

How to prevent corrosion at the join? Seal completely in silastic to exclude air and water?

 

[onetrack]

Many silicon sealants contain acetic acid which etches aluminium, so it pays to avoid these types. They can be recognised by their vinegar-like smell (acetic acid) when curing.

It's preferable to use a neutral-cure industrial silicone sealant/adhesive where metals are involved. Silastic works well on glass and plastics, because the acid etch assists in adhesion.

I have a preference for a good-quality polyurethane sealant/adhesive, which still stays flexible when cured. Bostik make a good range of these types.

 

Be aware that aluminium wire has a very high tendency to fracture with vibration over a period - so if used, it must be well secured, and it can't be used in positions when regular flexing happens, such as between engine and frame.

 

Edited April 20, 2023 by onetrack

[facthunter]

When you cut up old magneto secondary windings which are protected initially by a thin coating on each wire then sealed in a special  material and epoxy under a vaccuum, the windings look like old coarse green hair and leak the 30.000 volts they have to handle and then run hot and fail or sometimes they go black from a large short at one time usually because a lead has come off and if there's no safety gap.  Nev

[danny_galaga]

1 hour ago, facthunter said:

When you cut up old magneto secondary windings which are protected initially by a thin coating on each wire then sealed in a special  material and epoxy under a vaccuum, the windings look like old coarse green hair and leak the 30.000 volts they have to handle and then run hot and fail or sometimes they go black from a large short at one time usually because a lead has come off and if there's no safety gap.  Nev

I'm not sure what you are driving at. Should we not have cables at all? I believe the Rotax is almost impossible to hand start 😄

[facthunter]

Just that it's hard to stop copper wire from corroding This is an example where a vaccuum is used when sealing it and it  still fails.(corrodes).  Who would suggest we don't have cables? Certainly not ME but corrosion, specially at the crimp must be considered and dealt with.  I'd see best marine practice as appropriate.  Nev

[danny_galaga]

What's the point? How long did that magneto go for? Like I say, I'll try not to put him.down in the sea 😄

[facthunter]

Not more than 20 years generally but they have to be reliable. You don't wait till they fail like all things on planes.. Nev

[KRviator]

To answer the OP's question - I used 0 Gauge cable from Jaycar and crimped terminals on the RV for both starter current and engine ground and used a double layer of heat shrink over the ends, one about 6" long, the other 3" on top. Suitably supported with Adel clamps, I've not had any issues in 5 years and nearly 200 hours.

[Siso]

Welding leads from a welding supplier make good jumper leads. Not sure the insulation is made of. lots of very fine wire to make it flexible. Available in different sizes.

 

[facthunter]

You could always duplicate a lead to  gain the  extra current compatibility. I recommend the earthing wire be duplicated or you throttle cable might become a substitute Nev

[danny_galaga]

14 minutes ago, facthunter said:

You could always duplicate a lead to  gain the  extra current compatibility. I recommend the earthing wire be duplicated or you throttle cable might become a substitute Nev

On the Rotax, they use a motorbike starter. The consequence being there are two superfluous lugs hanging off the back of the starter. Negative is going straight from the battery to one of those lugs 🙂

[facthunter]

Hasn't the airframe got a negative to the engine/ battery?   Nev

[danny_galaga]

21 minutes ago, facthunter said:

Hasn't the airframe got a negative to the engine/ battery?   Nev

It will have what I want it to have- negative straight from the battery to the starter (least amount of resistance you can have for the highest current) and a negative lead from the battery to the negative bus bar on my instrument panel  🙂

[danny_galaga]

Oh my god, such an epic struggle to get a few cables made. My auto electrician would have been fine, but the size cable I want to use they don't carry. They would have to order ten metres minimum. How about the motorcycle shop down the road? Good point. There s a row of them. First one I asked, he  really wasn't listening. What bike is it for? I tried again  to tell him I need cables  made. But what bike is it for? Geez, ok it's for a BMW f650. Sorry we only do British bikes.

 

DAFUQ? I said 'what I'm asking is can you make up some cables for me'. No sorry. 

Second shop had some stuff kick around but he didn't know what any of it meant. He had no idea what I was saying. He didn't know what the sizing meant. I said imagine it's for a Harley Davidson. I don't know what that means... I got him to show me the cable he had. Looked a bit small.

Passed a boat shop and thought that should be right up their alley.they were nearly as vague as the second bike shop.

 

I didn't tell any off these guys it's for an ultralight as I get mixed results.

 

I might as well have been asking for a window winder for a space shuttle. In Swahili.

 

In all cases they are greeting the customer ready to say no, instead of being ready to help. This is why I buyso much stuff online nowadays, I can't be arsed explaining myself to disinterested people. Of all ages in today's case I might add. It's not just a youth thing.

 

So I'm about to order some 3 b & s cable online and then I'll take it to my sparky .

Edited May 10, 2023 by danny_galaga

[facthunter]

In the past I've got all mine from REPCO.   Nev

[spacesailor]

Yes,  But,

For what Car ?

That's the response I get .

Tell them it's a ' home built '  car like  ' Peter Brock ' made .  ( big hills to climb) !.

It should wake them up a little .

spacesailor