Terminals on heavy battery /starter cable

[lw395]

Couple of problems here:
10mm microbore (from Wickes) has wall thickness of 0.7mm, giving cross sectional area of 22mm², this is equivalent to 2.5mm dia cable.You have a serious bottleneck at the crimp.
Also, compared to copper, solder is a pathetic conductor, you should focus more on physical connection with solder there to hold things in place.

The resistance of a 2cm terminal is likely to not matter in the scheme of things.
But no-name crimps from ebay are likely to be better than home made, for a few pence.

Getting the welder maintenance bloke to put on a proper one still gets my vote when it's practical.

 

[Daverw]

I agree. For about 150 quid it looks like I can renew all the cable from my starter battery to engine in 70mm squared tinned with decent quality fittings. Anchor dragging in a squall is not the time for me to wish I'd spent a little more..

I've just wired from scratch my new windless, cable, all crimps and fittings for less than £50, shop around away from marine suppliers for cable, I have a mate who got it trade, 70% discount, cable prices are a real scam

 

[Daverw]

Lots of effort to save 87p, also copper will work harden when flattened and is better plated after. Perhaps I'm missing something but why bother. I'd rather be out sailing

 

[pvb]

Yes... my bad! I know what you mean though mine is certainly getting to that stage and at 1982 vintage and with a handful of Atlantic circuits under her keel she's showing her age a bit. Its the deck for me that's the killer. There's still about half an inch of teak thickness left but it needs continuous work and ideally I need to re-seat a few planks. I'm pretty much decided now on replacing it with a 'flexiteek' one in a year or two. They do a weathered teak thats a much nicer silvery colour (than some of these hideous orange ones) and they've done my class of boat before so the price if I do the donkey work is only about 4k plus vat. I'm sure it will de-value the boat a little but I've got no plans to move on and I figure even if I changed my mind a smart new replica teak deck got to be worth more than a green leaky real teak one!

One of the visual characteristics of HRs is that they use quite a narrow teak plank. One of the reasons quotes for a new deck are so high is because there are many more planks to fix, and thus there's a massive amount of labour. If you're going to replace with flexiteek, I'd seriously recommend you consider matching the original plank width to maintain the characteristic appearance.

Needless to say, I went for fake teak on my new boat!

 

[sarabande]

Couple of problems here:
10mm microbore (from Wickes) has wall thickness of 0.7mm, giving cross sectional area of 22mm², this is equivalent to 2.5mm dia cable.You have a serious bottleneck at the crimp.
Also, compared to copper, solder is a pathetic conductor, you should focus more on physical connection with solder there to hold things in place.

DT

can you run over the maths again, please ?

I always get the measurements of pipe and tube mixed up.... Ta.

 

[contessaman]

One of the visual characteristics of HRs is that they use quite a narrow teak plank. One of the reasons quotes for a new deck are so high is because there are many more planks to fix, and thus there's a massive amount of labour. If you're going to replace with flexiteek, I'd seriously recommend you consider matching the original plank width to maintain the characteristic appearance.

Needless to say, I went for fake teak on my new boat!

I was impressed with this:

https://www.google.co.uk/search?q=f...UICCgC&biw=800&bih=1280#imgrc=8DpkO9hOInhvNM:

Iooks to be done in the spirit of the original deck wouldn't you agree?
Im fortunate in not having teak on the coach roof like this one and hence I only need the 'island deck' as they call it. Sorry about the thread drift everyone! There's lots of interesting and useful stuff coming g out of this on the cable / terminals front so thanks for all your inputs/ ideas

 

[pvb]

I was impressed with this:

https://www.google.co.uk/search?q=f...UICCgC&biw=800&bih=1280#imgrc=8DpkO9hOInhvNM:

Iooks to be done in the spirit of the original deck wouldn't you agree?

Yes, that looks good. It would look even more authentic if they'd put some staggered fake plank joins in, like the fake teak on my Bavaria.

 

[Lon nan Gruagach]

DT

can you run over the maths again, please ?

I always get the measurements of pipe and tube mixed up.... Ta.

Cross sectional area of thin wall tube (since id is very close to od use base dimension, resultant error is quite small):
Area = thickness * circumference of tube
= thickness * Pi * diameter
= 0.7mm * Pi * 10mm
= 22mm² ish

Equivalent solid cylinder
Area = Pi * radius^2
radius^2 = area/Pi
radius = sqrt(area/Pi)
radius ~= 2.6mm

Oops, should have been 5mm dia, not 2.5 as I posted earlier, but still way smaller than 10mm.

 

[pvb]

Couple of problems here:
10mm microbore (from Wickes) has wall thickness of 0.7mm, giving cross sectional area of 22mm², this is equivalent to 2.5mm dia cable.You have a serious bottleneck at the crimp.
Also, compared to copper, solder is a pathetic conductor, you should focus more on physical connection with solder there to hold things in place.

So what's the problem realistically with this "serious bottleneck"?

 

[sarabande]

Cross sectional area of thin wall tube (since id is very close to od use base dimension, resultant error is quite small):
Area = thickness * circumference of tube
= thickness * Pi * diameter
= 0.7mm * Pi * 10mm
= 22mm² ish

Equivalent solid cylinder
Area = Pi * radius^2
radius^2 = area/Pi
radius = sqrt(area/Pi)
radius ~= 2.6mm

Oops, should have been 5mm dia, not 2.5 as I posted earlier, but still way smaller than 10mm.

Using this online calculator for an annulus..
http://www.calculatorsoup.com/calculators/geometry-plane/annulus.php

I get 27mm² which is 6mm dia for wire.

I agree that thinwall copper is not a good idea.

For a 65mm² battery cable, a 10mm int diameter copper pipe would be fine for a strong crimper, but wall diameter to achieve 75mm² annulus (i.e. equivalent to cable cross-section would need to be 2mm. That sounds like a beefy cable terminator to me !

 

[lw395]

Do we really think the resistance of a terminal about a cm from the wire end to the bolt hole is likely to be critical, just because it's about twice the ohm per metre of the cable?

Bigger issue of using tube for crimping is that plumbing tube is not annealed copper.

 

[Lon nan Gruagach]

Using this online calculator for an annulus..
http://www.calculatorsoup.com/calculators/geometry-plane/annulus.php

I get 27mm² which is 6mm dia for wire.

I agree that thinwall copper is not a good idea.

For a 65mm² battery cable, a 10mm int diameter copper pipe would be fine for a strong crimper, but wall diameter to achieve 75mm² annulus (i.e. equivalent to cable cross-section would need to be 2mm. That sounds like a beefy cable terminator to me !

Well, now thats strange... What numbers did you use? for outer radius 5mm and inner radius 4.3mm I get 20.4mm²

 

[Lon nan Gruagach]

So what's the problem realistically with this "serious bottleneck"?

Do we really think the resistance of a terminal about a cm from the wire end to the bolt hole is likely to be critical, just because it's about twice the ohm per metre of the cable?

Bigger issue of using tube for crimping is that plumbing tube is not annealed copper.

Tesco, innit? every little helps.

 

[pvb]

Tesco, innit? every little helps.

But it isn't even a "little", it's an "infinitesimal"! A perfect example of theory over practice.

 

[sarabande]

Well, now thats strange... What numbers did you use? for outer radius 5mm and inner radius 4.3mm I get 20.4mm²

I must confess to placing total reliance on Wikipedia and the internet rather than doing the number crunching myself as my Godfrey and Siddons four fig tables are in another room, and my slide rule is in a museum at school.

Sticking your figs (I agree) into the boxes on

http://www.calculatorsoup.com/calculators/geometry-plane/annulus.php

I get 27mm², well OH HELL AND DAMNATION I have just given you the inner circumference Doh !

Many Apologies, abases self thrice in direction of DT