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Author Topic: How to make 24v bank? (Cabling wise that is)  (Read 2971 times)
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« Reply #15 on: August 29, 2015, 01:26:14 PM »

I am learning Scruff,
                 Still learning. I flattened ,shaped,drilled and insulated other copper pipe connectors and thought they were hard to beat. No crimping involved and really good contact at the poles.

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« Reply #16 on: August 29, 2015, 01:44:26 PM »

You'd need a precision meter with gold plated probes to register contact resistance of a decent termination. It does become significant though in certain circumstances. Say 20 terminations after the regulator with heavy loading on very low voltage systems as often seen in split bank charging on mobile installations. Not really an issue in houses that don't move.

Good crimping is hard to beat.

Actually stronger than solder when you get up to the hex dies.
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« Reply #17 on: August 29, 2015, 03:09:42 PM »

Its far more accurate to lob a known high current, low voltage supply across your test connection, and measure the voltage drop across the connection.  Say 100a at 6v. Then your 4mohm resistance will show as

100 x 0.04 = 4volts. Quite easy to measure.

Not so easy to maintain 100a steady with domestic kit. We had a 1500 amp power supply when i was working on aerospace connector design. As said, decent crimping is far better than solder. But solder is better than bad crimping! In something like a boat i would solder, as it forms a seal too.


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« Reply #18 on: August 29, 2015, 03:11:34 PM »

Some sums: (please ignore this if you already know it Smiley)

10mm diameter copper pipe is typically 0.7mm wall thickness.
If it was solid rod, it would have a cross-sectional area of 78.54^2 mm.  (pi x r^2 = area) = (3.142 x 5 x 5 = area)
As it is pipe, it has a hole down the middle that is 8.6mm diameter, with a cross-sectional area of 58.09^2 mm.
Subtract the 'hole down the middle area' from the 'solid rod area' leaves you with the area of copper ~ 20.45^2 mm of lovely conductiveness.

Other size pipes can be done in the same manner, bearing in mind the different BS grades of pipe for different uses:

15mm pipe could be 0.8mm wall thickness, so doing the same as above has a Copper CSA of 176.71 - 141.03 = 35.69^2 mm.
22mm pipe could be 0.9mm wall thickness, so doing the same as above has a Copper CSA of 380.13 - 320.47 = 59.66^2 mm.
etc, etc.

These figures are very approximate, but give an idea of what can be done for stationary applications. Like Scruff says, DC doesn't do skin effect. I have made tens of thousands of crimp terminations and they are without doubt the most reliable way of terminating the ends  of stranded wire/cable.
The advantage of using tube is that you don't need a crimp-tool: Squish it, bend it to shape, drill holes, fit heat-shrink sleeve, then pat wallet smugly.

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« Reply #19 on: August 29, 2015, 07:11:34 PM »

100 x 0.04 = 4volts. Quite easy to measure.

oops I meant 0.4mΩ

100 x 0.0004 = 0.04V
times ten for 20 terminations and it's a big loss all the same at 12V. I agree, experimental figures are the most accurate.
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