Bad wire?

[ncp]

Originally Posted by willk

The blackened cable that I've seen has been completely rotten - even the strength had gone and it was brittle. The problem isn't surface tarnishing (that wouldn't effect the conductivity) - it's the complete degradation of the copper in the wire. Poly will know what the reaction is - is it forming a salt or something?

On that end of the wire, I cut it back 2 inches....black....another 6 inches....black...then another 8 inches...black....

Gave up. It's not worth saving.

[willk]

Originally Posted by ncp

Gave up. It's not worth saving.

Yes. I was posting that more for the future hopefuls who read the thread and tried vinegar as a fix

It takes battery cables very badly. The water seeps up the cable and the corrosion begins. I think the result is "hot spots" which quickly get worse and then the fun starts...

[wiLlfish]

Originally Posted by willk

Poly will know what the reaction is

dat scoch nobjokky duzunt noe iz arrse fromm iz elboe


4Cu + O2 + 4H+ + 4OH = 2CU2O + 4H2O +NaCl = F2U3K2T

[Jizm]

Originally Posted by jyasaki

White vinegar and salt?

While it may clean up the corrosion, I'd be a little leery of a) introducing an acid to what is already a reactive metal, and b) adding more of what caused the corrosion in the first place. Going to be impossible to rinse the stuff out of the strands, in any case.

jky

Like I said, only if you really can't replace it. Neutralise with baking soda or similar after...

[Poly]

Originally Posted by willk

Poly will know what the reaction is - is it forming a salt or something?

Originally Posted by wiLlfish

dat scoch nobjokky duzunt noe iz arrse fromm iz elboe

do you think if I went on one of them RYA first aid courses I would learn some anatomy?

4Cu + O2 + 4H+ + 4OH = 2CU2O + 4H2O +NaCl = F2U3K2T

Not sure I have anything further to add!

But in the interests of pedantry the black stuff is CuO not Cu2O (which is red)! Cu2O reacts with carbon dioxide and or sulphates in air to form Copper Carbonate / sulphate - the green "patina" you get on church roofs etc.

CuO does dissolve in strong acids. But I can't see any advantage in removing anything other than surface corrosion on connectors. Not sure why you might add salt either.

[kerny]

[spartacus]

Originally Posted by ncp

On that end of the wire, I cut it back 2 inches....black....another 6 inches....black...then another 8 inches...black....

Gave up. It's not worth saving.

Had similar issue with a Tohatsu wiring loom. Kept cutting it back to see how far the corrosion went... suffice to say it was goosed! Replaced the lot, and where possible I used tinned cable.

[ncp]

Weekend update:

Sealed the heck out of some of the non-tinned mil-spec stuff that I had and the replaced 3 ft. from my 24v to 12v converter to my 12v distribution panel. GPS and VHF stayed on all day yesterday while out on the water!!!

Though, while I was under dash, I realized that the guy I bought my boat from used 12 gauge to feed the converter with 24v current (don't ask me why he used 12 gauge for 24v 50A in and 10 gauge for the 12v 40A out). That's a little small!!! Need to replace that ASAP before the next outing!!!

[Erin]

Originally Posted by ncp

don't ask me why he used 12 gauge for 24v 50A in and 10 gauge for the 12v 40A out

All depends upon the length of the run. If it was only a few inches then 12 gau might have been ok.

[ncp]

Originally Posted by Erin

All depends upon the length of the run. If it was only a few inches then 12 gau might have been ok.

True. I'm not drawing much with my current house/12v loads (VHF/GPS) so it's probably ok for right now.

Both the runs to/from DC-DC 24v/12v converter are ~3ft or a bit less. But, I want them spec'd for max current.

Using Circuit Wizard - Blue Sea Systems
In: 24v, 50A, 6ft., 3% drop, Variable Load, 105 degrees, engine room checked, it says 10 gauge
Out: 12v, 40A, 6ft., 3% drop, Variable Load, 105 degrees, engine room checked, it also recommends 10 gauge

10 gauge seems reasonable.

[jyasaki]

Originally Posted by ncp

Using Circuit Wizard - Blue Sea Systems
In: 24v, 50A, 6ft., 3% drop, Variable Load, 105 degrees, engine room checked, it says 10 gauge
Out: 12v, 40A, 6ft., 3% drop, Variable Load, 105 degrees, engine room checked, it also recommends 10 gauge

24V@50A input, 12V@40A output?

That implies the you're consuming 1200 watts from your 24V feed, getting 480 watts for your 12V, while burning 720 watts in the converter itself.

You sure about those numbers? It might be, but something sure sounds wrong to me.

jky

[ncp]

Originally Posted by jyasaki

24V@50A input, 12V@40A output?

That implies the you're consuming 1200 watts from your 24V feed, getting 480 watts for your 12V, while burning 720 watts in the converter itself.

You sure about those numbers? It might be, but something sure sounds wrong to me.

jky

Nope, but that's why I ask. I understand V = I x R.

The 24v+ coming from my alternator goes through a 50A circuit breaker beofre getting to the DC-DC converter. So, I assume that's the max that I'd be sizing for. I honestly don't know how many amps the 24v Delco alternator puts out.

My DC-DC converter puts out 40A at 12v per the spec sheet.

[jyasaki]

OK; the breaker is likely oversized (no problem if the wiring can handle it.)

I thought you were working of the specs of the converter, which wouldn't make a lot of sense.

jky