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I bought a thermal-imager and ...

Brucey said:
Can you fit two 4/0s? Not sure if it was this thread where narrower lugs were thought to be needed. Then no worries at all about heating.
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I started that thread. I got a chance to test my MPII 3000 12V 2x120 today and it actually fits 2x4/0 standard lugs just fine. I used someone else's picture and assumed all MPII's were the same. They are not.

And to your point, I could just double up my 4/0, but 2/0 is sooooo much easier to work with. Especially for very short runs.
 
corn18 said:
I started that thread. I got a chance to test my MPII 3000 12V 2x120 today and it actually fits 2x4/0 standard lugs just fine. I used someone else's picture and assumed all MPII's were the same. They are not.

And to your point, I could just double up my 4/0, but 2/0 is sooooo much easier to work with. Especially for very short runs.
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Not sure what cable you are using but the windy nation cable is pretty supple.
 
corn18 said:
This is very frustrating. One chart says 90 deg 4/0 is good for 260A and one chart says 105 deg 4/0 is good for 440. Then I go to the Blue Sea Systems calculator and it says 90 deg 4/0 is good for 385A and 105 deg is good for 445A. Then I go to the Southwire calculator and it says 90 deg 4/0 is good for 455A in free air (whatever that means) and 90 deg 4/0 is good for 260A in conduit/direct burial.

That is quite a range of ampacity for 90 deg 4/0 cable: 260A-455A. The lower number is in conduit, the higher number is free air.

My MPII draws 325A @ 12V at max power. Victron recommends 2x2/0 cable for it. 2x2/0 90 deg cable in conduit is rated for 195A each, so 390A total. A single 90 deg 4/0 cable in conduit is rated for 260A. Seems like I would be way better off using 2x2/0 vs a single 4/0 for my MPII. I can tell you without a doubt that my 105 deg 4/0 cable I am currently using gets pretty warm with the MPII at max power.
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It won't help you now, but this is why I try to convince people to build 24 volt systems instead of 12 volt systems.

As far as how to move a lot of 12 volt pushed amps into an inverter - it is always harder than it seems like it should be. There just is not much voltage drop available to push those amps along compared to at 24 volt, loosing 1 volt in drop is not as big of deal.

There are two steps to selecting a wire:

1) Use an ampacity chart ( not a calculator ) and find the smallest allowable wire size.

Here is the one on the cerro wire page, but it is an NEC chart so posted all over.

www.cerrowire.com

Cerrowire Resources - Ampacity Charts

Ampacity is the maximum current that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Cerrowire's ampacity chart helps calculate the load requirement for a circuit.
www.cerrowire.com www.cerrowire.com

Just as an example, suppose you want to use dual wires to feed the inverter, then each will carry about 150 amps.

So now go to the absolute most left hand column of temperature rating for wire that lists the ability to carry 150 amps. In this case it is 1/0 wire. This comes from the ability of the wire to dissipate heat from inside of it. So this is the absolute smallest wire that you should use for 150 amps.

2) Now go to a wire size calculator and use it to "double check" if you should go up in size due to exceeding the 1 % loss.

Using the bluesea calculator, just because I am more familiar with it:


Using 150 amps, 20 ft round trip wire length path, and 1 % loss, it could not reach a result.

So I increased this to 3% and it came back with 1/0 wire.

____________________

So I agree with you that dual 1/0 is about as good as you are going to get for a V 3000 / 12 system.

Keep in mind that the wire lugs are the most common location for imperfections. I make a fair amount of 10 and 14 awg, some 6 awg.

When I need higher current wires, I just make a prototype using 10 awg and then order from a quality wire supplier. I am confident that I cannot make a 1/0 wire that even comes close to what they can do in quality or price.
 
corn18 said:
This is very frustrating. One chart says 90 deg 4/0 is good for 260A and one chart says 105 deg 4/0 is good for 440. Then I go to the Blue Sea Systems calculator and it says 90 deg 4/0 is good for 385A and 105 deg is good for 445A. Then I go to the Southwire calculator and it says 90 deg 4/0 is good for 455A in free air (whatever that means) and 90 deg 4/0 is good for 260A in conduit/direct burial.

That is quite a range of ampacity for 90 deg 4/0 cable: 260A-455A. The lower number is in conduit, the higher number is free air.

My MPII draws 325A @ 12V at max power. Victron recommends 2x2/0 cable for it. 2x2/0 90 deg cable in conduit is rated for 195A each, so 390A total. A single 90 deg 4/0 cable in conduit is rated for 260A. Seems like I would be way better off using 2x2/0 vs a single 4/0 for my MPII. I can tell you without a doubt that my 105 deg 4/0 cable I am currently using gets pretty warm with the MPII at max power.
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Wat model u use .
This is the specs cable for the victron multiplus 2
 

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crossy said:
who remembers VGA being 320x200 in 256 colours, and we all thought it was wonderful?
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Great, thanks for that... you just reminded me that some of us are old enough to remember the introduction of CGA over monochrome screens :eek:👵
 
SeaGal said:
Great, thanks for that... you just reminded me that some of us are old enough to remember the introduction of CGA over monochrome screens :eek:👵
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I still remember playing asteroids in my sharp mz! people think their old when they used to use floppy disks funny young uns.
 
SeaGal said:
Great, thanks for that... you just reminded me that some of us are old enough to remember the introduction of CGA over monochrome screens :eek:👵
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Remember Alley-Cat on the PC?? My downfall was invariably the dog.

CGA had weird colours!!

dosgames.com

Alley Cat game at DOSGames.com

Even though this is an extremely old game (1984!) and even though it features archaic 4-color CGA graphics, it still can be fun to play. AlleyCat has ...
dosgames.com dosgames.com

1720777481983.png
 
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crossy said:
Remember Alley-Cat on the PC??
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PC?!! My first computer had 256 bytes of RAM and I had to program it in hex. My dad helped me learn to solder it together. Yep, am that old :) Floppy discs (8" ones) came after I upgraded from a 300 baud cassette program storage system.
 
The thread turned into memoirist pool ... I did work on IBM System/360 [MFT]. Winchesters 3380 was 2x200 MB 12" size and heavy, used a cart. Displays (!) are monochrome alphanumeric ....
ibm-360-44-lcm.jpg
 
corn18 said:
This is very frustrating. One chart says 90 deg 4/0 is good for 260A and one chart says 105 deg 4/0 is good for 440. Then I go to the Blue Sea Systems calculator and it says 90 deg 4/0 is good for 385A and 105 deg is good for 445A. Then I go to the Southwire calculator and it says 90 deg 4/0 is good for 455A in free air (whatever that means) and 90 deg 4/0 is good for 260A in conduit/direct burial.

That is quite a range of ampacity for 90 deg 4/0 cable: 260A-455A. The lower number is in conduit, the higher number is free air.

My MPII draws 325A @ 12V at max power. Victron recommends 2x2/0 cable for it. 2x2/0 90 deg cable in conduit is rated for 195A each, so 390A total. A single 90 deg 4/0 cable in conduit is rated for 260A. Seems like I would be way better off using 2x2/0 vs a single 4/0 for my MPII. I can tell you without a doubt that my 105 deg 4/0 cable I am currently using gets pretty warm with the MPII at max power.
Click to expand...

The capacity of a wire to carry current is influenced by its sheath and the gauge of the individual strands within each wire.

The pure, simple cross-sectional area of copper determines how much current it can carry. However, this theoretical value is much higher than the actual rated value because it doesn't account for heat and cooling.

Airspace between the wires plays a role too—the finer the wires, the more airspace there is to retain heat. Therefore, for heating, thicker wire strands are better.

Thick wires are hard to bend, and when you do bend them more than a few dozen times, the copper gets brittle and can fracture. This is why single-stranded wire is used in fixed installations where there is no movement or vibration.

Finer wires can be bent many times without becoming stiff and can make tighter radius bends. Think of welding wire, for example.

The temperature rating of wire is also important. Different sheathing materials have varying abilities to dissipate heat and withstand repeated bending. In general, wire is rated in degrees Celsius for how hot it can get before failure.

Resistance to external factors is another consideration. Some sheaths can resist oil better than others, making them suitable for engine compartments. Others are better at resisting higher voltages.

For instance, 105°C welding wire consists of very fine strands in a rubber sheath, making it highly bendable.

THHN (Thermoplastic High Heat-Resistant Nylon-coated) wire is rated for high temperatures and is commonly used in dry locations. Comes in 75c and 90c versions

THWN (Thermoplastic Heat and Water-Resistant Nylon-coated) wire, on the other hand, is suitable for both wet and dry locations due to its water-resistant properties. Comes in 75c, 90c, and 105c versions.

There are other coatings that can hit 250c or more.


And when you shove it into conduit, or conduit on a roof, or in free air there are adjustments that get made.
 
SeaGal said:
Great, thanks for that... you just reminded me that some of us are old enough to remember the introduction of CGA over monochrome screens :eek:👵
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HA, I do recall the old compact computers, 30lbs, 4 inch amber screen or black and white with a keyboard wired to it... then the TRS-80 with the built in 9 inch screen, then the apple IIe with the separate 11inch screen that was monochrome or color... then came the IBM PC with a generic monitor.

And I spent HOURS loading flight simulator from a cassett on a timex sinclare 1000 with the memory expansion pack only to have the MEP fall off when I pressed one of the membrane switches to hard.
 
robbob2112 said:
HA, I do recall the old compact computers, 30lbs, 4 inch amber screen or black and white with a keyboard wired to it... then the TRS-80 with the built in 9 inch screen, then the apple IIe with the separate 11inch screen that was monochrome or color... then came the IBM PC with a generic monitor.

And I spent HOURS loading flight simulator from a cassett on a timex sinclare 1000 with the memory expansion pack only to have the MEP fall off when I pressed one of the membrane switches to hard.
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I have all of those in the next room right now. I so wanted to make a computer museum with all of the equipment I collected over the years but no one seems interested these days in seeing the stuff.
 
Crowz said:
I have all of those in the next room right now. I so wanted to make a computer museum with all of the equipment I collected over the years but no one seems interested these days in seeing the stuff.
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There are already a dozen or so museums online. Only a couple of the ancient units are worth more than a bottle of soda. Like an original working Apple in the wooden case goes for a few hundred thousand. Some of the early TRS-80 Model I computers are worth $50... and some of the Heathkit Z80 versions are super rare... I repaired one for my maintenance officer when I was stationed in Guam back in '92
 
robbob2112 said:
There are already a dozen or so museums online. Only a couple of the ancient units are worth more than a bottle of soda. Like an original working Apple in the wooden case goes for a few hundred thousand. Some of the early TRS-80 Model I computers are worth $50... and some of the Heathkit Z80 versions are super rare... I repaired one for my maintenance officer when I was stationed in Guam back in '92
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Ive got all of those except the apple one in the wooden case.
 
Crowz said:
Ive got all of those except the apple one in the wooden case.
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Sell them all and you can sponsor happy hour someplace...

Buy seriously, if you have them all in working order and want to part with them check ebay and see what they actually sold for.

A friend of mine has a used Cray computer in his basement that he got from a university when he was doing some work for them. All he was missing the last time I checked was some of the cabling to hook it up... Looks like a 4ft tall ceramic tower surrounded but wire-wrap links and it has a borosilicate glass tube that sits over it, something to do with cooling. Each one was hand built and cost millions.
 
Crowz said:
Ive got all of those except the apple one in the wooden case.
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Was watching one collector show and the one guy had ALL the Macs including the original model, and a bunch that were sealed in original packaging. Just mind boggling collection.
 
robbob2112 said:
Sell them all and you can sponsor happy hour someplace...

Buy seriously, if you have them all in working order and want to part with them check ebay and see what they actually sold for.

A friend of mine has a used Cray computer in his basement that he got from a university when he was doing some work for them. All he was missing the last time I checked was some of the cabling to hook it up... Looks like a 4ft tall ceramic tower surrounded but wire-wrap links and it has a borosilicate glass tube that sits over it, something to do with cooling. Each one was hand built and cost millions.
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Sadly performance wise prob outperformed by his smartphone. Curious how much power that baby takes to power up won't be cheap unless he has a whole lot of solar
 
I think the environmental required to run it for more than 30 seconds without burnout would cost more than running his whole house AC for a week.

And outperformed by my calculator from 25 years ago that I used in college. -- HP 48gx -- luves me some RPN
 
Could not afford a K & E slide rule during college, Hemmi was good enough for me.
 
SeaGal said:
I want to see :)


I remember being one of the first at school to have a calculator, mid 1970's - a Sinclair Scientific which had fixed mantissa and RPN. I loved it when boys asked to borrow it and then came back flummoxed and complaining it didn't have an '=' button. :ROFLMAO::ROFLMAO:🤷‍♀️

en.wikipedia.org

Sinclair Scientific - Wikipedia

en.wikipedia.org en.wikipedia.org
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I bought TI59 that was going for $300's back in the 80's brand new at the time for $13 :)

It was a montgomery ward store in montgomery and they had mis-priced it in the paper for $13. I was all over that. They weren't going to let me have it at first but my stepdad was with me and between the two of us we pitched enough of a fit they sold it to me for $13. They were NOT happy.
 
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