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SolarSyonyk

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Message 70728 - Posted: 3 Apr 2024, 20:19:27 UTC - in response to Message 70726.  

If only I could simply have the computers suspend (or just pause Boinc) when battery voltage is under x. Sounds like a very simple thing, but unless you're a programmer, impossible.


I can think of half a dozen ways to do it. But I'm a programmer, and I operate in the Linux ecosystem.


Do you mean 5kW peak? That's not very much.


Yes. I've got 5200W of panel hung for my office in various orientations. Which is an 8' x 12' shed of about 86 square feet internal floor space (8 square meters, if you prefer).

The house system is 15.9kW of panel, though optimized for "long solar day" production vs "peak kWh per panel kW," given what I expected to happen with net metering agreements out here.

... plus another kW of panel on a solar trailer.


If it's only 5kW peak it shouldn't be far more. But then you bought it a while ago and prices are plummeting.


Yes, the bulk of my system was built 8 years ago. I added panels a few years ago (2019 or so?) with a small test A-frame before I launched into building the large house A-frames. For a DIY, code compliant, ground mound, grid tie solar install around here, $1/W is doable (I know someone who's done that), but batteries are just expensive.


The only setting I have on my ones is "power limit". I guess that would do the job, I've never tried putting it under the standard "0%". I only raise it to max (usually +20% or +50%). The +50% one then immediately melted the power connector, so I had to solder the wires on.


That adds a LOT of power consumption for only marginally additional compute power. I'd be surprised if you got more than about 10-15% extra compute from the 50% bump in power limit. If you're power limited, go the other way. I run my 2080 (240W nominal power limit) at 125W quite a bit of the time, and it definitely isn't halving compute power.
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Message 70730 - Posted: 3 Apr 2024, 21:19:59 UTC - in response to Message 70728.  

I can think of half a dozen ways to do it. But I'm a programmer, and I operate in the Linux ecosystem.
Know where I could find Windows instructions/people?

The house system is 15.9kW of panel, though optimized for "long solar day" production vs "peak kWh per panel kW," given what I expected to happen with net metering agreements out here.
In the UK, they pay you about a seventh of the money to sell them power as you buy it for. So not worth doing. Best to store it in batteries and screw them.

For a DIY, code compliant
So much cheaper to ignore rules.

ground mound, grid tie solar install around here, $1/W is doable (I know someone who's done that), but batteries are just expensive.
Not so bad now, I can get LiFePO4 for just under £2/Ah at 12.8V. They claim 6000+ cycles to full depth of discharge (some companies say don't do that, but this one says just not to leave it under 5% charged for an extended period).

That adds a LOT of power consumption for only marginally additional compute power. I'd be surprised if you got more than about 10-15% extra compute from the 50% bump in power limit. If you're power limited, go the other way. I run my 2080 (240W nominal power limit) at 125W quite a bit of the time, and it definitely isn't halving compute power.
I was going by MSI Afterburner graphs. It was throttling the clock when there was not enough power. The amount of power added appeared to be similar (I didn't do any precise calculations) to the extra clock speed - remember I was changing a limit, not constant usage. The power used doesn't change at all unless it's throttling.
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Message 70732 - Posted: 3 Apr 2024, 23:04:29 UTC - in response to Message 70730.  

Know where I could find Windows instructions/people?


Not a clue. My experience with Windows for the past 6 years doesn't extend beyond "Installing Windows 10 in a VM to infrequently run some Windows-only software." I can't even interact with it as an operating system anymore, since Microsoft seems to specialize in "changing things, removing functionality, and adding more ads or MSN articles." It's fine, you just have to modify this registry key to get the old functionality back!

If you can export the battery system SoC somewhere that the machines can access it, I'm sure it would be easy enough to write some scripts to poll for that and shut down, or have a Wake on LAN/Remote Sleep Command machine that manages it. I've just been going away from automation as I find my life easier and simpler without bothering with it. I recently removed the last bits of "smart" in my "smart thermostat" by removing its internet connection, because I don't use any of those features, and every other "clever feature" is has is about 50% too clever to be useful. My wife raising the temperature some Tuesday afternoon because one of our kids is taking a bath doesn't mean that the temperature needs to go up every Tuesday afternoon from there on out.


In the UK, they pay you about a seventh of the money to sell them power as you buy it for. So not worth doing. Best to store it in batteries and screw them.


It really depends on the system, the local net metering agreements, and the costs. I'm grandfathered into a kWh for kWh plan until 2045 with my grid-tie house system. Newer installs (at least where I am) get paid about half of the retail rate for exports most of the year, but about 1.5x the retail rate during "peak summer hours" for a few months of a year, which encourages the sort of system I built - east-west facing panels, though one could be fine with just southwest facing panels too. Given our power rates and the costs of UL listed energy storage systems out here, it's hardly worth putting in batteries with a grid-tie system for that reason alone.


So much cheaper to ignore rules.


Indeed! And your power bill goes to $0, too, when the power company disconnects you from the grid for unlisted generating equipment connected to it, which is explicitly listed as an option they have in the relevant rate schedules to me. If they find unapproved generation attached, and there are no suitable disconnects, they'll just take the meter until you sort it out to their satisfaction.

We've gone over this before, and I find nothing interesting about re-litigating it. You prefer to ignore the rules and build as cheaply as possible, my social group and I prefer to build better-quality-than-professionals sort of stuff for radically less money than it pays to get someone to slap it together. It's not hard to do it right, not significantly more expensive in materials, and it tends to both perform better long term and avoid some of the more energetic failure modes that seem to get YouTube views.


Not so bad now, I can get LiFePO4 for just under £2/Ah at 12.8V.


Bare cells, or complete packs with BMS?

The stuff I'm using now (EG4-LLs, LiFePO4) looks to be around US$3.50/(12.8V*Ah), which looks like about £2.75? That's UL listed 4U packs, 400Ah (mine are configured as 48V/100Ah), full BMS, 10 year warranty. I've only had my set in for about 6 months, and they're as staggeringly boring as I'd hoped.


The amount of power added appeared to be similar (I didn't do any precise calculations) to the extra clock speed - remember I was changing a limit, not constant usage.


Sure, but unless your workload is purely register bound, it doesn't scale performance with clocks. Memory access latency tends to limit a lot of GPU workloads.

In any case, a typical DVFS curve (dynamic voltage and frequency scaling) means that the last few MHz use quite a bit more power - the system has to crank the voltage up. I believe power consumption, handwavingly, scales linearly with frequency, and with the square of voltage - so that extra little bit of voltage uses a lot more watts per unit incremental compute per time.

If you're power limited, underclocking/undervolting (or just reducing the power limits, which gets you the same thing on any modern bit of silicon) will improve compute per joule substantially.
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Message 70735 - Posted: 4 Apr 2024, 17:14:45 UTC - in response to Message 70732.  

My wife raising the temperature some Tuesday afternoon because one of our kids is taking a bath doesn't mean that the temperature needs to go up every Tuesday afternoon from there on out.
Never understood why people need to be warm to take a bath. Cold temperatures are actually very good for your health.

We've gone over this before, and I find nothing interesting about re-litigating it. You prefer to ignore the rules and build as cheaply as possible, my social group and I prefer to build better-quality-than-professionals sort of stuff for radically less money than it pays to get someone to slap it together. It's not hard to do it right, not significantly more expensive in materials, and it tends to both perform better long term and avoid some of the more energetic failure modes that seem to get YouTube views.
In that case, yes, you have to use their equipment, but that raises the price so much it ain't worth it. I do it my way with my batteries and they don't get my power.

As for safety, that's for girls.

Bare cells, or complete packs with BMS?
Complete. 12.8V 280Ah for about £500. Surprisingly large and heavy, similar to lead acid! I thought LiFePO4 was smaller and lighter?

If you're power limited, underclocking/undervolting (or just reducing the power limits, which gets you the same thing on any modern bit of silicon) will improve compute per joule substantially.
I'll probably look into that once they're up and running on solar. At the moment I don't care about power usage.
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Message 70741 - Posted: 4 Apr 2024, 22:25:58 UTC - in response to Message 70735.  

Never understood why people need to be warm to take a bath. Cold temperatures are actually very good for your health.


I've no problem with it personally. I'll not fault my wife for raising the temperature up a bit with a 1 or 2 year old for bath time.


As for safety, that's for girls.


Uh... okay. Cool. I'll try not to burn down the house with my wife and kids in it, for the girls in it.


Complete. 12.8V 280Ah for about £500. Surprisingly large and heavy, similar to lead acid! I thought LiFePO4 was smaller and lighter?


It's smaller and lighter, especially if you're looking at derating for temperature and such. Just not as much as most people assume.

The 12.8V/400Ah EG4-LL is just under 100 pounds. The Trojan SPRE 06-415s are a similar rated capacity (somewhat less in practice, but they're broadly close), and a pair of them to make a 12V system would be 236 pounds. So, slightly more than twice as much for a similar capability.
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Message 70751 - Posted: 5 Apr 2024, 19:49:41 UTC - in response to Message 70741.  

Never understood why people need to be warm to take a bath. Cold temperatures are actually very good for your health.
I've no problem with it personally. I'll not fault my wife for raising the temperature up a bit with a 1 or 2 year old for bath time.
Age is irrelevant. Some people bathe their babies in cold water to boost their health.

As for safety, that's for girls.
Uh... okay. Cool. I'll try not to burn down the house with my wife and kids in it, for the girls in it.
They are more important than you?

And we go overboard with safety. Obvious safety is common sense and doesn't need legislation. I mean seriously, warnings on chainsaws not to stop them with your genitals?!

Complete. 12.8V 280Ah for about £500. Surprisingly large and heavy, similar to lead acid! I thought LiFePO4 was smaller and lighter?
It's smaller and lighter, especially if you're looking at derating for temperature and such. Just not as much as most people assume.
I was going by the numbers on the side before any deratings for DOD etc, same V and Ah I thought ended up about half the size and half the weight. I measured it once for electric cars.

The 12.8V/400Ah EG4-LL is just under 100 pounds. The Trojan SPRE 06-415s are a similar rated capacity (somewhat less in practice, but they're broadly close), and a pair of them to make a 12V system would be 236 pounds. So, slightly more than twice as much for a similar capability.
Sounds similar weight per Ah to mine. The delivery driver was moaning they gave him a bad back. I showed him no sympathy, especially when he kicked someone's Dyson box out of the way to get to them in the van. Maybe I should look back through camera footage and show it to his boss?
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Message 70754 - Posted: 6 Apr 2024, 7:06:33 UTC
Last modified: 6 Apr 2024, 7:12:38 UTC

I mean seriously, warnings on chainsaws not to stop them with your genitals?!
Where do you buy your chainsaws from? Neither of mine came with any such warnings!

And health and safety measures are only common sense for someone who fully understands what is involved. A chainsaw for example can under certain circumstances kick up which is why I always wear a safety helmet while using mine and modern ones all have a safety chain brake that will stop the chain by hitting against the top hand in such situations. Someone with no knowledge of chainsaws could buy one of the old fashioned ones and have no idea how dangerous it is. Health and safety warnings and measures are designed to protect those who don't understand what is involved.
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Message 70755 - Posted: 6 Apr 2024, 8:37:34 UTC - in response to Message 70754.  

I mean seriously, warnings on chainsaws not to stop them with your genitals?!
Where do you buy your chainsaws from? Neither of mine came with any such warnings!
https://www.forbes.com/2011/02/23/dumbest-warning-labels-entrepreneurs-sales-marketing-warning-labels_slide.html

And health and safety measures are only common sense for someone who fully understands what is involved. A chainsaw for example can under certain circumstances kick up which is why I always wear a safety helmet while using mine
How pathetic. I use two hands and it won't kick right up to my face. If it did, it would cut out before it got that far. And kicking up is damn obvious for anyone who understands the most basic law of physics, equal and opposite reactions. If you don't understand it, I don't want you to live. Imagine a world where all the stupid folk had been killed off.
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Message 70762 - Posted: 6 Apr 2024, 22:39:10 UTC - in response to Message 70751.  

They are more important than you?


Yes. Absolutely. Without question. I'd rather not kill them to save a few dollars on doing a job properly, especially when I'm saving so much by doing the work myself. I don't find "doing it properly" to be a particularly painful process, either. In the context of electrical wiring, this means NEC wire gauge or larger (I discovered that past-self was clever enough to use the full rated wire gauge for a run from my charge controller to my batteries, even though I had a smaller breaker in place at the time, meaning that when I needed to upgrade the breaker to better match my increased production, I didn't have to replace the wire run), proper junction bars as needed, etc. And I have a thermal imager to find hot spots - it's quite the fun little toy that gets used often enough to verify things are running as expected.

And we go overboard with safety. Obvious safety is common sense and doesn't need legislation.


The history of industrial accidents, aviation accidents, and quite a few other things disagrees. Quite a few things that matter to "not kill people" are not, in fact, "common sense" - or they'd have been done. Further, there's a difference (to my mind, at least...) between "doing something stupid that kills yourself" and "doing something stupid that kills other people." Electrical code falls into the second category - I'm familiar enough with the NEC (US electrical code) to recognize that it's exceedingly conservative, but it also does a pretty solid job of preventing the sort of penny pinching stupidity that burns down homes.

How pathetic. I use two hands and it won't kick right up to my face. If it did, it would cut out before it got that far. And kicking up is damn obvious for anyone who understands the most basic law of physics, equal and opposite reactions. If you don't understand it, I don't want you to live. Imagine a world where all the stupid folk had been killed off.


Man, you're an ass at times. I assume you do that on purpose. But it's far from the first time I've encountered that mentality.

I typically wear a helmet and hearing protection when using a chainsaw, and as I have a perfectly good set of chainsaw chaps, I wear those often enough too. I know people who've gone through 6-8 months of rather extensive pain, suffering, and loss of employment from having a circular saw go through their leg on the job. I'd rather avoid that experience, and it's a big reason I use a compound miter saw for most of my wood cutting as opposed to a circular saw. It's the same reason I wear competent motorcycle gear when riding. It's the difference between dying and surviving in pain, or the difference between surviving in pain and walking away from a crash while inventing a string of new cursewords. Been there, done that, am damned glad I had gear on when someone turned in front of me without anything like sufficient room for me to stop or get entirely out of the way.

Don't get me wrong. I fully support your right to use a chainsaw with zero protection at all. I fully support people riding motorcycles in shorts, a t-shirt, and flip flops. I just happen to think quite a few things like that are stupid. And I support my right to call people out for their overt stupidity.
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Message 70764 - Posted: 7 Apr 2024, 9:02:25 UTC - in response to Message 70762.  

They are more important than you?
Yes. Absolutely. Without question. I'd rather not kill them to save a few dollars on doing a job properly, especially when I'm saving so much by doing the work myself.
You're missing an important point, the chances of it killing them. There's no 100% safe and 100% dangerous, you have to decide how much risk you take.

I don't find "doing it properly" to be a particularly painful process, either.
Properly often means a lot more expense and time.

In the context of electrical wiring, this means NEC wire gauge or larger (I discovered that past-self was clever enough to use the full rated wire gauge for a run from my charge controller to my batteries, even though I had a smaller breaker in place at the time, meaning that when I needed to upgrade the breaker to better match my increased production, I didn't have to replace the wire run), proper junction bars as needed, etc. And I have a thermal imager to find hot spots - it's quite the fun little toy that gets used often enough to verify things are running as expected.
If you're dealing with low voltages, it's voltage drops which count, not overheating. And I do use decent thicknesses of cable for high voltages too, so the wire doesn't wear out. They tend to oxidise if they're warm all the time, then they end up not conducting at all.

And we go overboard with safety. Obvious safety is common sense and doesn't need legislation.
The history of industrial accidents, aviation accidents, and quite a few other things disagrees.
You're going with media hype. You hear of 100 accidents and are appalled, but you don't think of how many people didn't have the accident. It's the percentage which counts. Clearly 10 people dying out of 100 is not the same as 10 people dying out of a million.

Quite a few things that matter to "not kill people" are not, in fact, "common sense" - or they'd have been done.
No, it's just people taking risks. It's obvious what's dangerous and how dangerous it is.

Further, there's a difference (to my mind, at least...) between "doing something stupid that kills yourself" and "doing something stupid that kills other people."
Why? Why would you class yourself as less important than others?

How pathetic. I use two hands and it won't kick right up to my face. If it did, it would cut out before it got that far. And kicking up is damn obvious for anyone who understands the most basic law of physics, equal and opposite reactions. If you don't understand it, I don't want you to live. Imagine a world where all the stupid folk had been killed off.
Man, you're an ass at times. I assume you do that on purpose. But it's far from the first time I've encountered that mentality.
You like living in a world of idiots?

I typically wear a helmet and hearing protection
You must have sensitive ears. My mother does too, I was drilling through some tiles in her bathroom to put up a rail, and she actually said she felt dizzy from the noise. It didn't bother me at all, yet I have perfect hearing and she doesn't.

when using a chainsaw, and as I have a perfectly good set of chainsaw chaps, I wear those often enough too. I know people who've gone through 6-8 months of rather extensive pain, suffering, and loss of employment from having a circular saw go through their leg on the job.
And how many people do you know who have never had that happen?

It's the same reason I wear competent motorcycle gear when riding.
That I would do, because I think the chances of coming off are very high. So high in fact I'd never ride one. Motorcycling is probably more dangerous than using your saw without a helmet. In fact you admitted you've had an accident on one.

Don't get me wrong. I fully support your right to use a chainsaw with zero protection at all. I fully support people riding motorcycles in shorts, a t-shirt, and flip flops. I just happen to think quite a few things like that are stupid. And I support my right to call people out for their overt stupidity.
And I support their right to do it so they can be removed from the gene pool.
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Message 70766 - Posted: 8 Apr 2024, 14:14:33 UTC

Right. I'd forgotten your electrical knowledge was far enough off in the weeds that we can't actually have a reasonable discussion about what "shortcuts" are reasonable.
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Message 70767 - Posted: 8 Apr 2024, 14:47:19 UTC - in response to Message 70766.  

Right. I'd forgotten your electrical knowledge was far enough off in the weeds that we can't actually have a reasonable discussion about what "shortcuts" are reasonable.
Nothing I posted suggests that.
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Message 70768 - Posted: 8 Apr 2024, 22:36:01 UTC


And I do use decent thicknesses of cable for high voltages too, so the wire doesn't wear out. They tend to oxidise if they're warm all the time, then they end up not conducting at all.


How "warm" are you running your wires if they're oxidizing on you? And are you running improperly terminated aluminum? Copper doesn't do that at any sort of sane temperatures (I typically use 90C rated wire, though occasionally have to derate for 60C rated breakers/switches/etc).

(in the land of "Doing it properly," I've yet to use aluminum wire for anything, and never intend to - the slight extra cost for copper is totally worth the tradeoffs of "Isn't evil in screw terminals" like aluminum is)
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Message 70777 - Posted: 9 Apr 2024, 9:41:15 UTC - in response to Message 70768.  
Last modified: 9 Apr 2024, 9:42:24 UTC

And I do use decent thicknesses of cable for high voltages too, so the wire doesn't wear out. They tend to oxidise if they're warm all the time, then they end up not conducting at all.
How "warm" are you running your wires if they're oxidizing on you? And are you running improperly terminated aluminum? Copper doesn't do that at any sort of sane temperatures (I typically use 90C rated wire, though occasionally have to derate for 60C rated breakers/switches/etc).

(in the land of "Doing it properly," I've yet to use aluminum wire for anything, and never intend to - the slight extra cost for copper is totally worth the tradeoffs of "Isn't evil in screw terminals" like aluminum is)
GPU feeds, 12.6V, 4AWG ring. More the connections get hot. Also 5kW resistive house heating, whatever cables I had left over to interconnect thermostats etc. 8A cable, but single cores exposed to air. I paired them up but they still get hot. A lot more than body temperature is call I can say.

I do have CCA for the GPUs, but it's sold as overthickness by the same amount that aluminium conducts less. That's aluminium, not aluminum, maybe it's different electrically. The wire was about a third of the price and should conduct the same. I didn't bother working out what to get, I just add more where there's a problem. Too complicated to calculate, depends where I clip on GPUs and PSUs.

Dunno what you mean by evil screw in terminals.
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Message 70779 - Posted: 9 Apr 2024, 11:58:42 UTC - in response to Message 70777.  

Peter. Do some quick sums to check the rating of the cable needed for you 5kw resistive heaters. Even doubled "8A" cable is way under sized:
5000/240 = 20.83A (assuming you actually getting 240v in your location) - so you need to at least use three cables, single in air; but even that is marginal if the mains voltage droops to say 220v (which is still within spec of UK supply).

Oxidation of conductors is more often associated with environmental conditions than temperature of conductor (unless the conductor is REALLY hot - over say 200C). The most common to fail first at elevated temperatures is the insulation. The mode of failure depends on the insulation material and the conductor metal will delaminate from the conductor, or go "brown and crispy", or go soft and floppy.

Evil screw connectors - aluminium (miss-spelled by those led by the Americans for spelling as aluminum) conductors take very badly to being compressed by most screw terminals rapidly becoming work-hardened and so fracture. (Yet another good reason for not using aluminium conductors in domestic installations.)
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Message 70780 - Posted: 9 Apr 2024, 12:29:05 UTC - in response to Message 70779.  
Last modified: 9 Apr 2024, 12:40:03 UTC

Peter. Do some quick sums to check the rating of the cable needed for you 5kw resistive heaters. Even doubled "8A" cable is way under sized:
5000/240 = 20.83A (assuming you actually getting 240v in your location) - so you need to at least use three cables, single in air;
They're rated at 8A when in a 3 core sheath. Out of that sheath I expected them to handle 10A each. But what I think I'm coming up against is the trend nowadays for things not to do what they say on the tin. Disks are measured in billions of bytes, not real gigabytes. Cameras claiming 50MP only give you about a quarter of that, very easy to check. Paint which claims it needs one coat actually needs two.

but even that is marginal if the mains voltage droops to say 220v (which is still within spec of UK supply).
Actually resistive heating conducts less current as the voltage drops.

Interesting point, most people think it's been equalised with the EU, it hasn't, we're still 240 and they're still 220, which messes up some guitar amps. But most things are sold as 230V+/-10%.

Oxidation of conductors is more often associated with environmental conditions than temperature of conductor (unless the conductor is REALLY hot - over say 200C). The most common to fail first at elevated temperatures is the insulation. The mode of failure depends on the insulation material and the conductor metal will delaminate from the conductor, or go "brown and crispy", or go soft and floppy.
They weren't hot enough to melt the insulation, I've seen that in more extreme cases. They were comfortable to hold, but I could tell they were warmer than me. I'd guess 60-70C.

Evil screw connectors - aluminium (miss-spelled by those led by the Americans for spelling as aluminum) conductors take very badly to being compressed by most screw terminals rapidly becoming work-hardened and so fracture. (Yet another good reason for not using aluminium conductors in domestic installations.)
Ah, a BT engineer told me this was why my 1979 phone line was rubbish. He said something about them coming loose. But for the price I'll stick to aluminium!
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Message 70781 - Posted: 9 Apr 2024, 16:31:25 UTC - in response to Message 70780.  

Ah, a BT engineer told me this was why my 1979 phone line was rubbish. He said something about them coming loose. But for the price I'll stick to aluminium!


See Terry Pratchett.

The reason that the rich were so rich, Vimes reasoned, was because they managed to spend less money,” wrote Pratchett. “Take boots, for example. He earned thirty-eight dollars a month plus allowances. A really good pair of leather boots cost fifty dollars. But an affordable pair of boots, which were sort of okay for a season or two and then leaked like hell when the cardboard gave out, cost about ten dollars. Those were the kind of boots Vimes always bought, and wore until the soles were so thin that he could tell where he was in Ankh-Morpork on a foggy night by the feel of the cobbles. But the thing was that good boots lasted for years and years. A man who could afford fifty dollars had a pair of boots that’d still be keeping his feet dry in ten years’ time, while a poor man who could only afford cheap boots would have spent a hundred dollars on boots in the same time and would still have wet feet.
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Message 70784 - Posted: 9 Apr 2024, 19:12:05 UTC - in response to Message 70781.  

Ah, a BT engineer told me this was why my 1979 phone line was rubbish. He said something about them coming loose. But for the price I'll stick to aluminium!
See Terry Pratchett.

The reason that the rich were so rich, Vimes reasoned, was because they managed to spend less money,” wrote Pratchett. “Take boots, for example. He earned thirty-eight dollars a month plus allowances. A really good pair of leather boots cost fifty dollars. But an affordable pair of boots, which were sort of okay for a season or two and then leaked like hell when the cardboard gave out, cost about ten dollars. Those were the kind of boots Vimes always bought, and wore until the soles were so thin that he could tell where he was in Ankh-Morpork on a foggy night by the feel of the cobbles. But the thing was that good boots lasted for years and years. A man who could afford fifty dollars had a pair of boots that’d still be keeping his feet dry in ten years’ time, while a poor man who could only afford cheap boots would have spent a hundred dollars on boots in the same time and would still have wet feet.
Not necessarily true. Sometimes the cheaper thing is better value. It might cost 5 times as much for a better tool/battery/whatever which lasts twice as long. So just buy two of the cheap ones.

And in the case of aluminium wire coming loose, it only wastes two minutes of your time tightening it.
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Message 70785 - Posted: 9 Apr 2024, 19:32:13 UTC - in response to Message 70777.  

GPU feeds, 12.6V, 4AWG ring. More the connections get hot.


The connections shouldn't be getting that hot - usually that indicates a poor crimp job, though if you're using aluminum wire (aluminium, however you want to spell it, same material - Al, of some reasonable alloy), you've likely got some oxidation issues going on at the connection. Oxidized copper conducts. Oxidized aluminum doesn't, and a high resistance connection makes for a lot of heat, and tends to make the oxidation issues worse until something stops working - or, more often than it ought, catches fire (I've seen research that the number of "thermally faulty" outlets in a fleet of houses with aluminum wiring vs copper is about 50x higher for aluminum - and that's before you get into the long term behavior of the wire, which is "less agreeable" in terms of work hardening, thermal hardening, etc).

There are reasonable places to use aluminum wire, but I'd argue (as a serious DIY sort) that aluminum wiring is best left to people doing it professionally, because it really helps to have things like explosively welded lugs on the end of large gauge aluminum wiring (they literally weld the lugs to the wire with explosives, and there's no way for it to oxidize at the joint as the metals are firmly bonded). If you try to treat it like copper wire, you'll have a genuinely bad time of it eventually, because it's not well behaved like copper is - it work hardens more easily, it's more prone to stress fractures and cracks, and you pretty much can't use it in screw terminals for the long term, because the thermal expansion and oxidation behavior will eventually make your screw terminals glow with any serious power through them.

Wire is such a small part of any of my project costs that it's not worth the savings, over using something well behaved (copper). Though even there, I've learned about the problems with fine stranded cable - you can't use it in screw lugs, as it'll "flow" over time away from the screw, so you have to put a bootlace ferule on it first (or some sort of crimped terminal). Or just use regular stranded cable and skip the fine stranded for interconnects. I've got a range of good crimping tools, to include a DC wire crimper that will do up through 0000AWG or maybe a bit larger.


Also 5kW resistive house heating, whatever cables I had left over to interconnect thermostats etc. 8A cable, but single cores exposed to air. I paired them up but they still get hot. A lot more than body temperature is call I can say.


Wiring up high loads with "cables laying around," where you don't know the wire gauge, haven't calculated loads, etc, is the sort of "casually sloppy with high power things" I'm criticizing you for, in the sense of claiming that you don't have enough electrical background to be able to have any interesting conversations about your shortcuts. At least in your posts here, you come across as having a "Eh, whatever, it works for now..." attitude towards wiring.

Your wiring should (if it's halfway competent wiring) be labeled with wire gauge, either in AWG, or in cross sectional area, and it should also be labeled with the insulation temperature rating. The lowest temperature wiring insulation in common use is 60C/140F rated, and I would be quite uncomfortable with that running as hot as you describe. As I said previously, I generally use 90C rated wire, though I also don't run it near the thermal limits as I like the headroom.


The wire was about a third of the price and should conduct the same. I didn't bother working out what to get, I just add more where there's a problem. Too complicated to calculate, depends where I clip on GPUs and PSUs.


Is it actually conducting the same, with your particular terminals? "Adding more when there's a problem" isn't a replacement for a properly designed system, as by the time you notice it's hot, you've likely already gotten things hot enough to start causing thermal damage and further oxidation. A hunk of wire can heatsink a lot of heat, but it's not infinite.

They're rated at 8A when in a 3 core sheath. Out of that sheath I expected them to handle 10A each.


8A continuous, or intermittent? Typically, in electrical rating for wiring, there's a different rating for "continuous" (>3 hour) loads vs intermittent loads, and at least in the US National Electric Code, an 80% derating applies for continuous loads. So 90C 12AWG is rated for 30A, but for continuous loads, it's only suitable to 24A. This handles thermal mass and inertia in wiring - running a blender for 5 minutes is going to heat up wiring less than a heater, solar backfeed, EV charger, hot tub heater, etc.

This is why wire also generally isn't rated for "amps" - it's given in wire gauge and temperature rating of the insulation, and then you apply the standard math formulas (handily provided in table form in the NEC) to figure out what they can carry, or what you need for a given current - though you typically up with some standard answers, and if you end up with something radically divergent from what's expected, check your math. My solar install runs from the panels to the inverters are 12AWG for about 10A peak current, because of derating for temperature and number of wires in the conduit, among other things.

But what I think I'm coming up against is the trend nowadays for things not to do what they say on the tin.


What gauge is your wiring? I'm guessing 18AWG 60C or smaller? The US NEC at least doesn't go that small...

But for the price I'll stick to aluminium!


Given that you don't seem to know anything about the particular quirks and hazards of Al wiring, that doesn't seem wise to me. It absolutely is not the same to deal with as copper wiring.

But at least there's an ocean between your place and mine.
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Message 70786 - Posted: 9 Apr 2024, 19:37:47 UTC - in response to Message 70784.  

And in the case of aluminium wire coming loose, it only wastes two minutes of your time tightening it.


"Ah, just tighten it up again!" is literally the path to one of the more common failures of aluminum wiring in service.

Aluminum has a far higher coefficient of thermal expansion than copper, and is prone to "creep" (where it will continue to flow for some while after being tightened, so end up loose again if you over-torque the connector.

I'd suggest using a torque wrench, but I'm guessing that's "too expensive" and "too complicated" for your preferences in wiring.
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