111–120 of 141 posts
The authors "92%" efficiency calculations will be with the inverter and power supply at high load. When drawing only 20 watts, I expect you'll see more like 80% efficiency, and maybe as low as 50%.
Earlier quoted context omitted.
Basically this: https://voltaicsystems.com/arc20w-kit/ . It's a bit on the expensive side, I'm sure you can find cheaper kits. I like that the battery has a USB-C port, so I can charge the MacBook directly. To be truly off-grid, you need something bigger though. 20W is ok for basic work, but if you're compiling or doing other heavy work you need more power. If it's a bit cloudy then the battery won't fully charge wit…
Nekteck sells a car charger with 45W USB-C PD. I've seen others claiming 65W. https://www.nytimes.com/wirecutter/reviews/best-usb-car-char...
This is an aburdly bad result, mostly caused by the questionable 14W base power draw, but also due to the questionable choice of gzip compression, which is not exactly on the frontier of compression technology. Even zlib-deflate would decompress twice as fast at the same size ratios, but something like lz4 or snappy would be an order of magnitude less CPU time cost for similar compressed size. The real way to have an…
If I could find a way to encourage people to run their work in a power efficient way using economies of scale from this series, I would be terribly happy.
Interestingly I suspect public-cloud FaaS solutions (e.g. AWS Lambda) will achieve highest utilisation rates due to high rate of CPU sharing - but I’m a long way off from showing that with data.
The authors "92%" efficiency calculations will be with the inverter and power supply at high load. When drawing only 20 watts, I expect you'll see more like 80% efficiency, and maybe as low as 50%.
I’ll try to measure this. I guess I need to purchase a shunt.
For the AC side, it's much harder to measure - typical inverters have rather imperfect AC outputs, and unless you have a rather expensive multimeter you won't get an accurate power measurement. A kill-o-watt will probably be okay for a rough measurement, but there might well be a +- 20% error...
Earlier quoted context omitted.
> run on intel only How does that work on a Ryzen laptop?
The English doesn't (quite work), but Intel here refers to the integrated, power-thrifty GPU, so could be more pedantically stated as "run on integrated graphics chip and turn off the Nvidia discrete GPU (and save power)" instead.
Earlier quoted context omitted.
You could also use a desktop with one of these ATX power supplies that runs on 12VDC instead of 120/240VAC: https://www.cartft.com/catalog/il/2302
Wow, I was not expecting that price! Is this just a rare item or is there something particularity expensive inside it?
How much trouble shooting does it eliminate?
How much experience does it make unnecessary?
Or to put it another way, at the point where 1500w of 12v source computer power supply makes sense, the price is not unreasonable.
I regularly work outside during summer, powering a MacBook Pro exclusively by sunlight (panel about 1m^2). For a few hours I can get a good 50+ watts, buffering thru a 100Wh battery. Keeping the load typically around 10-15 watts isn't hard, so long as paying attention. Of note, I persuaded Atlassian to remove the (rather nice) animated clouds from their "you have been logged out" web page because it pulled 30 watts (…
Also, how are you measuring a 10-15W load? When plugged in, the charger is going to pull it's rated load from your battery bank (I'm seeing ~84W including inverter losses).
What about router/modem power draw? Needs to be some sort of connection to the internet to truly function as a website. (Not being connected would mean it's a wan site or intranet site)
> 12v to 240v inverter Can someone explain this part of his equation? What’s he doing with 240v? Or maybe he meant 24v for charging the laptop?
He's using a household solar inverter designed to convert low voltage DC to AC at standard wall socket voltage. It's not the most efficient approach, as noted in other comments, but it's an easy approach since these inverters are common and a laptop's power supply is already set up to plug into a wall socket.
I regularly work outside during summer, powering a MacBook Pro exclusively by sunlight (panel about 1m^2). For a few hours I can get a good 50+ watts, buffering thru a 100Wh battery. Keeping the load typically around 10-15 watts isn't hard, so long as paying attention. Of note, I persuaded Atlassian to remove the (rather nice) animated clouds from their "you have been logged out" web page because it pulled 30 watts (…
50W seems rather low for a a 1m^2 panel. I have some older 250W panels (1.6m^2) and get around 220W in the summer. Also, how are you measuring a 10-15W load? When plugged in, the charger is going to pull it's rated load from your battery bank (I'm seeing ~84W including inverter losses).
Battery (Goal Zero Sherpa 100AC) shows output load. Lowest draw on MacBook Pro 15" is 7W, usually idling 10-15W, pulls about 50W when charging.