3 ms·

> For context, 1.6 kW is about enough to power 1 home appliance: a dishwasher, refrigerator, or toaster. Most (US) homes put outlets on a 15A breaker (sometime

> For context, 1.6 kW is about enough to power 1 home appliance: a dishwasher, refrigerator, or toaster. Most (US) homes put outlets on a 15A breaker (sometimes 20A), which gives have 1.8 kW to play with. So this is less power than a typical home outlet. > I think your A/C would be more - but I'm not certain A/C definitely requires far more power—you have to deal a high peak load for motor start. Absolutely not happening with this setup. The applications of this are rather curious, and definitely not for the any typical person. Probably defense, with a very short lead time, with the need for faster mobility? > If you had Solar panels deliver this power [...] Yes, definitely. And it can still be highly mobile: https://www.youtube.com/watch?v=VTiDklyEYaI https://www.youtube.com/watch?v=VTiDklyEYaI (and once a setup is at a location, you could throw it on the back of a truck for some short-range transit. You'd just need to spread out the solar in each new place. FWIW, Solar and Microwave both have interesting yet different line of sight requirements.)

skykooler 5y ago
My window-mount AC unit says to put it on a dedicated 15A circuit, which should mean it pulls a maximum of 1.8 kW, no? Otherwise it would trip the breaker every time it turned on.
- invalidator 5y ago
  Most breakers do not trip instantly. They are designed to protect the wiring insulation from melting. Because the wires have thermal mass, a brief pulse above rated power is fine. Your 15A A/C may pull 30A or even 45A for 100ms while starting, and that's okay because the wiring won't overheat that quickly. It does drag down the voltage on the wiring though, which is why some lights may flicker when it starts.
  - kube-system 5y ago
    Residential breakers (in the US at least) have two trip modes -- a delayed trip thermal mechanism, and a fast trip magnetic mechanism. What it essentially does is trip faster if you overload it more. There are requirements for how long a breaker can take to trip at 135% of the rating, and a faster trip time required at 200% of the rating. I think some people have probably experienced this first hand -- if you just barely overload a breaker, it might take a little while for it to break, and if you turn it back on, it might stay on a little bit before breaking again. And if you really overload it or short it out, it'll break right away. This is all by design.
yencabulator 4y ago
> A/C definitely requires far more power—you have to deal a high peak load for motor start. Absolutely not happening with this setup. It depends on what size A/C we're talking about. After all, window units run off a regular 15A wall plug. I've also run an RV A/C unit manufactured around 2006 at about 13 amps continuous draw during duty cycle, insignificant surge at startup, with a 3 kW inverter (plenty of capacity left over) and LiFePO4 batteries. Make that A/C 10+ years newer and it would draw a a few amps less, too. And if the surge is too much, there's an extra gadget you can install in the A/C that's essentially a capacitor for smoothing the surge.
varenc 5y ago
> Most (US) homes put outlets on a 15A breaker (sometimes 20A), which gives have 1.8 kW to play with. So this is less power than a typical home outlet. US outlets run at 15A, but per the NEC [0] no single plug-in appliance can continuously pull more than 80% of the max rating, or 12A. Which is why space heaters all max out at 1500W instead of 1800W. But an intermittent appliance, like a hair dryer or toaster, can pull the full 1800W though. NEC 210-23: https://arlweb.msha.gov/District/DIST_09/Electrical%20test%20materials/ART210.pdf https://arlweb.msha.gov/District/DIST_09/Electrical%20test%2...

skykooler 5y ago

My window-mount AC unit says to put it on a dedicated 15A circuit, which should mean it pulls a maximum of 1.8 kW, no? Otherwise it would trip the breaker every time it turned on.

invalidator 5y ago
Most breakers do not trip instantly. They are designed to protect the wiring insulation from melting. Because the wires have thermal mass, a brief pulse above rated power is fine. Your 15A A/C may pull 30A or even 45A for 100ms while starting, and that's okay because the wiring won't overheat that quickly. It does drag down the voltage on the wiring though, which is why some lights may flicker when it starts.
- kube-system 5y ago
  Residential breakers (in the US at least) have two trip modes -- a delayed trip thermal mechanism, and a fast trip magnetic mechanism. What it essentially does is trip faster if you overload it more. There are requirements for how long a breaker can take to trip at 135% of the rating, and a faster trip time required at 200% of the rating. I think some people have probably experienced this first hand -- if you just barely overload a breaker, it might take a little while for it to break, and if you turn it back on, it might stay on a little bit before breaking again. And if you really overload it or short it out, it'll break right away. This is all by design.

yencabulator 4y ago

> A/C definitely requires far more power—you have to deal a high peak load for motor start. Absolutely not happening with this setup. It depends on what size A/C we're talking about. After all, window units run off a regular 15A wall plug. I've also run an RV A/C unit manufactured around 2006 at about 13 amps continuous draw during duty cycle, insignificant surge at startup, with a 3 kW inverter (plenty of capacity left over) and LiFePO4 batteries. Make that A/C 10+ years newer and it would draw a a few amps less, too. And if the surge is too much, there's an extra gadget you can install in the A/C that's essentially a capacitor for smoothing the surge.

varenc 5y ago

> Most (US) homes put outlets on a 15A breaker (sometimes 20A), which gives have 1.8 kW to play with. So this is less power than a typical home outlet. US outlets run at 15A, but per the NEC [0] no single plug-in appliance can continuously pull more than 80% of the max rating, or 12A. Which is why space heaters all max out at 1500W instead of 1800W. But an intermittent appliance, like a hair dryer or toaster, can pull the full 1800W though. NEC 210-23: https://arlweb.msha.gov/District/DIST_09/Electrical%20test%20materials/ART210.pdf https://arlweb.msha.gov/District/DIST_09/Electrical%20test%2...