Is it more energy efficient to charge a phone/tablet using a desktop/laptop while your computer is being used vs using the charger?
Is it more energy efficient to charge a phone/tablet using a desktop/laptop while your computer is being used vs using the charger?
I was just thinking if you are on your computer anyway would it just use some of the excess electricity that your computer would have wasted or would it be worse than charging your phone from a charger while using your laptop separately.
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There is no such thing as 'excess electricity' in a modern (switching) power supply unit. They use as much power as is needed. There is a few percent of loss in the device, no big deal.
Some desktop computers are less efficient because they have too strong psu's (lots of reserve for your future "gaming" graphics card) built in.
This would only affect the 12V rail though no? It's not like they are beefing up the 5V rail that supplies your USB ports in excessive amounts. Picking a random PSU from pcpartpicker, the CORSAIR RM650e vs RM1200e (650W vs 1200W) both have a +5V@20A rail. There would be no need to have a larger 5V rail to support gaming cards.
Also correct me if I am wrong, most PSU's are more efficient at 20-50% utilization, not 100%. I'm basing this off the higher ratings for 80 Plus.
I've previously spoken with PSU engineers for enterprise power supplies -- specifically for 48-54v PoE equipment -- who described to me that today's switch mode power supplies (SMPS) tend to get more efficient with increasing load. The exception would be when the efficiency gains from higher loading start to become offset by the heating losses from higher input currents.
This graph for a TDK PSU shows that North American 120 VAC nominal (see here for the small difference between nominal and utilization voltages) will cause a small efficiency hit above 75% or so. And this is exactly why data centers -- even in North America -- will run with "high line" voltage, which is 200 VAC or higher (eg North American 208VAC delta supplies, British 240/415 wye, European 230/400 wye).
I guess being on a laptop I don't have to worry about the PSU being less efficient.