Given an on-the-grid, non-solar house, is it more energy efficient to charge your phone in your house or in your car? If there would be a difference for gas-powered and electric vehicles, please explain that as well.
In: Technology
Internal combustion is a pretty inefficient way of generating/capturing energy. It uses little explosions that cause pistons to move, and much of the energy generated by those explosions becomes waste heat. Even if you’re comparing that to a powerplant that also fundamentally operates by burning a fossil fuel, the powerplant will be more efficient because it gets to be big, specialized, and stationary. The alternators that convert some of the car’s energy into electricity are likewise less efficient than the generators used in powerplants.
Realistically, a phone battery is so small that it’s going to have a near-zero impact on power usage.
The newest iPhone battery draws 0.008 kwh per day assuming average 85% charge daily.
That’s a monthly total power usage of 0.24 kwh, at an average cost of $0.04 monthly.
i’d say house. it takes the same amount of power to charge your phone regardless. if your car is running, obviously you are just wasting energy while your phone charges. if it isn’t running, youre just trading the energy in your car battery to your phone. replacing that energy eventually requires starting your car which in this scenario is the least efficient thing. or if you have an EV hooking it up to the grid anyway.
If you are going to be using the car anyway, charging up while driving place to place will be an insignificant impact on your fuel mileage, so in a way, you could consider it a ‘free’ charge up. If you are running your car just to charge the phone, well, that is going to be horribly wasteful and inefficient…
A car engine has a thermal efficiency of somewhere in the region of 25%. A coal fired power station is about 40% and a gas fired power station about 60%. Most power grids in the developed world have a significant contribution from one or more of wind, solar, hydro or nuclear, which are all carbon emissions free. So the grid is going to be significantly less polluting in almost all cases than a car. For an electric car, the conversion of grid to car battery to phone charger will make it less efficient than charging the phone directly from whatever power source charged the car.
in your house. small engines are less effcient and charging an EV just to charge your phone adds the battery inefficiency when you didnt need to.
If you’re already using the car, gas or electric, using the car would he better because you’re already spending that energy.
In any other case, you should use your home. Even if the home is being powered by a gas generator, because that gets you more kWh per gallon than the car would, but the car is designed to move you, not power you.
Also, if you’re off grid and only using combustion for energy, you should really reconsider your options. Solar and wind are basically free once you pay the one time costs.
Usually the house, because introducing another battery in the middle is inefficient as some energy will be lost to heat and battery degradation. However, it is common for electric car owners to sign up to an electricity contract where power is cheaper at night, and the car will usually be set to do its regular charge on cheap power. So if you wanted to charge your phone at a peak time it might be cheaper to go and take power from the car battery.
In practice the amount of energy is so small it makes no difference to anything.
Is this question specifically in regard to charging phones? Or is it a bigger question of “is my home electric more efficient than the electric from my car”
If it’s the first one… It doesn’t matter. None of it does. Phones use so little power relatively speaking that there is no efficiency gains or losses by using different sources.
if it’s the second one… Home energy is generally more efficient, unless you want to look into power footprint of that energy up the path to the power station and how that energy is generated, but also something you have little control over.
If you charge the car off the house, and then the phone off the car, you could bring the phone in and charge the house – so then it’s basically free
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