The other day I was chatting to someone about my Jackery Solar Generator setup, and the subject got onto how much money you can save.
"I bet you could save a lot of money using that to charge up your iPhone!"
I'd never thought about it, so I decided to run the numbers.
The iPhone I'm using is an iPhone 11 Pro Max, and its battery has a capacity of 15.04 watt-hour.
Now let's assume some assumptions. First, the battery has a lifespan of 500 recharge cycles, which means that over that time, it has slurped in 7,500 wh (watt-hours of power), or 7.5 kwh (kilowatt-hours) of power.
Let's now assume that the charging system is 90% efficient, which means that the battery has taken in about 8.3 kwh of power.
In the US, the average cost of 1 kwh of power is about 12 cents, so over its entire lifespan, that iPhone has cost a dollar.
Let's do the same for a MacBook Pro. The latest M1 13-inch MacBook Pro has a 58.2 wh battery and is good for 1,000 recharge cycles.
Again, assuming 90% efficiency in charging, and that power is the average 12 cents, that MacBook Pro will cost (assuming it's running purely on battery power) under $8 to run.
Let's also put this in the context of the average US residential utility customer, who uses about 900 kwh of power per month.