Pls help me to explain this sentence?

Question

I am not native English. Pls help me to explain this sentence or more is better. Many thanks
How to understand this sentence?

- “Power cubes are 60-80 percent inefficient” 
is it means when battery is full, if we still plug into power strip, there is only 60-80% still in not using… But we waste remain 20-40% energy.
In whole paragraph:

Plug anything that can be powered by a remote control or that has a power cube transformer (little black box) into a power strip, and turn it off, and/or unplug, when not in use. (Power cubes are 60-80 percent inefficient.)

Tk you very much

l_pro · Accepted Answer

This means power cubes are 60 to 80% less inefficient. So they are only 20 to 40% of their use is deemed efficient.

Power cubes basically use more power than alternative transformers when not in use and plugged in.

YoYokiller · Answer

Well if it says inefficient then 60-80 of whatever it uses is a wasted.

Anonymous · Answer

yes, you are right, bit sketchy though but your getting there

Pls help me to explain this sentence?

3 Answers