to fill the battery of a phone or device with power
My phone's nearly dead, I need to charge it up.
Make sure you charge up the laptop before the trip.
I charged up my phone overnight. (refilled the battery) They charged me for delivery. (asked for money)
Common mistake
✗My phone's dead — I need to charge up it.
✓My phone's dead — I need to charge it up.
With a pronoun, split the verb: 'charge it up'.
Tell it apart
I charged up my phone overnight.
refilled the battery
They charged me for delivery.
asked for money
The 'up' is optional — 'charge my phone' works too — but very common in speech.'Charge up' is about refilling a battery; plain 'charge' can also mean to ask someone for money.
To charge up a device is to plug it in and fill its battery with power.
I'll just charge up my phone before we head out — it's nearly dead.
Have you charged up the speaker? We'll need it for tonight.
Charge it up overnight. (fill the battery) The battery ran down by noon. (drained to empty)
Common mistake
✗I need to load up my phone.
✓I need to charge up my phone.
Batteries 'charge up', not 'load up' — 'load' is a false friend here.
Tell it apart
Charge it up overnight.
fill the battery
The battery ran down by noon.
drained to empty
The 'up' adds the sense of filling it to full. 'Charge it' on its own is also fine.'Charge up' fills a battery; the opposite is 'run down' or 'die' (drain to empty).