In theory, it should be "recharge" my phone, but you will hear people say "charge" my phone. To a native ear there is no difference. Colloquial speech is far too common in everyday speech.

Great question! In everyday English, “charge” and “recharge” can often be used interchangeably when talking about adding energy to a device like a phone. However, there is a slight nuance: • “Charge” is the more common and general term. It simply means to supply electrical energy to a device. • Example: I need to charge my phone. (This is what most native speakers would say.) • “Recharge” technically means to charge something again, implying that it has been charged before and has now run out of energy. • Example: I need to recharge my phone. (This is correct, but “charge” is more natural in casual speech.) In your example, both sentences are understandable and correct, but “I need to charge my phone” is what most people would say. “Recharge” is sometimes used for emphasis, especially in contexts like batteries, prepaid cards, or personal energy (e.g., “I need to recharge my batteries” meaning “I need to rest”). So, while there’s a minor difference, in your context, they essentially mean the same thing. ----- On the other hand ------ When talking about a person, “recharge” is often used metaphorically to mean rest and regain energy. • Example: I need to recharge after a long day at work. • Example: This weekend is all about recharging my batteries. It suggests taking a break to restore physical, mental, or emotional energy.

Technically they're different. But since a phone needs to be charged many times, they're basically the same thing in this case. The only time you couldn't use 'recharge' would be they very first time you charged it.