Can I leave my charger plugged in?

You should keep it plugged in until you need to use it. You can even leave it plugged in while using it. Yes, there is a positive benefit to leaving it plugged in.

Here’s the long answer→When to charge your iPhone or iPad | Communities

Yes, and the things that use energy when it is fully charged will use energy from the charger rather than the battery, thus reducing the number of battery-killing charge cycles over the long haul.

Yes.

Tiny power use although the planet is probably weeping,

And charge the phone every night all night.

I noticed that the moment my iPhone is done charging, my MagSafe charger is cool to the touch!

Does that mean that it trickle-charges (as needed)?

mr fish Said:

"I noticed that the moment my iPhone is done charging, my MagSafe charger is cool to the touch! Does that mean that it trickle-charges (as needed)?"

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Sure. Sounds cool to me.

Wait, what?

Are you suggesting that keeping it plugged in is a benefit?

I typically remove it from the charger when I wake up in the morning.

Pepina11 Said:

"Can I leave my charger plugged in?"

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Avoid Overheating:

As long as you have a need to change something, leaving it in is what to do. Elsewise, it may overheat (or you might trip on the cord), which is something to avoid altogether.