Can You Charge a Power Bank with Another Power Bank?

So you’re wondering if you can charge a power bank with another power bank and if it’s safe to do so.

Maybe your friends brought their own power banks but forgot to charge them. The solution here is very simple but there are a couple of pointers to keep in mind.

Let’s take a look.

Can You Charge a Power Bank with Another Power Bank?

a white power bank with multiple ports

Yes. It is safe to charge a power bank with another power bank but it’s not very efficient. With power banks that have a single USB-C port, the power bank with the higher battery capacity will usually deliver the power.

If you have a power bank that is fully charged, you can use it to charge another power bank. You can even use one power bank to charge multiple power banks at the same time.

Further reading: Did you know a power bank can charge a laptop? 

How to Charge a Power Bank with Another Power Bank

  • Locate the output port on the power bank you know has power.
  • Plug the other end into the charging port of the power bank you want to charge.
  • A blinking light should indicate that the power bank is being charged.

Most power banks have multiple ports labelled for input or output. The input is used for charging the power bank, and the output is used for charging external devices.

Power Banks with a Single USB-C Port

However, there are some power banks that have a single USB-C port that is used for both input and output.

In this case, the power bank that has more battery capacity will charge the other.

Bear in mind, we’re not referring to the maximum charge capacity rated in mah, but rather the actual total charge stored inside the battery.

In other words, a 5,000 mah power bank can charge a 10,000 mah one, but only if it has more total charge than the other.

The 10,000 mah power bank would have to be basically completely drained.

Thankfully, you don’t need to worry about running into this situation that often because the vast majority of power banks have ports for in and out.

If you’re looking for a good power bank to buy, I highly recommend Anker Power Core Essential 20K 20,000 mAh power bank.


Not Efficient

On the other hand, charging a power bank with another one is not very efficient. Don’t expect an exact 1:1 transfer.

It’s not nearly as efficient as charging from a supported charger; a lot of energy will be lost in the process.

Slow Charge Speed

The charge speed will also be rather slow, depending on the energy output, and whether the empty power bank supports a fast charge technology.

Wrapping It Up

So don’t worry about charging a power bank with a different power bank, it’s perfectly safe.

However, it can get a little tricky when you’re trying to charge two power banks that only have one input port.

Overall, it’s better to remember to charge your power banks beforehand, so you have more total stored energy in case of emergencies.


  • Timothy Gagnon is the owner of My Portable Office. As a kid, he's always had a fascination with electronics and never passed on the chance to disassemble and reassemble them. When he's not taking a hammer to his electronics, he can be found playing with his cats or writing about his latest discoveries on My Portable Office.