How long does 20000mah power bank last? (Expert Analysis)

When it comes to buying the best power bank that will last for long time in a given day, there’s no doubt that 20000mah power bank is among the list.

Now you want to know how long does 20000mah power bank last, first I must tell you 20000mah power bank can last for a while given day but it depends on your phone battery capacity.

Before buying a new power bank for your mobile phone, there are certain things that you should consider and the first and foremost is your mobile phone.

You should ask yourself this question of

  • How big or small is my phone battery capacity
  • Is the power bank too small or big for my phone battery capacity
  • How good is the power bank
  • Will the power bank last for a good number of years
  • Is the power bank compatible with my mobile phone

These are the necessary questions you need yourself before going ahead to buy a new power bank for your mobile phone.

Talking about 20000mah power bank, no one will doubt that it is a very large capacity power bank and I happen to have two different brands from the best companies that produces power banks or portable chargers.

To properly answer the question of how long does 20000mah power bank last, I will explain it based on my experience with my Romoss 20000mah power bank and anker 20000mah power bank.

Let’s continue.

How long does 20000mah power bank last?

A 20000mAh power bank can last for 24hrs though it depends on the user’s phone battery capacity. The lower the phone battery capacity, the more a 20000mAh power bank will last longer for you. 

Having said that I owned two 20000mah power bank along with samsung galaxy s21 ultra which has a 5000mah battery capacity, Samsung Galaxy s9 plus with 3500mah batter capacity, and iPhone xs max with a battery capacity of 3174mAh.

Now this is my experience.

1. Romoss 20000mah Power Bank 

how long does 20000mah power bank last

This is my very best power bank, the romoss 20000mah power bank and there are different models in the market.

Experience charging samsung galaxy s21 ultra using Romoss power bank: Samsung galaxy s21 ultra has a large battery capacity of 5000mah and the battery life is very suberb i must admit. Using my romoss 20000mah power bank to charge samsung galaxy s21 ultra will only go for two and half charges and the romoss power bank was dead flat.

This is very good because most power banks i used only charged the galaxy s21 ultra and boom the went dead flat, but romoss 20000mah power bank charged the phone for a good two time and half before going flat.

Experience charging samsung galaxy s9 plus using Romoss power bank: Using romoss 20000mah power bank to charge the old Samsung Galaxy s9 plus was a sweet one as the power bank charged the galaxy s9 plus for a good three times before going flat.

I used the romoss power bank to charge my galaxy s9 plus from 15% to 100% for good three times and I really surprised because I never expected it to charge the phone fully for three times.

I used the romoss to charge the galaxy s21 ultra from 25% to 100% for two times as the third one only went from 25% to 48%.

Experience charging iphone xs max using Romoss power bank: As the iphone xs max has a good battery life and capacity of 3174mAh, the romoss 20000mah power bank charged the iPhone xs max  twice fully, with the third charge going from 20% to 72%.

This shows you how good the romoss power bank is.

You can even use the romoss 20000mah power bank to charge iphone 11 or iphone 12 for a good three times based on my observation.


You can buy the original Romoss power bank from Amazon.


2. Anker 20000mah Power bank

how long does 20000mah power bank last

Another good quality 20000mah power bank i will use to explain to you how long does 20000mah power bank last is the anker power bank.

Anker is one of the best power bank or i will say the bear though some will argue with me. When talking about the 20000mah power bank and you didn’t mention any of the anker power bank, then the list is probably not complete.

Experience charging samsung galaxy s21 ultra using anker power bank: Using the anker 20000mah power bank was able to charge my samsung galaxy s21 ultra for almost three times before going dead flat. Romoss 20000mah power bank was able to charge the phone fully for a good two times as the third charge went from 25% to 48%.

However, the case was different using anker 20000mah power bank to charge samsung galaxy s21 ultra.

The anker power bank charged the phone fully fir two times and the third charge went from 25% to 79%. Please I don’t like to get my phone down below 25% before charging it and that’s why you are seeing 25% as the starting point.

Experience charging samsung galaxy s9 plus using anker power bank: Charging the galaxy s9 plus using the anker power bank gave me a complete three and half charges and I was really pleased with that. The fourth charge went from 15% to 66% before the power bank was dead flat.

Experience charging iphone xs max using anker 20000mah power bank: Using the anker 20000mah to charge the iPhone xs max was indeed a good one as I was able to get four good charges though the last charge wasn’t full as it went from 20% 73%.


You can check out thebest prices for Anker PowerCore Essential power bank from Amazon.


All these examples shows you how long does 20000mah power bank last and as you can see from the above examples, the higher the battery capacity the low the numbers of charges you will get.

Good quality power bank matters a lot

For the fact that I said a 20000mAh power bank will last a good 24hrs depending on your phone battery life and capacity, it doesn’t mean that this is applied to all power banks you see in the market.

Why I’m saying this is because i used my friend 20000mah power bank to charge my samsung galaxy s21 ultra, lo and behold the power bank charged the phone once and went off.

The battery went flat dead.

If you are planning to buy a new power bank and probably a 20000mAh power bank, I recommend you to buy this very  Anker 20000mah power bank or Romoss 20000mah power bank.

Seriously when it comes to buying a power bank or any gadget, the truth is brand matters most. Don’t even go and buy a power bank that isn’t branded or just written power bank even if the price is relatively cheap. Those kind of power bank wont even charge your phone from 20% to 80%  and they are dead flat.

I recommend you to go for a quality power bank that will last long for you and won’t damage your phone battery on the long run.

How many charges will 20000mAh give?

The number of charges a 20000mAh power bank will give depends on a phone battery capacity but be rest assured that you will get a good three full charges with 20000mAh power bank. 

If you phone battery capacity is 4000mah and below, you will get three good charges with a good quality 20000mah power bank.

Poor ones can only offer one full charge 3th/and they are off.

How many times can a 20000mAh power bank charge an iPhone 11?

A 20000mAh power bank will comfortably charge an iphone 11 for a good three before it goes dead flat. 

What I mean by comfortably charge an iphone 11 is that a good quality 20000mah power bank will charge an iphone 11 from 20% to 100% for a good three times before it goes dead flat.

If you are looking for the best 20000mah power bank for your iPhone 11, kindly scroll up and you will see my recommendations.

Related post: Does airplane mode save battery on mobile phone (Helpful tips)

Now you have seen it all on how long does 20000mah power bank last, you can go ahead and get one for your mobile phone and you will see all that I have explained in this article.

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