I have bought at least 4 powerbanks in the last 3 years. Only one of them has been able to serve me well. I bought a pineng 10,000mah powerbank from jumia which ended up being complete fake. It takes just 15 mins to charge to 100% and takes just 10 mins to run down when using it to charge my phone. Plug my s6 into it and it will only gain about 10% battery and the powerbank is dead.. what a waste of money. Of all my powerbanks only the New Age 8,000mah has been able to serve me well.

A lot of people believe powerbanks deliver the true capacity written by manufacturers... this is wrong. For example if u have a 6,000mah battery, theoretically it should be able to charge a 3,000mah battery 2 times, But in reality it WILL NOT. It will only deliver about 4,000mah of charge, that is it will charge ur 3,000mah phone 1 time and the second time it will only charge to about 35%. This is true for original powerbanks. My phone has a 2,600mah battery and my 8,000mah powerbank can only charge it 2 times from 0-100.

In summary, the true capacity of a powerbank is 2/3 of the advertised capacity. So if u have 10,000mah powerbank, just know the approximate amout of charge is can deliver is about 7,000mah. But why is it like this?

Inside powerbanks are 3.7V batteries but the USB standard is 5V. Between the battery and the USB socket is a conversion circuit and this changes the 3.7 V into USB friendly 5V. When converting into a higher voltage you must also convert the mAh into the new voltage. Below is the easy way to do the conversion.

ACTUAL 5V mAh = 3.7 X Advertised Capacity / 5

For a 10,000mAh powerbank – 3.7 X 10,000 / 5 = 7,400 mAh

You still will not get a full 7,400mah from a 10,000mah powerbank. Why? Because there is also a conversion loss. As you use your powerbank the circuit inside that converts 3.7V to 5V USB uses some energy and also creates heat. During this conversion you lose some extra mAh. This can range from 2-10%, so at the end of the day ur 10,000mah powerbank actually can only deliver about 7,000mah of charge. A 16,000mah powerbank actually has a true capacity of 11,000mah.

You can read more from here
https://blog.banggood.com/the-secret-marketing-trick-behind-powerbank-capacity-29982.html


https://www.youtube.com/watch?v=Pf2-p5EYrK8

greenhulk:
I have bought at least 4 powerbanks in the last 3 years. Only one of them has been able to serve me well. I bought a pineng 10,000mah powerbank from jumia which ended up being complete fake. It takes just 15 mins to charge to 100% and takes just 10 mins to run down when using it to charge my phone. Plug my s6 into it and it will only gain about 10% battery and the powerbank is dead.. what a waste of money. Of all my powerbanks only the New Age 8,000mah has been able to serve me well.

A lot of people believe powerbanks deliver the true capacity written by manufacturers... this is wrong. For example if u have a 6,000mah battery, theoretically it should be able to charge a 3,000mah battery 2 times, But in reality it WILL NOT. It will only deliver about 4,000mah of charge, that is it will charge ur 3,000mah phone 1 time and the second time it will only charge to about 35%. This is true for original powerbanks. My phone has a 2,600mah battery and my 8,000mah powerbank can only charge it 2 times from 0-100.

In summary, the true capacity of a powerbank is 2/3 of the advertised capacity. So if u have 10,000mah powerbank, just know the approximate amout of charge is can deliver is about 7,000mah. But why is it like this?

Inside powerbanks are 3.7V batteries but the USB standard is 5V. Between the battery and the USB socket is a conversion circuit and this changes the 3.7 V into USB friendly 5V. When converting into a higher voltage you must also convert the mAh into the new voltage. Below is the easy way to do the conversion.

ACTUAL 5V mAh = 3.7 X Advertised Capacity / 5

For a 10,000mAh powerbank – 3.7 X 10,000 / 5 = 7,400 mAh

You still will not get a full 7,400mah from a 10,000mah powerbank. Why? Because there is also a conversion loss. As you use your powerbank the circuit inside that converts 3.7V to 5V USB uses some energy and also creates heat. During this conversion you lose some extra mAh. This can range from 2-10%, so at the end of the day ur 10,000mah powerbank actually can only deliver about 7,000mah of charge. A 16,000mah powerbank actually has a true capacity of 11,000mah.

You can read more from here
https://blog.banggood.com/the-secret-marketing-trick-behind-powerbank-capacity-29982.html

Not when you use the xiaomi power bank.

luvlyoracle:
Not when you use the xiaomi power bank.

Are u saying Xioami powerbanks don't have 3.7 volts batteries in them? lol. If what they have is 3.7v then u will NEVER get the advertised capacity from them trust me.

Below is a typical xioami 16,000mah powerbank. If u look closely it has 3.6v batteries in it. If u look even further closely it is stated that the true capacity u can get out of it is 10,200mah. I just wish manufacturers can be honest and state ACTUAL capacity from their powerbanks. As a precaution, just take off 25-30% from the advertised capacity then u have a more realistic capacity.

Makes practical sense. Thanks @OP

This is another 16,000mah Xiaomi powerbank. Again they are nice enough to include the true capacity of 10,800mah at 5.1v. The included batteries are 3.75V. When u add energy loss due to heat u will end up getting about 10,600mah out of this 16,000mah powerbank.

Basically all Power Bank follows this rule so xiaomi is not an exception

He's telling the truth.

Original power banks comes with about 80% conversation.

It's expensive. If you need original power bank, you have to pay for it.

Polymer is better.

Nice One Op.
Most Times They Use 0.7 Or 0.8 For Converting The Actual Capacity.. I Am Not Sure If Heat Loss Was Considered Or Negligible.
E.G 16000mah X 0.7 = 11200mah
or
16000 x 0.8 = 12800mah

I'll Always Go With The Former, Not To Get Too Disappointed.

OP u be physics student?

Thank you for the info

Hmm

luvlyoracle:
Not when you use the xiaomi power bank.

See brother, I'm not here to spoil market for anybody, but u see jumia is a no no when it comes to their power banks, I ordered a 20,000 mAh, d power bank charged for 3 good days without leaving d first bar, I ordered another one and I tested it when d delivery man came, but it didn't charge my device, I returned it o. I prefer to go to a phone store to get my power bank than trusting jumia

No power bank is up to the capacity written on it

wow... new thing learnt today

How do I get an original Power Bank?? i Stay in Abuja

this year make it three years I have been using my power bank it comes as advertised 10000mah inside it has 4 2500mah 2.5V batteries connecting them in series and parallels
don't ask me for the brand it doesn't have a known brand name its called cross.
the problem is that we have a lot of fakes in the market

From what I see its like u r a dealer. So which one do u recommend and how do I get it.

Am in Lagos.

Thanks OP, its enlightening indeed

Op, nice information but it appears my new power bank is contrary to your post. It's capacity is 20,000mAh and At 100% full charge, it used 14% to charge my phone battery with capacity of 2600 mAh.

SexyCrixus25:
From what I see its like u r a dealer. So which one do u recommend and how do I get it.

Am in Lagos.

On the contrary I'm not a dealer so I can't recommend anyone. Just do u research before buying an have it in mind that the true capacity is always 20-30% less than the advertised capacity. And if u bought a fake it it might be up to 70% less than the advertised capacity.

can someone show me the conversion of my power bank

now I know why my phone charge slowly there might not beva need for one isbpower is stable and constant in Nigeria

now I know why my phone charge slowly there might not be need for one if power is stable and constant in Nigeria

milky3:
now I know why my phone charge slowly
there might not be need for one if power is stable and constant in Nigeria

No, you need a better USB cable.. The short ones that comes with Nokia are fantastic

AnusOdourInhaler:

No, you need a better USB cable.. The short ones that comes with Nokia are fantastic

I need a better and lasting power bank

I have been using this Apple soft power bank for 3years+ now, though quite expensive when I got but it, but it has served and still serving. 10,00Mah with 3 ports

milky3:
I need a better and lasting power bank

By Xiaomi or fil

Powerbanks use a type of lithium ion battery called 18650. Their voltage when full is about 4.2v and about 3.3v (depending on the protection on the charging circuitry) when low.

Now each cell is rated in mAh (milliamperes per hour) which determines how much charge it can hold and they loose about 20% of their rated capapcities after the 200th charge circle.

Now you should understand that the market is flooded with low standard products which uses poorly built 18650 cells and bad conversion algorithm leading to you not having value for money.

My advice is to go for renown brands.

very informative a thread...Thou I have never bought a Powe bank but this should guide me when am ready for one

@greenhulk you were right about power banks having less than the rated capacity ( that is common with electronic/electrical devices) but your conversion mathematics is wrong. A device rated 2000mAH will deliver 2000mA for one hour irrespective of the voltage as long as the current is 2000mA. The conversion circuit (3.7-5v) only ensures you get the right voltage for the device and doesn't affect the capacity in anyway. Don't forget the moment you step up voltage, you will need lesser current for the same power consumption, thereby preserving the capacity. If it were watt-hr rating your conversion would work but most watt-hr rating for power banks specify the voltage as 5v and not 3.7v. Infacts those 3.7v batteries charge up to 4.2 or 4.3v when the power bank is full and discharge to about 3.5v(or less as it varies a lot) when empty. 3.7v is just nominal and so never used for watt-hr rating as constant volt is required which is the constant output voltage of the power bank (5v) even as the battery drops.


In short mAH rating only considers delivered current with time irrespective of the voltage at which the current is delivered.