gidimasters:
Buy Romoss Sense 4P 10000mah Power Bank here... Contact on siggy

Elvin001:
This is an eye opener... Thanks Mr OP

Mikaelson21:
My remax 10400 mah power bank I bought since 2015, is still serving me efficiently till today...

WeNoGoDie:
Nice info. But where can I get an original Xiaomi power bank with that is 98% efficient. I don't trust anything on aliexpress.

mhisTessy:

Hav u tried eBay?

WeNoGoDie:
@Op Trendy247. Please why doesn't this 25% to 30% conversion loss also affect the mobile phone batteries themselves. Seems to be limited to powerbank batteries only.

For instance brand new infinix phone with 4000mah battery will give you full 4000mah output in usage.

They're both batteries. Lithium ion/polymer.

Trendy247:

There is no conversion circuit for smartphone batteries because the output is already 5V, unlike power bank batteries whose output is 3.7v...

Converting this 3.7v to 5v so it'll be able to power your smartphone is where the conversion loss comes in

WeNoGoDie:


Smart reply, straight to the point. But if its possible to make mobile phones with 5V, is it not possible to make powerbanks with 5V too so they won't need conversion circuit.

I mean some smartphones double up as powerbanks with OTG reverse charging if I'm correct.

Trendy247:
You have an original real capacity 10,000 mAh power bank, and that should charge your 1500mah phone about 6 times, right? Well, here is where the confusion begins.
What the advertised capacity actually tells you.
The rated capacity is what is actually inside the powerbank, the physical battery.

Inside a 10,000 mAh power bank.

This powerbank has 4 3.7V 2,500mAh batteries, together that equals 10,000mAh and this is correct.
But USB is 5V!
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.

How to calculate theoretical USB output capacity

A simple equation can be used to convert the 3.7V into 5V.
ACTUAL 5V mAh = 3.7 X Advertised Capacity /5

For a 10,000mAh powerbank – 3.7 X 10,000 / 5
= 7,400mAh
So a 3.7V 10,000 mAh powerbank really only supplies 7,400 mAh at the 5V USB connection. So straight out of the box is a 23% reduction in the stated mAh. This is not the actual experienced level as there is also conversion loss.

What is 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. There is a wide range in conversion efficiency and most brands don’t state the losses, Xiaomi has prized themselves on their conversion efficiency chips which are up to 98% efficient, meaning you only loose 2% off your battery power in the conversion. Some others can consume as much as 10% during conversion.

Why don’t they just state the actual output?

They don’t need to as technically that is what’s inside the box and most people have no idea. By not giving the actual 5V output brands can reap these benefits;
>Manufacturers can have a higher number of mAh for their powerbank and sound more powerful.
>It avoids the talk or testing of conversion loss and brands with low efficiency conversion chips can still market them in the same league as other efficient brands.

Some manufacturers will state in the manual or in small print on the device but most will not state anything other than the 3.7V mAh. As a general rule I would recommend taking 25% – 30% off the advertised capacity straight away and then you have a more realistic indication of performance.


This power bank actually states both capacities, you wouldn’t notice it though unless you are one of the people who actually read product labels.

This one has 16,000 mAh but only has 10,200mAh at 5.1V.
It is a very gray area and not common knowledge but I hope this has shed a bit of light on how powerbanks are advertised and busted the classic assumption that dividing the rated capacity by your phone battery capacity is an accurate measurement of actual number of recharges, in reality, it is far from it.
You are now a powerbank expert and next time you are on the prowl for a new one, you'll act as one.
http://obototo..com/2017/09/power-bank-capacity-secret-marketing.html?m=1

sfinkzslot:
this OP is brained

teewhydope:
cc lalasticlala

Geofavor:
Seems Nice and accurate, unless proven otherwise.....

Lalasticlala.