Part 1： PN-910 testing
Part 2： 20000mAh powerbank testing
Part 3： Lithium-ion / polymer Li-Po （not 18650 type）
Part 4: Xiaomi Powerbank tested

Part 1: PN-910 testing

I had carried out a test, this powerbank had discharged for 7 hours 20 minutes（4.925V, 0.945A)

i use two 10ohm resistor in parallel , resulting total resistance of 5 ohm, resistance is enough low to get the output of 4.925V，0.945A.


two 10ohm resistor in parallel


display show a little of fluctuation，between 4.92-4.93V, 0.94-0.95A. on average, it is 4.925V，0.945A.


Inside the case contain four 18650 type battery, each one contain 2800mAh of capacity.


measurement taken by vernier calipers, diameter is around 19mm.



The powerbank in the current market are measured by mAh, of course the higher the better.
But, mAh cant reflect the real capacity of a powerbank, why?
Because most of the powerbank is using lithium ion battery, voltage is 3.7V, after fully charge is 4.2V.
When you are using it to charge other devices, its output voltage is at 5V. (USB device must be 5V)
This mean that the 3.7V should be converted into 5V before it can charge or operate other usb devices.
An example, for 11200mAh powerbank,
3.7V x 11200mAh = 41.44Wh = 5V 8288mAh
So we are more concern on 5V output, that is 8288mAh
The conversion is not 100%, there will be some losses about 10% or more.
just take 10% as losses, so we have 8288 x 90% = 7459.2mAh @ 5V
if your handphone battery is 1800mAh capacity, it mean that it can charge your handphone for about 4 times.

what i tested here, i am measuring using power and not mAh, which is accurate.
As you know, VXI= Power
Under 5ohm load, 4.93VX0.94A=4.6342Wh
Because of the measuring time is quite long, i take measurement on every half hour.
Total discharging time is 7 hours 20 minutes.
From calculation, i can get a total power dissipation of 34.13Wh,
the rated power is 41.44Wh ( 3.7V x 11200mAh)
34.13/41.44x100%= 82.36% is the real capacity

This is one kind of fake powerbank.

(shared on facebook, just for comparison)

Just avoid this type of powerbank, even inside is not filled with sand, its capacity is very much lower than the rated capacity.
My tested powerbank has 11200mAh capacity, HxWxL: 21.5mmx71mmx110mm
Each 18650 is around 18mm in diameter
length of 110mm can fit a capacity of 11200mAh, what is the length of powerbank to fit 20000mAh or 30000mAh? you can do the calculation.

Beware, there exists of fake powerbank which is same as what i tested. The one i tested is 100% original.

This post has been edited by x-treme: Jun 4 2014, 09:18 PM

Part 2: So called 20000mAh powerbank test

i had borrowed 20000mAh powerbank from my friend. Due to warranty reason, my friend not allow me to open it.
tried some method to figure out how many 18650 battery inside the powerbank, lastly i use torch light and saw there are 6 18650 battery.
What is the capacity of each 18650 battery i'm not sure, but i can test and prove it.



Written 20000mAh, made in Taiwan
Written 2 output current: 2.1A and 1.0A. After i tested, it is just a parallel output from same source, not separated.



This set up is similar with my part 1 test, using 2 10ohm resistor in parallel, resulting 5ohm resistance.
Output current stable: 4.79V, 0.94A


Result are recorded, total discharge time is 4 hour 40 minutes. Total output power is 21.01Wh, only 28.4% is the REAL output power.
Rated capacity is 3.7V X 20000mAh = 74Wh (vs 21.02Wh Real)

[My tested PN-910 had discharged for 7 hour and 20 minutes, total output power is 34.13Wh, 82.4% is the REAL output power]
Rated capacity is 3.7 x 11200mAh = 41.44Wh (vs 34.13Wh Real)


The 20000mAh powerbank had been tested for twice because the first time test i had over estimated it can discharge for at least 5 hours.
But it is actually less than 5 hours.

Dimension measurement by vernier calipers（20000mAh）：135mm x 71mm x 24mm
(my friend said this unit was selling with price tag of RM110)

This post has been edited by x-treme: Apr 29 2013, 11:48 PM

PART 3: Lithium-ion / polymer （not 18650 battery，18650 is similar to AA type of cylindrical battery）

Borrowed another powerbank from my friend， it say it is using Li-Po ，smaller and thinner size.（diameter of 18650 battery is 18mm，this one is less than 18mm thickness）
The rated capacity is 5000mAh，everyone can guess how much is the real capacity?


Battery inside is thin, but is it soft one, if you press it, it will not restore back to the original position.


The voltage regulation is not good as PINENG powerbank, it fluctuate much more.
Some of the data taken:
4.77V 0.92A
4.80V 0.93A
4.64V 0.89A
4.48V 0.86A
4.37V 0.84A

From my calculation, the real capacity is only1.82W
Rated capacity 3.7Vx5000=18.5W only9.84% is the real one.
this powerbank had been used for 1 year plus, now only remain 9.84%，1.82W even can't charge iphone for half time.

For your information
Even though there aren't sand inside the powerbank, it doesn't mean it has real capacity.
For example: I opened a powerbank, inside contain 4 pcs of 18650 battery, if I said each 18650 battery has capacity of 10000mAh, 4x10000= 40000mAh. This can charge note 2 more than 10 times. Will you believe it? Don't laugh, there are people will believe this.
Remember the highest capacity of 18650 battery is 3100mAh，manufactured by Panasonic. Those who said it has 5000 or 10000mAh are cheating.[/size][/backcolor]
If the powerbank is not using 18650 battery, but is Li-Po type, the price is much higher than 18650 type. Li-Po is extra thin and slim. Manufacture price also higher. Those who sell at cheap price, you know la

Another sharing
Anyone can guess what is this ?

It is battery but not AA type，is 18650 battery，it is used in our laptop battery, this is called 6-cell type.
This battery I disassembly from Lenovo laptop, rated capacity is 48Wh, each 18650 battery contain 8Wh, or 2162 mAh.

Everyone can see that even laptop also use 18650 battery, don't think that this type of battery not good, it is cheaper than Li-Po type.

This post has been edited by x-treme: Apr 29 2013, 11:48 PM

On the first sale of Xiaomi in Malaysia, I managed to grab 2 units of powerbank.
Last week I just get the unit delivered by UPS.
This time I carried out the test using a battery tester, no longer using the manual way to calculate the capacity, because it consumes a lot of time if calculate manually.

Let's take a close look at Xiaomi powerbank. The case is made using aluminium.
The weight is a bit heavier than the Pineng PN910 (also contain 4 cells)
This Xiaomi powerbank carry a capacity of 10400mAh, which is 2600mAh per cell.
I not sure whether my unit is made using LG or Samsung brand as I don't want to disassemble the unit.
Spec:
Input 5.0V 2.0A
Output 5.1V 2.1A
Rated capacity: 3.6V 10400mAh / 37.44Wh



Ok let's start the first test. Although Xiaomi powerbank capable to output 2A@5V, I want to test for 1A output to compare with Pineng PN910. (since different output current will affect its efficiency)

Updated test for 1A@5V
Voltage during discharge 4.97V


Current during discharge 1.00A


The result is here 7 hours 9 minutes.
7.15x4.97x1.00=35.5355Wh
35.5355/37.44= 94.91%



This post has been edited by x-treme: Jun 22 2014, 08:58 PM

The next 2 days, after fully charged the xiaomi powerbank, I carried out the second test.
I used 2A discharge so I can shorten the test time(Now working already I have limited time do the test)

Voltage during discharge @2A


Current discharge set at 2A


Total discharge time 3 hours 41 min.


Capacity measured @ output voltage 4.85V is 7390mAh



Calculation using time- 3 hours 41 min
3.68hours X 4.85V X 2A =35.696Wh

Calculation by capacity measured
7.39Ah X 4.85V= 35.84Wh

So we use this value 35.84Wh/37.44Wh x 100% = 95.73%

I really can't believe even at high current output 2A it does give the efficiency above 95%

The unit did not getting warm when discharging @1A but it get hot when discharging @2A.
The aluminium case helps a lot to dissipate the heat to keep the component cool.

Anyone tested the Xiaomi powerbank can share with us.


This post has been edited by x-treme: Jun 4 2014, 09:17 PM

Pineng PN910 powerbank tested again after 1 year 3 months.
I no longer using the manual way ( 2 multimeter and resistors) because it consumes a lot of time when testing.
Now I using the tester unit which is capable to test car battery, lithium battery or powerbank etc.
Thresold voltage, discharging current can be manually adjusted. It is much more accurate than my test last time.
Ok, now let's see the 1st result what we got here. The testing are based on 2.1A output port.

I discharge the powerbank using 1A current setting.


The voltage@1A output which is 5.05V


What I got the result here. 6 hours and 10 minutes.


5.05V x 1.00A x 6.167hours = 31.14Wh

rated power= 41.44Wh

31.14/41.44 x 100% = 75.14%

The next test is discharge using 2A, which I never test before.

I discharge the powerbank using 2A current setting.


The voltage@2A output which is 4.70V


What I got the result here. 2 hours and 31 minutes.


4.70V x 1.99A x 2.52hours = 23.57Wh

rated power= 41.44Wh

23.57/41.44 x 100% = 56.88%

Conclusion is the battery starting to degrade after 1 year of usage.
The conversion efficiency is poor on 2A output, compared to 1A output.
Xiaomi have better efficiency than that.

This post has been edited by x-treme: Jun 10 2014, 01:56 PM

I just wanna know what brand is good. Might get one soon

this brand PINENG quite good, from what i have tested.

look good where to get it?

you can find in mobile accessories ...

good post, thanks for doing the testing.

i highly agree that those powerbank which rated 20-30k above are mostly fake. how can it have so much 'power' when the size and weight are almost the same like other smaller power bank. it's like saying they can make AAA battery lasts as long as D battery.

This post has been edited by nghj: Apr 30 2013, 07:50 AM

yup. for the 18650 size of battery, the highest capacity is 3100mAh, but it is expensive than 2600 and 2800 type. for those cheap powerbank they wont use that 3100mAh. only use around 2000-2400 like that or even lower capacity, so it can save cost. but if it using Li-Po type, it wont be so cheap also.

there exist 20k or 30k capacity, but it is big and expensive, rm300-500 or more. this type can be used for charging laptop.

Bro what's the self discharge?
How long will my this power bank take to charge my Note 1, 2500Mah

Btw i have this.
I plug to phone n use non stop while charging, can go up to 90minutes.
If plug to phone n leave, can charge full n still got balance power.


Major Parameter:
1)Input:DC5.0V,1000mA
2)Output :DC5.0V,1200mA
3)Battery:5000 mAh
4)Cycle Life:>800times
5)Self discharger :<0.05Ma



This post has been edited by Gurvin Abruzzi: Apr 30 2013, 08:41 PM

thnks for this

great job dude

self discharge i can't test. so i don't know.
the "how long" is depending the rate of flow of the current to charge the phone.
for an example, my phone accept the current rate of 950mA therefore 1.84 hour can fully charge my 1750mAh battery in AC charging mode.
my phone accept 450mA current rate for usb charging mode. it will take longer time.

So it is depend on which mode you are using to charge your device.

what u think of this one?
using li-po

http://www.myimart.com/deal/super-power-12...pn4875v?aref=DS

i din't heard that brand before. And i saw there is 73% why don't you doubt it ? sell without earning ? i can say the original price is cheaper than 109.

82.36% is the real capacity..what about the rest?...and what's ur view in yoobao?...as good or worse?

For me, whatever brand, the REAL original is the best, the FAKE original always the worst one.
The reason why the REAL original Yoobao is more expensive because it is more famous.

thanks for sharing

Means that doesnt necessarily means original yoobao is better power bank??

as long it is original, brand didn't make much different.

for example, yoobao 11200mAh and pineng 11200mAh. Do you think yoobao will give higher capacity than pineng 1 ? actual capacity only different in few % only.

nice.

so if you were to buy one which will you suggest?

PN910. high capacity at affordable price.

how is it less quality than yoobao.

yoobao is pretty good too right.

btw, why all the powerbanks that i've seen is all china brand.
no apple, ang moh brands

not the problem for the 18650
it just the grade of the battery problem,
normally have grade A,B,C

those china made powerbank mostly Grade B to C
because it was very cheap and those Grade A mostly reserve for own use
they not sell much outside

and also 18650 is 3.7V convert to 5V, your calculation is good!
count with watts, because i buy a powerbank at japan, panasonic 8800mah, it mentioned 3.7V 8800mah at the back
it does charges a iphone 4 and galaxy s2 to from 20% to full, and still haven't finish

that one i can't comment much. how you want to measure the built-in quality?
but for battery it is using the real capacity.
those not made in china one, you know the price.
with the same spec it can double the price.

i don't know how to differentiate those grade A B C.
of course if you buy the better cell, it will last longer, and it will cost more.
nowadays many powerbank in the market are with fake capacity. for example 30000mAh
how can a 6cell / 8cell powerbank equip with 30000mAh?

off topic abit

so now i know where my e-cig 18650 battery come from.. haha

currently using this battery

you cant differentiate it with it outlook, mostly we just can differentiate
with the price, good thing not come with a low price, the grade C, i see a report that days, it just about 40% of it stated mah, which grade A is about 95%+- Grade A battery is used by samsung, panasonic sanyo those big company, while Grade B and C we can normally buy at the market

I have disassemble an yoobao 6600mah type, 3 Red color battery, and it stick with the glue stick glue, i haven't pull it out,
i planing buy at least 6 18650 to install and use it

at taobao.com china website, their have some panasonic brand 18650,
i will buy some for testing

wow, it was a samsung!

dafuq?

ecigs using samsung rechargable batt?
hahaha

ICR 18650 = lithium cobalt oxide (traditional) cylindrical cell
IMR 18650 = lithium manganese oxide cylindrical cell
IFR 18650 = lithium iron phosphate cylindrical cell

found this,
however..........
not really know what is this

double post is double post!

This post has been edited by foohoa: May 24 2013, 12:07 AM

so had you tested for the real capacity for the yoobao 6600mAh and the efficiency ?
how about the grade B ? 80% ?

now i very hard to believe those.
many things have imitation.

grade b between 60 to 80% only.....
and my yoobao die in few month, that i brought from china
they actually show me 2 type packing, at the outlook was same

1 with yoobao logo, 1 without, and the different is RMB20 only....
b4 this, it manage to charge an galaxy s2 and it about to die

planing buy this

http://item.taobao.com/item.htm?spm=a230r....&id=13485304566

my fren is agent of taobao, they allow me buy anything!

so...
want bulk?

haha. so did you buy the original yoobao ?
now you are going to replace the battery by yourself ?
by the way my gf is taobao agent too. i can buy anything from taobao, can ask them how to pack also.
there are something powerbank, which can replace battery by your own. i am planning to get one to test.

yes...
i buy the ori, but...
i search online, acutally china ppl hate yoobao
i planing to take out the board, and build a battery case, store at least 6 battery,
look might be ugly, but i must be better then any power bank at the market

about these you can refer to batteryuniversity for more information.

try to take out the yoobao 6600mah
which looks triangle
they look quiet honest
it was 3 ultrafire 3800mah

this


This post has been edited by foohoa: May 24 2013, 12:30 AM

haha, but yoobao is quite popular in Malaysia. When you mention powerbank, they will think about Yoobao only. Ask someone to recommend, also only yoobao.

good luck in your modification. but something i can share here.
the changing of lithium ion battery (18650) in laptop battery, they need to measure the internal resistance and get the nearest value of internal resistance for those battery to be connected in parallel.

really? ori using ultrafire battery?

wow, ur pn-910 that top 2!

http://top.zol.com.cn/compositor/688/pocketpower.html

wow, ur pn-910 at top 2!

http://top.zol.com.cn/compositor/688/pocketpower.html

they actually like pisen
malaysia market have pisen?

This post has been edited by foohoa: May 24 2013, 12:38 AM

but i dont think this ultrafire is ori la
i just use about 2 to 3 month, and it die...
full charge and leave it for few hour, and the indicator light go to 3/5
and full charge again, few hour 3/5 again......

the ranking doesn't mean anything. it is just the popularity.
pisen is more expensive than pineng.
you may look around here i think most people want a cheap and good quality.
so if it is not cheap AND good quality, it is very hard to sell.

may be there are some problem with the circuit ?

dont think so,
because i use it to charges something i will run out at about 20 min

ok. try replace the battery and see whether it works or not.

Yoobao is just a brand. It depends on the quality of the internal components.

Where did you buy the 18650? I'm looking for a few to replace my netbook's cells. 2 are dead.

That;s the battery chemistry, which allows for different charging curves. I'm not too familiar either.

x-treme, this is a fantastic thread. Thank you for the testing and information. This internal resistance for parallel connection info is also useful, as I thought you merely replaced the battery of like or greater capacity.

Will pin this to Note 2 thread.

you can ask at Vapors Community FB page https://www.facebook.com/groups/myvaporscomm/

normal price for one 18650 battery is around RM22-30. dont buy if the seller put price more than RM32. find the ones who sell around RM22-30 only.

This post has been edited by mi-g: May 26 2013, 06:58 PM

there are 2 types 18650, 1 is with protection circuit and the other 1 is without protection circuit. so make sure you buy the correct 1 to use.

and whats the different with or without one bro ?

the protection curcuit mean it limit the current, if no protection, the battery just give as much as current it can supply, so if something short, it was very dangerous

Interesting thread!! battery tech

Actually, AW and Eagletac are producing protected 18650 with capacities of 3400mAh, unprotected ones IIRC goes up to 3600mAh if i'm not mistaken.

by the way, where is your location, would be interested in passing you my power bank for testing or either could you lend me your resistors and the USB connector for testing?

I have the Yoobao YB-655 rated at 15600mAh and also an EXC with li-po batteries rated at 12000mAh. Would be interesting to test these 2 power banks as they are relatively new in the market as well.

Ultrafire products are crap FYI. I've been playing with flashlights and Ultrafire are crap in the flashlight industry. Their batteries are also way overrated in terms of capacity. That 3800mAh capacity is definitely fake. And its highly unlikely they will use Ultrafire batteries in a power bank as it's most likely a protected cell as well. Nobody uses a protected cell in a multi-cell device with it's own circuitry.

protection circuit also protects from overcharging(above 4.3v straight cutoff) and also overdischarging(cutoff below 2.7v). If protected cells are used in a high drain device(like in an e-cigg), the voltage may drop to below 2.7v due to the high current draw and activate the protection circuit which is why you don't see people using protected cells in high drain devices like e-ciggs and high-powered incandescent flashlights.

so far i had saw about 3400mAh battery. but i don't think it will be used for powerbank battery. Quite expensive.
Erm, this few weeks will be busy for my fyp and final exam. can test but not now.

ya that's right. but how can they detect whether it is on low battery? because lithium ion battery will spoiled if voltage drop less than a certain thresold.

They rather add more cells than to purchase the 3400mAh cells. For example the YB-655 rated at 15600mAh means each cell is 2600mAh, but if you use 5x3400mAh you can achieve a higher capacity plus a smaller power bank but it's just not economical for them I guess.

Or either could you pass me a few pieces of your resistor and maybe your DMM so I could test it myself and post the results here as well? Your DMM comes with logging features?

And if you're talking about people who use unprotected cells, for eciggs once the battery reach a certain voltage the flavour and smoke amount will be different so that's a sign that the capacity is running low. Similar for a flashlight, once the battery reaches a certain voltage the light output will lower down showing the battery's almost up. Usually when this happens the battery should still be above 3.0v but unless the user is completely ignorant then yes he can run the battery down way past 2.7v and maybe even down to zero. By then the battery had been permanently damaged and had to be disposed of. That's why users who handle unprotected li-ion cells should be educated on it's characteristics and charging/discharging methods.

If anyone of you are looking for high quality power bank, feel free to visit my thread. Satisfaction guaranteed. Check out the feedback about it.

can't also. my fyp still need use these tools.

don't have price ? how you determine it is high quality powerbank ?

hello,do u noe yoobao 13000mah..usually can charge s3 for how many times?

i opened up my fake yoobao 11200mah powerbank.
inside only got 4x2200mah 3.7v batteries.

how do you know it is 2200mAh?

i see. may be the actual capacity will be lower than that.

i also opened my original Yoobao before, found 4x 2500mAh cells instead

weird thing is it's confirmed an original.

ya, maybe its low quality cell. i dont 'feel' that it lasts as long as it should.
8800mah@3.7v should be around 6512@5v. after 87% eff, its around 5665.
should be able to fully charge my phone (2100mah) around 2.7 times.
i only use to charge phone at night with airplane mode on, i can only use for 2 nights. after that, the powerbank is flat.

swapped with fake unit?

may be you can try buy the 18650 cell on your own and replace it.
See whether there is improvement or not.

nope it was an ori. confirmed original from the SN and also matches all 'original' markings found online

oh i see. may be the powerbank produced in different batch will use different type of cell. so only some powerbank have better quality. We can't see what cell used inside, so it just depend how lucky you are.

How to prevent the powerbank from frying your phone motherboard?

Do we need to check the output capacity of the power bank?

I had bad experience with the Yoobao 11200 mAh powerbank. I have to send my Samsung Galaxy Note for replacement of motherboard after charging overnight with it and later when I had the same experience with Nokia Lumia 900.

The Yoobao was original cost I had send it for repair earlier at the serveice center in Jalan Segambut.

Any advice would be most appreciated.

are you sure with only charging with powerbank will fry your phone motherboard? how about normal ac charger?

there is a built in circuit to limit the current on phone motherboard. i had tried using 5V 3A charger to change my phone. when i measure, it only accept the current upto 1.1-1.2A and not 3A.

there are also built in circuit for powerbank itself, that's why it will have 2 output : 1A and 2.1A.
the rating is showing the max current that it allow, not must be exactly 1A.

so far i tried my times for overnight charging no problem on my phone. i like the feature that it will auto cut off when my phone is fully charged.

do yoobao have auto cut off feature?

Based on my estimation, PN-912 16800mAh will have 6 drycell?
1 cell=2800mAh
Am I right?

sorry i don't know about that. you may ask the yoobao seller or users.

yes, you are right.

There is no problem with normal AC charger. So I can use any type of power bank irrespective of the higher output rating of the mA compare to the smartphone input charging capacity.

Maybe I have a faulty Yoobao powerbank? How do I test using multimeter?

I do not dare to use another phone to charge again after it fried both my Samsung Galaxy Note and Nokia Lumia 900, fortunately both of them still under warranty. After charging both my phone went dead. Cannot on it back using what ever method.

So how do we test the power bank device that it is working properly?

How do we determine if the device has auto cut off when the batter charging is fully completed?

Just wanna share what I find.
Maybe to those who WTB new cells can refer to this thread.
https://forum.lowyat.net/topic/341954

It seems that they use samsung cell.
But I dont know if they sell the cell only.

*also found this Sanyo cell which is 3400mAh.

http://www.lelong.com.my/evic-sany....

This post has been edited by coklatua: Jun 2 2013, 05:20 PM

the pineng 910 normally sell how much?
how many hours dicharge at 1A?

i wonder whats the max capacity that the circuit board can handle.
maybe can add few more cells in paralel to increase the capacity.

about this i will reply when i free, now still busying for final year project.

but how are you going to connect these battery? if i not mistaken they use nickel plating right?

i tested for my unit and the result shown in first page. around 7 hours continuous.

may be you can try on it and share here.

i can connect a few wires here and there
but i'm not very pro in electrical/electronic stuff.
what's the worst that can happen?
fry the board and the usb charger?

worst case, it melts your plastic case, explosion may be?
remember don't connect in reverse polarity, that is the most important.

Yeah, need to find those soldering tabs.
Like this, http://www.batteryspace.com/Component-1-pc-Soldering-Tab-for-Li-Ion-/-LiMnNi-/-LFP-18650-battery.aspx
I wonder those electronic hardware shop have this.

but you will need spot weld too.

I think I'll just solder it.
Like in this video,


Maybe I will try refilling my dead laptop battery my self.
I think I just need the 18650 cells and the soldering tab to make this project happen.
Need to wait until next month since on tight budget right now to buy cells.