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

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!

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

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?

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

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

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......

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

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