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.