Review of USB battery box 6x18650 Qidian

what do the buttons do, that are on the electronic board ?

View from top, the left one is Activation button, while the right is On switch & output voltage selection.

hi
if i put Panasonic batteries in this power bank
3400*6 = 20400

how mah should i take out of it
and how do i do the calculation normally

thanks

If you look at my curves, you will find one for 3400mAh batteries.

It shows that one battery with 10 ohm (0.5A) load will last for 250 minutes, that is 2Ah.

With 6 batteries you will get 6 times as much, i.e. 12Ah.

i am sorry i didn’t get that
my question if i charged my power bank in full ( 20400 Mah )
how many mah i get out from the power bank
for me to calculate how many times to charge my iPad or my mobile

sorry but i am newbie
thanks

12Ah is 12000mAh

thanks
i cant understand this
i have Qidian 5 batteries box i put in it my broken Chinese power bank batteries
it written on them 2200
so i put four of this batteries ( 8800 ) in the box
i made calculation i found that i am getting 6050 mah
so its 68.7%
how come i get 58.8% out of this panasonic and they are a lot better

thanks

The total capacity of your 8800mAh is in 4.2V, when it passed the circuitry to boost to USB 5V, there’re sure some losses there.

Hence, you will not get the full 8800mA from it. (a very rough estimation from 8800 in 4.2V is about 5535mA in 5V)

Read those Panasonic Li-Ion datasheet, to get the full capacity, it need to discharge down as much as 2.5V to get the full capacity,

normal powerbank circuitry cut-off at about 3V, so there’re also some minor capacity which cannot be use.

Hope these helps explain your confusion :slight_smile:

Maybe your calculations are not that precise.

There are two loses in mAh when using a battery box, first is due to the voltage difference and it cannot be changed, the other is due to the converter doing the conversion of the voltage. In this box here the conversion efficiency is about 90%.

HKJ,

With this battery box, can the batteries be left in the box as storage? Is there any discharge, if so, what rate?

Thank You!

-d

Check the list of points just after the "Measurement" heading.

Thanks! I was skimming and was looking for the terms like ‘storage’ and ‘drain’ and didn’t see it. So this box looks good to be able to leave the batteries in there for 6-months (emergency batteries?)

-d

6 months will drain about 0.055*24*31*6 -> 245mAh

Even with only one battery in it, it would not be a problem.

Well after about 8 months of light to no use, my power bank has developed a charging problem. USB output still functions normally, but it only charges the internal batteries to 3.85V, then the 80% LED stops flashing. Charging intitally stopped at the 60% mark and I had to reconnect the charging cable several times before it attempted to charge more, but this doesn’t work once the batteries reach 3.85V. It seems to do this regardless of whether there’s 1 or 6 cells loaded. These are new laptop pack pull LG 2200 mAh cells which have only been used in this power bank. The cells are charging / testing without any issue in my Opus, so they don’t seem to be the issue. I may have to poke around to see if there’s an obvious failed SMD resistor or some other component like the poster with the LED failure.

KuoH

Nice thanks!!

Looks like they have a 5X version that can charge thru a micro USB connector as well

http://www.fasttech.com/product/1457403

I have their 4-cell box, which has a digital display including percentage of charge: http://img.fasttechcdn.com/134/1341600/1341600-13.jpg

I’m wondering how reliable that is — thinking about using it to discharge cells down to 40 percent for storage purposes.

I’ll be trying it, but curious if anyone has done that and checked results (or has another recommended way to take batches of cells down to 40 percent for storage time)

I use my hobby charger to discharge my batteries down to a storage charge. It seems to me that one could hook up a number in parallel and then discharge them all down to 3.7v - 3.8v. I parallel charge cells up to 4.2v so it seems to me that discharging them in parallel should work just as well.

Does it delivers 4amps on the USB-Outputs or on the DC connector only?
Has anyone checked how long it could provide such currents?

Can it be used as UPS ?

There is a new version but with led display that fails to be usedas ups. I think that it is a common problem with all from the same style/manufacturer