Capacity Test of Fake 18650





Introduction: Capacity Test of Fake 18650

About: Hi, I'm Nemeen !, Electronic and robotics enthusiastic. This is my channel 'Nematic !' I will be uploading on and about awesome Electronics Tutorials, Projects and How To´s You can always comment below...

In this Instructables let's find the capacity of Fake 10400mAh Power bank.

Previously I used This power bank to make my own power bank because I bought it for $2.

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So let's get started

Step 1: Opening

Let's first open the power bank

One's we have opened it cut the wires of power.

since there are 4 batteries and the total capacity is 10400mAh so the capacity of each battery is 2600mAh

Step 2: Charging

Battery was not fully charged so first charge.

let's first charge them using TP4056 module

Step 3: How to Calculate Capacity

We can simply use 1ohm 5 w resistor in series with the battery to test the capacity

but, voltage will decrease over the time and so our current ( resistance will be 1ohm)

and in this case we need to use integral function which is quite inaccurate

Step 4: LM358

Since using integral will be quite inaccurate let's use constant current source.

we can built a constant current source using LM358

let me explain how it works

1) When Vin is higher then Vref output is high which turns our MOSFET On

When MOSFET is trued on there is voltage drop across the resistor and our Vref is now High

2) When Vref is higher than Vin Output is Low and this cycle repeats

Step 5: Capacity Test !

One's the circuit is done adjust the potentiometer to get the current of 1A

It took 15 min for the battery to discharge completely.

Step 6: Calculation Time

Alringht so the,

Current was 1A

and time was 0.25 hr

so the capacity of the battrey is.....










Step 7: My Thoughts !

I think they forgot to divide Every thingby 10

Because Actual capacity of the Power bank 1000mAh and not 10400mAh


The capacity of battrey is 250mAh and not 2600 mAh

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(If there is Any Mistake Please feel free to tell me in comments)



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    exact copy of great scott? nice

    Nice Physics Math calculation in Electronic Field my friend... Continue studying this field and learn more about Quantum Electron Arithmetic Calculations and Quantitative Arithmetic Calculations of Electrical Energy... Excellent demonstration my friend...

    I used a discharger not known the discharge resistance, the values shown to discharge 1A current from 4.20V to 3.0V took 23 min 17 sec, can you calculate the mAH?

    1 reply

    Here you can find a very good list of 18650 battery tests, including top brands, and cheap/fake ones too.

    250mAh seems unlikely low. I would repeat it, even with lower currents.

    The quoted mAh capacity on most battery labels are for smaller current draws; thus, a 1000 mAH battery seldom delivers 1000mA for 1 hour. However, it will come close to delivering 10 mA for 100 hours! Of course some lousy batteries won't even do that ! Your test should be really conducted on the expensive (not cheap imports) to make sure. Somehow I suspect even they will not be significantly better, at least for the extra bucks you'd have to pay for them.

    I think we probably must be careful with products made from China.

    7 replies

    do you know one constructor of batteries that is not made in china ?

    for my part... no one !

    samsung, LG, Panasonic,motoma are 4 different brands that I recommend having tested both for capacity and load capability

    And they are often the most counterfeited brands too boot.

    It takes a bit more effort to beat the counterfeiters at their own game than simply buying brand label.

    About the only certainty is brand name batteries are always by far the most expensive costing 2-4x as much as the generics and the counterfeits.

    Even then you could still buy a bad one simply going on price alone from a seller who takes advantage of people who think price = quality.

    I think probably many parts or components of electric device are made from China. But I highly recommend that we should not buy products with unfamiliar brands, low price, no warranty that comes from China.

    I agree that Xiaomi is a good and big company which supplies many useful products. However, there are numerous companies that they are making largely range of fake products. We should be aware of that.

    On the other hand, we can use various electric devices with global brand such as LG, Samsung, Electrolux, Sanyo, Sony.. These are made from Korea or Japan or even Hong Kong.

    Panosonic are made in Japan I guess

    Very true we must be careful of things made in China, but good luck finding things that aren't made there these days! I think the best thing is to pick major brands, read reviews, etc.

    You should be wary of buying by price rather than quality.
    If you want to buy from a foreign supplier in any country and pay the lowest possible price you will not receive a good quality product and will have no warranty
    If you buy from a local retailer you will be able to return it so they make an effort to make sure they have sourced good quality parts and will charge you accordingly.

    As Li-Ion batteries age, they lose capacity.

    Also an inadequate charger can cause a rapid reduction in charging due to a poor match in the specific requirements for each brand of li-ion battery out there.

    If you're going to try and figure out the capacity of used batteries like that try an opus charger custom made to charge li-ion batteries and rated highly. There are several versions out there, and I think the one that gets it right the first time are chargers with hardware update 2.1 and newer.

    While they can also be counterfeited, the manufactured does try to make it possible for consumers to have confidence in their purchase. You do have to read the small print in ads though, and see if it comes with some sort of hard to imitate proof of origin.

    Opus chargers give a good statistical breakdown of what to expect from both a new battery and old ones after it charges.

    It also has a discharge/refresh cycle for old batteries that can help restore some capacity lost due to time or being charged by a poorly designed charger.

    It has several other functions for li-ion that heavy users will find very useful.

    To be clear, it's not just the li-ion batteries mass produced in China by anonymous manufacturers that are sketchy, but also the cheap, poorly made mass produced li-ion chargers that are a big source of the problem often attributed to the batteries alone.

    Using a poorly made charger can dramatically shorten the life of even the best made li-ion battery.

    1 reply

    I should have said specifically made to charge li-ion batteries that can also charge other types of rechargeables, because it seperate circuitry for each to match their specific requirments, rather than custom mad.

    Your not the only person to notice this practice by Chinese suppliers of Li-Ion products.

    Battery capacities are often misrepresented and they seem to get away with it.

    Your analysis of the op amp based constant current source is incorrect. The FET is not SWITCHED on and off. If it were, this circuit would be an oscillator (which is possible with an unstable circuit). What a constant current should do is BIAS the FET so that the FET is only biased "on" enough to ensure that the Voltage drop across the current sense resistor is sufficient to balance the op amp's reference Voltage input. This is done within constraints of the op amp's open loop bandwidth.

    Not all Chinese parts are bad. They can't be, since even Japan outsources manufacturing to China. I suggest you repeat your testing on "known good" batteries and compare the results before you make your final judgement.

    I think that we can have another solution for this by buying good cells and replacing into the case :))

    I think that we can have another solution for this by buying good cells and replacing into the case :))