18650 batteries 'extreme' capacity - real mAh values?

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ArminVanBuuren

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I'm looking for 18650 batteries. I know there are some high quality brands, such as Panasonic, but I live in a 'backwards' country where they swindle even these brands... I could not be sure if they are not fake. I would probably rather go for some cheaper brands, such as these:

**broken link removed**

A lot of people have bought this. Are there any test available? Such as measuring the real capacity? I doubt it can supply 5 Ah - is it even possible?

Thank you.
 

Your links to battery testers do not test a modern Lithium battery, instead they test old Ni-Cad or old Lead-Acid batteries.
Since a Lithium battery can supply MANY amps of current and the metal Lithium can catch on fire they are dangerous. Some Lithium battery cells have a "protection circuit" inside that limits the charge voltage and discharge current to prevent a fire. But a Chinese company is selling a fake protection circuit that looks identical to a real one.
 

The tests of "moder Lithium battery" would not help either; I doubt they would test these UltraFire "garbage".

In my country, they sell a $18 Panasonic battery, which really looks like an original. But they claim there is ABSOLUTELY NO protection circuit. I conclude these are fake as well, in this country I live, this battery type is not yet spread, and the stores that provide it swindle on it selling fakes.
 

dont expect half the announced value of no brand capacity batteries ...
even when 2000mAh should be more realistic ...
 

Kripton2035 said:
dont expect half the announced value of no brand capacity batteries ...
even when 2000mAh should be more realistic ...
Click to expand...

That's quite sad :-( Though more than 1500 people bought it:

**broken link removed**

Its real capacity is only about 2000 mAhs?
 

The old adage: "if something is too good to be true, then most likely is not true" still holds.

Unfortunately, the only way I can think of to ascertain the validity of the claim, is to perform the tests yourself.
 

Lots of people buy cheap Chinese junk on E-bay. It is so cheap (cheep, cluck cluck) that they do not care if it is no good.

I have a hobby of radio controlled model airplanes. They are powered from Lithium-Polymer (Li-Po) batteries. I buy name-brand batteries from my local hobby store and one time directly from an American manufacturer. My friends buy VERY cheap Chinese batteries from Hobby King in China. A battery test shows that the batteries from China are absolute JUNK! The yellow and purple lines on this graph show how bad the cheap Chinese batteries perform compared to English and Japanese batteries:
 

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Audioguru;

very interesting plot. I see you created it with "Logview". From time to time I require to perform similar analysis.
From a Google search I can see a German company. Is that the software that you uuse?
 

schmitt trigger said:
Audioguru;

very interesting plot. I see you created it with "Logview". From time to time I require to perform similar analysis.
From a Google search I can see a German company. Is that the software that you uuse?
Click to expand...
I did not make the graph. I copied it, other battery tests and some graphs of motor power. Some of the cheap Chinese motors are powerful but burn out soon.
One hobbyist believes the cheap Chinese motors have no lubrication on their bearings (maybe oil costs more than the motor?) so he lubes his Chinese motors and they last a long time.
 

ArminVanBuuren said:
That's quite sad :-( Though more than 1500 people bought it:
**broken link removed**
Its real capacity is only about 2000 mAhs?
Click to expand...

over the past years I bought a significant number of batteries on ebay, dx, various low cost sites.
each time I measured them on my ELV8500 as soon as they arrived
when it's 30% less than the advertized capacity value, I ask for a refund, ... and always get it.
I once got batteries that where 15% of the marked capacity !
people nerver measure the battery capacity, they simply don't have the instrument for that
so they trust the seller, they shouldn't .
on dx now, you can see that they add quotes to the battery capacity, or gently add "manufacturer rated" ...
cut the announced capacity by two, and if it is more then you're lucky.

one of the "lucky" buyer of these batteries said
Liar sells old used batteries as new. 1/10 stated capacity. no refund, garbage
Click to expand...
 
Last edited:


This is very important research. So I should expect about 50 % ... 10 % of the advertised capacity only? And when it's under 30 %, you get a refund automatically, is there any law on this?

"people nerver measure the battery capacity, they simply don't have the instrument for that"

could you describe how to do it?
 

It is easy to measure the capacity of a Lithium rechargeable battery cell.
Its voltage is 4.2V when fully charged and is 3.2V when almost dead and the load should be disconnected. Simple arithmetic calculates an average voltage of 3.7V.

1) Apply a load. A 3000mAh cell can easily provide 1A for 3 hours if it does not have a protection circuit inside. The load is 3.7V/1A= 3.7 ohms which is not a standard value. If you use 3.9 ohms then the resistor heats with 4.5W so use a 10W resistor. The average current will be 3.7V/3.9 ohms= 0.95A.
2) Time it while measuring the voltage of the loaded cell. Stop it when the voltage has dropped to 3.2V.
3) Calculate the amount of average current in 1 hour. That is the capacity.
 

1) fully charge the battery, and disconnect charger
2) Apply a load. A 3000mAh cell can easily provide 1A for 3 hours if it does not have a protection circuit inside. The load is 3.7V/1A= 3.7 ohms which is not a standard value. If you use 3.9 ohms then the resistor heats with 4.5W so use a 10W resistor.
3) Time it while measuring the voltage of the loaded cell. Record or log the voltages and time. Stop it when the voltage has dropped to 3.2V.
4) Calculate the amount of average current over the period. The AH is the time period in hours times the average current.
 

So I should expect about 50 % ... 10 % of the advertised capacity only?
Click to expand...
huh ... yes.

And when it's under 30 %, you get a refund automatically, is there any law on this?
Click to expand...
there is no law on this. when I measured less than 30% of advertized capacity, I make a claim saying it's not the real product it's easy on ebay or paypal, and dx is really listening their customers. then I got a refund proportionnal to the real capacity of the battery it worked all the time.

"people nerver measure the battery capacity, they simply don't have the instrument for that"
could you describe how to do it?
Click to expand...
the two upper posters gave good methods to measure the capacity of liion batteries. people buy battery to replace another battery that failed, it's quite normal for lithium batteries to fail after 3-5 years of use. people just put the new battery in the apparel and if it's not totally dead they dont notice the battery has a smaller capacity because they already used a long used quite defective battery before they buy a "new" one. some rare guys like me measure the battery as soon as they arrive because I have a dedicated instrument here only to do that ...
 

Do you think that these cheap eBay batteries are old, heavily used? Or what is the cause of the small capacity?
 

ArminVanBuuren said:
Do you think that these cheap E-Bay batteries are old, heavily used? Or what is the cause of the small capacity?
Click to expand...
Didn't you see the video about fake batteries that I posted? Instead of expensive Lithium, the cheap fake battery had flour. Other cheap batteries sold on E-Bay are old and are worn out.

Buy name brand batteries from a REAL battery distributor.
 

Audioguru said:
Didn't you see the video about fake batteries that I posted? Instead of expensive Lithium, the cheap fake battery had flour. Other cheap batteries sold on E-Bay are old and are worn out.

Buy name brand batteries from a REAL battery distributor.
Click to expand...

I do not understand 'worn out' completely. So once they really used to be 6000 mAh, but they have gone through so many cycles that now they have only less than 2500 mAh?
 

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