Samsung INR18650-300 won't charge to 3000 mha, why please ?

[herbeapuce]

Hi.

My fiend bought some Samsung INR 18650-300 SDI 136. he says they are supposed to go to 3000mha and he can only get 2500.

his newly acquired charger is the BTY V407....
this should be the spec:

Output Voltage:	4.35±0.1%/4.2V±0.1%/1.48V±0.1% 9V(6F22)±0.1%
Input Voltage:	Type-C/MicroDC 5V 2A
Output Current:	Li-ion:1000mA*2(High)/500mA*4(Low)

what do you think the problem is ?

thank you

 

[Zak]

If you fill up your car, which has a 20 gallon gas tank, and it only takes 15 gallons, does that mean something is wrong?

 

[john61ct]

Samsung INR 18650-30Q is what those are (supposed to be) not 300.

They may be fakes, or factory QA rejects or secondhand. Link to source?

With what instrumentation and at what C-rate were the CC load discharge tests conducted?

 

[peter yetman]

Unless I'm mistaken the charger that you specify doesn't do a charge-dicharge-charge cycle.
As Zak says, you need to completely empty the tank before you can measure how much room there is for fuel.
P

 

[WalkIntoTheLight]

I have lots of those 30Q cells. Even when new, they usually only have about 2900mAh capacity. I suppose if you deep-discharge them down to about 2.5v, you might get closer to 3000mAh. Anyway, as others have said, you need to discharge from 4.2v down to somewhere around 2.75v to check capacity, around 500mA discharge rate.

If all you're using is the amount of charge you're putting into the cell, most chargers are inaccurate with that.

Or, yeah, they could be fakes. If you bought them from China, that probability goes up.

 

[herbeapuce]

thanks everyone for your help.

he's bringing them over here so I can check them on my ZanFlare C4 charger

he said he bought them from Banggood , so this could be a problem....

thank you.

 

[staticx57]

You really need to measure the discharge capacity. The 30Q is rated at 3000mAh when discharged from 4.2 Volts to 2.5 at 600mA.

 

[herbeapuce]

You really need to measure the discharge capacity. The 30Q is rated at 3000mAh when discharged from 4.2 Volts to 2.5 at 600mA.

thank you.
I set up a normal test on my charger at 500mA. From what I read on the manual it will fully charge the battery, then discharge, then fully charge again , and give the capacity. so this should give me the true mha at 500mA, right ? thanks

one more question plz : for a powerful flashlight torch , what is the acceptable resistance of a battery , from what to what is considered good plz ?

 

[WalkIntoTheLight]

thank you.
I set up a normal test on my charger at 500mA. From what I read on the manual it will fully charge the battery, then discharge, then fully charge again , and give the capacity. so this should give me the true mha at 500mA, right ? thanks

Correct. Though, not all chargers are perfect at measuring capacity. But, it should be close enough. Also, it might not discharge down to 2.5v. A lot of chargers will consider 2.8v to be fully discharged. So, they won't record the full capacity, but it should be close. There's not much capacity between 2.5v and 2.8v.

one more question plz : for a powerful flashlight torch , what is the acceptable resistance of a battery , from what to what is considered good plz ?

The 30Q spec sheet lists the internal resistance at less than 26 milliohms, using a 1kHz AC measurement. Note that chargers are typically awful at measuring internal resistance. Don't depend on the charger's absolute measurement. But you can compare it against other batteries to determine whether it's higher or lower.

 

[herbeapuce]

thank you very much.
Best regard
stef

 

[herbeapuce]

Strange ..this is the results I got.... ( I did choose 500 mA for the test)

I'm thinking rebranded 3500 mha ??....

Resistance measured with the charger runs from 19 to 27.

what are your thoughts on this plz? I would say 30Q no,, but still very good batteries, right ?

 

[WalkIntoTheLight]

Depending on how accurate your tester is, they might be rewrapped Panasonic 18650B's. Cheap cells, fine for moderately low-drain use, but they will sag horribly in a high-drain flashlight. Or maybe a cheap Chinese brand. In any case, at least they're not horrible fakes.

 

[herbeapuce]

they will sag horribly in a high-drain flashlight. Or maybe a cheap Chinese brand. In any case, at least they're not horrible fakes.

wouldn't the low resistence of the batteries (19 to 23) indicate it's adequate for high drain devices ? thanks

 

[peter yetman]

I think it's more a matter of low internal resistance being necessary if you are drawing a high current, rather than it being an indication of a high drain cell.
P

 

[WalkIntoTheLight]

wouldn't the low resistence of the batteries (19 to 23) indicate it's adequate for high drain devices ? thanks

You have no idea how accurate your charger is at measuring internal resistance. There's a 99% chance it's horribly inaccurate (like almost all chargers), so I wouldn't trust those measurements.

 

[herbeapuce]

ok.... thank you.

 

[sbj]

The ZanFlare C4 did quite well in HKJ's internal resistance measurement: https://lygte-info.dk/review/Review Charger Zanflare C4 UK.html
If you now take a few comparative measurements of known battery types that are not yet too old or used up, you can use them to sort these cells labeled as Samsung to a good or bad degree.

 

[herbeapuce]

thank you