Higher than stated capacity? Possible or a testing error

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Bryn

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Hi All

Just processing a batch of salvaged SamsungICR18650-20B cells and got a weird result.

According to the datasheet these cells have an initialcapacity of 2000mAh, however I've just completed a NOR Test on 3 of thesecells in a Liito Kala Lii-500 and it reports 2160/2110/2098 mAh respectively.

The cells appear fine, I suspect the source battery was unused, and the cellshave respectable 25-44 mR internal resistances

Is it possible that the cells emerged from the factory with capacity> than the stated2000mAh or is the Lii-500 on the blink?


Cheers!
 
That's sounds about right. Those type of testers can show higher and the amount is not bad
 
Bryn said:
Hi All

Just processing a batch of salvaged SamsungICR18650-20B cells and got a weird result.

According to the datasheet these cells have an initialcapacity of 2000mAh, however I've just completed a NOR Test on 3 of thesecells in a Liito Kala Lii-500 and it reports 2160/2110/2098 mAh respectively.

The cells appear fine, I suspect the source battery was unused, and the cellshave respectable 25-44 mR internal resistances

Is it possible that the cells emerged from the factory with capacity> than the stated2000mAh or is the Lii-500 on the blink?


Cheers!
Click to expand...

I really like the Lii-500. I'm using 2 of them for all of my cell testing.

It may be that the discharge testing is different to how the manufacturer reached its rated capacity. The Lii-500 has a max discharge rate of 500ma according to the specs and they discharge down to 2.8v. (The display is a bit confusing though since NOR test 1000 is an option, but I think that's just the max charge rate)

It's possible that if they were tested at 1a discharge and down to 3v for example, they'd be closer to the rated value or a bit under it.

I saw the max discharge rate of 500ma in the Banggood sales listing after I bought mine. It doesn't really bother me though since I'm building 100p packs and just wanting to get the total capacity near the same. I think it's a bigger problem if you are doing capacity testing with a range of different charger models. (even the same model charger has some variation).

Edit, this is the review which caused me to look for these chargers

http://lygte-info.dk/review/Review Charger LiitoKala Lii-500 UK.html

I certainly didn't read all of it :) There is a conclusion paragraph at the end.
 
That's great, :)thanks guys.


Fingers crossed that the rest of the batch are as good

neilmc said:
Bryn said:
Hi All

Just processing a batch of salvaged SamsungICR18650-20B cells and got a weird result.

According to the datasheet these cells have an initialcapacity of 2000mAh, however I've just completed a NOR Test on 3 of thesecells in a Liito Kala Lii-500 and it reports 2160/2110/2098 mAh respectively.

The cells appear fine, I suspect the source battery was unused, and the cellshave respectable 25-44 mR internal resistances

Is it possible that the cells emerged from the factory with capacity> than the stated2000mAh or is the Lii-500 on the blink?


Cheers!
Click to expand...

I really like the Lii-500. I'm using 2 of them for all of my cell testing.

It may be that the discharge testing is different to how the manufacturer reached its rated capacity. The Lii-500 has a max discharge rate of 500ma according to the specs and they discharge down to 2.8v. (The display is a bit confusing though since NOR test 1000 is an option, but I think that's just the max charge rate)

It's possible that if they were tested at 1a discharge and down to 3v for example, they'd be closer to the rated value or a bit under it.

I saw the max discharge rate of 500ma in the Banggood sales listing after I bought mine. It doesn't really bother me though since I'm building 100p packs and just wanting to get the total capacity near the same. I think it's a bigger problem if you are doing capacity testing with a range of different charger models. (even the same model charger has some variation).

Edit, this is the review which caused me to look for these chargers

http://lygte-info.dk/review/Review Charger LiitoKala Lii-500 UK.html

I certainly didn't read all of it :) There is a conclusion paragraph at the end.
Click to expand...

I saw that review too, made good geeky reading
 
Reading the SDI from Samsung, You can get 2100 mAh discharging at 0.2C at 60C..
I would not go that high though :)

ChrisD
 
Bryn said:
Just processing a batch of salvaged SamsungICR18650-20B cells and got a weird result.

According to the datasheet these cells have an initialcapacity of 2000mAh, however I've just completed a NOR Test on 3 of thesecells in a Liito Kala Lii-500 and it reports 2160/2110/2098 mAh respectively.
...
Click to expand...

Another thing to remember is production variation or tolerances.
The datasheet claim for capacity is going to be the mimimum you should expect (under their statedtest conditions). Not exactly this much and no more, no less.
And I doubt any manufacturer actually tests100% of production through a full charge/discharge cycle...
 
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