Possible to detect used or old cells?

LED Flashlights – General Info 18650 Flashlights
1

Hi, i just ordered some cells from one Chinese store, don’t want to name them because it will look like that i i’m implying that they sell used or old cells.

What i would like to know, if there is a way to tell if the cell has been used physically, or with measurements? some damage of the vrapping? slight scratches on the buttom part from the chargers or anything? the cells i ordered are Panasonic 2900 mah PF.

Thanks!

2

No, I don’t think there is a general way.

However you could test the voltage. Usually li-ion cells are delivered partially charged, to around 3.75 volts. That is a charge that reduce the aging process when the battery is stored unused. If you ordered several cells of the same brand, and they have different voltages, then some of them may have been charged or discharged. Or they may just have been produced at different times…

You can also test the cells in an analyzing charger and verify that the capacity is OK. There is a group buy going on for an analyzing charger in another thread…

3

Thanks! so there is no other way sadly? :frowning:

You mean the Opus?

4

Yes, the Opus.

No, I don’t know any other ways.

5

If it is an unprotected or flattop battery, that has been used in a battery pack, it is usual possible to see the marks from the welded connections (Battery packs nearly always uses welded connections).

Except for that, you will have to compare performance to a known new battery.

6

Its Panasonic 18650PF green….2900 mah.

4x pieces…

Sorry i’m not really good with english, what is welded connections? :frowning:

7

gelötet bzw punktgeschweisst

if you speak German better than english :wink:

8

Sorry i don’t sadly :frowning:

9

The photo looks fine, the PF series is also fairly new, i.e. even if it used batteries they will be good.

A video about it:

10

Tank you so much!

So actually its the way to get the cells together for use in lower space laptops, or other applications in order to save some space?

The way they connect them should show some signs of wear on the top/bottom part of the cells if i understand it correctly?

Good to hear about PF being fresh model, and even if used it would be not bad i thought about it also :slight_smile:

11

Not only to save space, but also to get a very good connection with high reliability.

There will be some marks from the welding process, often you have to use a Dremel or similar tool to remove the welded strip completely.

12

Got it, thanks alot!