Seems to be a Sanyo cell but no URxxxxxx stamped on wrapping.
Red Wrap, Red ring
F stamped at the bottom
Up to 2250 mAh after testing
Note: Thanks, but we can't do anything with them without a model number.
Submitting LG 18650 S4 cells
Refrence : LGAAS41865
Capacity : 2200 mAh
Max charge : 4A
Max discharge : 4.4A
Cut-offs : 2.75 / 4.2
The only found link : https://wholesaler.alibaba.com/product-detail/China-supplier-LG-18650-battery-S4_60551215285.html
Seems to be a Sanyo cell.
The reference is "engraved in the plastic wrap".
You can read it with a strong light, playing with it at the surface of the cell.
You may read something starting with UR1865...
The storage voltage is 3.7v indeed. There is no saturation as the charging curve is still is constant current mode for this voltage.
From my observation of the O.pus charger, it start to ramp down the current from 4.05v to slowly decrease the power sent to the cell.
The cutoff occurs when the...
Maybe only the 2 on the right of the 1st picture worth having a look.
In case you are going to salvage them, I suggest to replace the wrapping in order to check the body... but there no high expectation from my point of view
As far as I am testing some cells (just beginning with a few hundreds), here my comments
- Samsung 26F are quite good. Not that much failed
- LG cells are difficult to read from part number and spot welding is generally stronger that makes the tear down difficult. In average more weak cells
Just in case this can help, the pinout of laptop batteries seems more or less standardized.
Here some info throgh a video :
They are using a laptop battery tester RFNT3 which is a bit expensive (~250 bucks)
2500 mah rated with 5000 mah max discharge rate according to https://urun.gittigidiyor.com/bilgisayar-tablet/lg-cp2-18650-3-7v-2500-mah-sarjli-lityum-pil-304830387#product-detail
Product name 18650 CP2
Purple Cell Wrapper
White Insulator Ring
16650 Form Factor
Using digital pot such as Analog Device AD5161 seems a working solution to set the current by software.
An Arduino lib for that one I shared months ago : https://github.com/sosandroid/AnalogDevice_AD5161
But indeed this will weigth more into the BOM
LG cell part number reading
This may help others and provide an easier way to find datasheet. As per my readings yesturday using GTranslate on chinese forums, here the sum-up of my findings
A cell part number is a reference of 10 to 11 characters for LG. This is built as the concattenation of...
LG AA MF1 1865
AA: 1 or 2 symbol, AA Assembly site of Nanjing
MF1 : model
1865 : 18650 form factor
This is the same as LGDAMF11865 & LGEAMF11865
Got it from that forum http://www.ddclm.com/bbs/thread-497830-1-1.html