[HKJ]

Charger CottonPickers 4.35 volt + DM



Cottonpickers makes a line of small single cell USB LiIon chargers. This is a special model for Samsung ICR18650-30A 4.35 volt cells.



The charger is supplied in a plastic bag with a simple hand written instruction sheet and two sets of charge leds, one set with magnets and one set with alligator clips and magnets. There is no cradle for batteries.



With magnetic leads can easily be attached to the ICR18650-30A cell.





The charger is not build into any kind of box, just sealed with silicon and adhesive rubber tape. This makes it a very compact charger, but the design is not exactly good looking. The charger has printed specification on the side of the led display.
The charger has a led sealed into the silicon, this will make the silicon opposite the usb connector glow red when charging.



This charger cannot be used for any standard LiIon battery, only for the Samsung ICR18650-30A 4.35 volt cells.



Measurements

Below 2.9 volt the charger will use a trickle current of 44-50 mA.
Between 2.9 volt and 4.35 volt the charger is applying regular charge current (See curve below).
The charger restarts charging at 4.25 volt
When the battery goes above 4.35 volt or the charge current stops, the charger will discharge with 15mA because the voltmeter is powered from the battery.
When charger is disconnected from power, but with a battery in, it will draw about 15 mA from the battery, again due to the voltmeter.



This charger only supports one battery type and for this reason there are only one test. It shows a nearly perfect CC/CV charger.



Conclusion

The charger is very close to a perfect CC/CV charging profile but can only be used for a single type of 18650 cell. The voltmeter is a nice function, making it easy to verify the cells voltage, but it has one disadvantage: it will discharger the cell a bit when charging is finished.
For people that wish to take advantage of the slightly higher voltage of the Samsung batteries this is the charger to get. To see how much extra capacity is gained with the higher voltage, see my 18650 LiIon comparison.



Notes

Here is an explanation on how I did the above charge curves: How do I test a charger