Charger Cytac CY-015
This charger is a dual channel LiIon charger.
The charger has a connector for the mains lead and is sold with different mains leads depending on country. The mains supply can be from 100 to 240 VAC and 50 to 60 Hz.
It can also be connected to a 12 volt source, i.e. a car.
There is two leds, they are red when voltage is between 0.5 and 4.2 volt else they are green. This means that the led will be green if a battery with to low voltage is placed in the charger!
The charger can handle up to 68 mm long batteries, this does not include all brands of protected 18650 batteries (See my 18650 LiIon comparison for length of different brands). The slider works very well on this charger, it has good connection for any battery length from 34 mm to 68 mm.
Below 0.5 volt there is no charger current.
Between 0.5 volt and 4.25 volt the charge current is on, see curve.
The charger does never turn the charging current off.
When charger is disconnected from power, but with a battery in, it will draw up to 2mA from the battery.
With two batteries the charging current is reduced, how much depends on actual charge state of the two batteries.
The charging curve looks mostly like a constant voltage with a series resistor (4.24 volt, 0.8 ohm). The yellow line marks where the led changed from red (charge) to green (done), but as can be seen the current is not turned off. With this type of charger it is strongly recommended to remove the battery when the led changes to green. With nearly 7 hours to charge the battery, it is not a very fast charger.
With a 16340 battery the charger is much faster, especially with this old battery with reduced capacity.
The charger does not follow the recommended charge procedure for LiIon batteries, but it does charge to 4.2 volt and a bit above if the battery is not removed. It takes a long time to charge 18650 batteries, batteries with less capacity will be charged faster, but nowhere near optimal speed.
The charger can be used, but will reduce the lifetime of the batteries, if the batteries are not removed when the led changes to green.
Here is an explanation on how I did the above charge curves: How do I test a charger