"To get a better idea about how it will work in a flashlight, I need a load on the battery, here I am using a 1ohm resistor. The battery still maintains voltage enough to drive a flashlight. The resistor must be at least 3 watt, but a resistor rated for a higher wattage (i.e. 10 watt) is much better, because it will stay cool.
Next battery is a LiIon 18650 battery, this requires the 20V range, the battery has 4.17 volt. For a LiIon this means that it just about fully charged. The voltages for a LiIon must be measured without load and are: Fully charged 4.2V, empty 3.6V
When getting a new LiIon charger it can be a good idea to check the voltage, on the cells, when they are removed from the charger, they must not be above 4.3V, it is much better if they are at 4.2V."
Could I ask why a LiIon must be measured without load whereas an Alkaline or NiMH needs to be measured with load in order to gauge the energy level of the battery? What happens if you measure a LiIon with load?