One only way to find out for sure would be to use a DMM and see what happens when the "light turns green." That means stripping some wires on the chargers and putting the DMM in parallel with the charge circuit. It's also not a bad idea to repeat the test with the DMM in series with the charge circuit measuring current. Or use 2 DMMs at the same time.
Alternatively: There are other tests that you can do that would be less invasive and reveal a lot as well. If you have 2
batteries and a charger and a DMM you can do the following:
Charge up battery #1 until the light turns green.
Remove battery from charger and take a voltage measurement of the battery, record.
Charge battery #2 over-night.
Remove from charger and take a voltage measurement of battery #2, record.
Take a measurement of battery #1 again at this time, record.
Compare voltages. Now repeat all tests with the roles of the
batteries reversed to eliminate any variables.
If the cells that are being left on the charger for a longer period of time after the light turns green are rising to a higher voltage than those removed immediately after the light turns green, then there is a problem with the charge method.
Alternatively, if the cells being left on the charger for a long period of time after the light has turned green are not experiencing any voltage settling while on the charger, then they are being float charged at that voltage. This is also not ideal.
I have my suspicions that these chargers are probably NOT terminating the charge correctly. I don't own any ecigs that use their own proprietary
batteries/chargers because when I was researching ecigs, I couldn't not find any information to support that the chargers were properly terminating (or not properly terminating). In my world, li-ion chargers have no inalienable rights. They are guilty until proven innocent.
If you don't know for certain, you should ASSUME that the chargers don't terminate properly. Over the load haul, this can be dangerous.
Eric
