I have a 2-cell battery charger for my 18650s (Zebralight). Do these chargers work in series or something (I'm obviously not an EE)? Often I'll have one completely drained battery and the other only partly discharged -maybe an hour's use. It seems that, depending on which slot I put the two batteries, the charger will turn green almost at once, maybe 5 minutes - telling me the good battery got topped off but I doubt the spent one can be recharged that fast. If I switch the battery positions, the red charging light remains on for 45 minutes or whatever...which would appear to say that both batteries are topped off. Is this common? Do I need to mark a full/empty on my charger? Is it okay to recharge a drained and a nearly-full battery at the same time?
This, btw, is why I like to standardize on AAs - I understand them! Thanks.