Hi, first off I'd like to say happy new years!
Yes...you can put a IMR battery back on the charger after only an hour of use....some chargers will not start a charge cycle though unless your battery is below 4.1 volts (ie...you take three drags and put it on the charger then the charger will notice the battery is still nearly fully charged and will not start a charge cycle because of built in overcharge protection in the charger)
IMR batteries are not supposed to have a memory and it is actually better for the battery and should have a longer life if you do not drain it fully. only draining your batteries to around 3.5-3.7 volts can extend a good batteries life because you are not putting threw the stress off a full cycle (ie draining the battery fully down to 3 volts and then recharging to full.) The more charge cycles you put your battery threw it increases the internal resistance of the cell causing it to loose some of it's capacity over the batteries life....by only partially draining the cell and recharging it you put less stress on the cell causing this process to take longer extending the batteries life. Also, you don't have to persay, but it is a good idea to let the battery rest for 15 minutes or so before charging and again for the same amount of time after charging before using it again. I know it sounds like a pain but letting the battery rest before/after charging helps let the battery "rest" and settle and can contribute to longer battery life from again putting less stress on it.
for safety I would not leave the battery on the charger all night...even if the charger has built in protection like a nitecore anything can happen. most likely it will not fail but if for some reason it does and your battery overcharges in your sleep it can pop and leak or even worse catch fire. No battery should be left charging unattended, not just the IMR's we use, but any battery period. Also, for the health of the battery you don't want to drain it below 3 volts...some can be drained down to 2.5-2.75 but that is the rating and not the end all line in stone....besides...draining a battery that low would be a horrible vape on a mech unless you like weak vapor. Hope some of this helps and happy vaping and cheers!
