Li-ion charging: Important to finish charge cycle?

[FsckCigs]

I know that it's OK (in fact preferable) to recharge Li-ions before they are "dead" but I can't seem to find a concise answer to the question of whether or not it's OK to take them off charge before they are fully charged. With the typical Li-ion declining-amperage charging scheme, so much of the charge cycle is dedicated to getting that last little bit of juice into them, it'd be awfully convenient in many cases to be able to take them off and use them rather than waiting another few hours for the
green light to come on. Is there risk in doing so (aside from missing out on those awesome fresh-batt 4.2v first few vapes)? I don't care so much about longetivity, as the batts are inexpensive enough..but as always, safety is of utmost concern. Anyone happen to know if this is an acceptable practice?

 

[RomanHelmet]

It is in fact desirable to not charge a li-ion battery to a full charge. Doing so stresses the battery. It is said that charging to less than the maximum voltage will substantially increase the usable lifetime of the battery, though I cannot recall the specific time period off the top of my head.

Source: Charing Lithium-Ion Batteries - Battery University

Li-ion does not need to be fully charged, as is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge, because high voltages stresses the battery. Choosing a lower voltage threshold, or eliminating the saturation charge altogether, prolongs battery life but this reduces the runtime. Since the consumer market promotes maximum runtime, these chargers go for maximum capacity rather than extended service life.

 

[stephpd]

I'd guess that if you stopped at the end of the constant currant portion of a cc/cv curve you'd get the longest life on a Li-ion battery. It wouldn't be fully charged but close enough for most applications.
Lithium Polymer battery and cells technical

Looking at that chart you'd only be getting ~4.1 volts instead of 4.2. The constant voltage portion is almost half the charge time and only increases the voltage .1 volts.

Cheaper chargers don't use this curve but an ever decreasing current charge until topped off.