Health warning, I'm not a battery expert, I have a fair amount of experience with lead-acid leisure batteries but here I am just parroting stuff I have looked up and made an effort to corroborate.
This article is about 10 years old and I can't speak for its accuracy, but it says that Li-ion batteries do not need to be "saturated" or fully cycled like NiCads and NiMH, in fact it's better if they aren't charged to 100%*** (and some chargers actually aim off for that, shutting off at a little less than maximum voltage).
Panasonic 18650 and similar cells are Lithium Nickel Manganese Cobalt Oxide type (NMC) if anybody wants to look them up.
Part of the difficulty here is not knowing for certain what the designed behaviour of a particular charger is.
The summary from the above-linked article:
Simple Guidelines for Charging Lithium-based Batteries
- Turn off the device or disconnect the load on charge to allow the current to drop unhindered during saturation. A parasitic load confuses the charger. [unlikely to apply to an e-bike].
- Charge at a moderate temperature. Do not charge at freezing temperature.
- Lithium-ion does not need to be fully charged; a partial charge is better.
- Not all chargers apply a full topping charge and the battery may not be fully charged when the “ready” signal appears; a 100 percent charge on a fuel gauge may be a lie.
- Discontinue using charger and/or battery if the battery gets excessively warm.
***EDIT It has been pointed out to me that not charging fully could mess up the charge balancing of the cell groups as this commonly takes place after the charge process is otherwise complete. I did say I'm not an expert. Perhaps the statrting point should be to read the manuals, although neither of my Bosch battery or charger manuals is explicit on this point.
- Apply some charge to an empty battery before storing (40–50 percent SoC is ideal)