For laptops or other mobile devices, a battery charging arrangement wherein fast-charging and/or slow-charging is governed by something other than a fixed, immovable battery level threshold. Particularly, a variable threshold is broadly contemplated herein which may be governed by any of a very wide variety of conceivable factors, including (but by no means limited to) information relating to a user's schedule or calendar, especially as regards “free” time when a user is not using a computer. Accordingly, if there is a long uninterrupted period of computer “downtime” (i.e., when a user is not using the computer), the battery level threshold below which fast-charging takes place can be lower. By the same token, for short periods of computer downtime, this threshold can be higher. In this manner, fast-charging is reserved only for the most compelling, time-based circumstances.