Older phones were rather inelegant in their charging behavior; usually filling the battery to capacity and then switching to a trickle current to maintain the highest charge possible.
旧款的手机充电相当粗放，通常是电池充满后，充电器切换到涓流电流，来维持一个最高的电量。
2
Electricity, though, is pretty cheap, and filling a Leaf's 24 kilowatt-hour battery pack from empty should cost only about $2.64.
用电，却很便宜，把Leaf的24千瓦时的电池组从空充满只需2.64美元。
3
The charging of a condenser from a battery is not unlike the filling of tank from a reservoir.