Battery chargers have come a long way. The triple-mode, seven-stage BikeMaster ChargeMaster 365TD ($90), for example, analyzes the condition of any 12-volt battery and its connection polarity, while also recovering mildly and/or heavily discharged batteries, even in freezing conditions. Plus, it can be connected for months or even years at a stretch. A backlit LCD shows the real-time charging rate, including voltage and amperage. A wall bracket and extra-long cables are supplied.