Li-Ion Charger charges two 18 V batteries in 60 minutes.

Suitable for jobsites running multiple Makita 18 V batteries, Rapid Optimum 4-Port Charger, Model DC18SF, is engineered with 2 controllers for faster charging than models with single controller. During charging process, charger communicates with computer chip inside each battery to monitor current, voltage, and temperature. ENERGY STAR

[source: http://news.thomasnet.com/fullstory/Li-Ion-Charger-charges-two-18-V-batteries-in-60-minutes-20011711]