56-674 CTEK Multi US 25000 Battery Charger. The CTEK Multi US 25000 is the Mac-Daddy of modern battery chargers. This FULLY AUTOMATIC - set it and forget it - This Rapid Charging Battery Charger does it all. A fully automatic 8 step process insures that your battery will always be maintained. This battery charger is so smart that it automatically regulates for temperature variations, diagnoses your battery and performs the correct charging process. The CTEK 25000 also has a supply mode, so you can get 12 Volt power where ever you are, even if it is not plugged in. Perfect for Winter Storage and taking your Corvette on the road.