C-TEK MXS3.8 Battery Charger 14.4/14.7v 3.8A MX3.8 Charger is well suited for Everyday Use. If you have a vehicle battery that is giving less than optimal performance, the MXS3.8 charger is a great way to test that it’s salvageable and extend the battery life. If you’re away for a while, connect it and forget it.