Schumacher 12 Volt Battery Charger Instructions

by Chris Weis

Schumacher brand battery chargers are highly regarded by automotive repair professionals and home-based enthusiasts alike. The reputation this brand enjoys has been earned over the years by the reliable and capable character of the products. Many different models of chargers are available, with features that meet any needs anticipated. Small models can provide a slow charge to bring a battery up to par, while larger models can jump-start most cars and trucks in short order. The information and instructions provided in company produced literature is well researched and complete.

Ensure all vehicle electrical devices are turned off to avoid arcing at the battery. Observe battery polarity and determine if the negative post is grounded to the chassis. Negative-grounded systems are most common in passenger vehicles produced in recent times. Connect the positive battery charger lead to the positive, ungrounded battery post.

Unpainted studs or screws on the engine block are good grounding sites.

Connect the negative battery charger lead to a ground source on the car chassis or engine block. Avoid grounding to fuel lines or fuel delivery devices such as carburetors or throttle bodies. Clean any rust or corrosion from the grounding site selected with a wire brush, if necessary.

Plug in the AC power cord of the charger into a 120VAC electrical outlet and observe the charger indicator(s). Some models display battery voltage on a meter. The meter display can be analog or digital, depending on the model. Select the charging rate recommended by the manufacturer, for models equipped with this feature.

Monitor LED indicators on chargers that display an amber light for charging in progress. A green light will signify charging is complete. Unplug the AC power cord when charging is complete, or if a red LED illuminates. A red LED indicates internal battery problems. Seek professional testing to determine exact battery condition. Remove the charger leads after the power cord is unplugged.


  • check Check the battery acid level and add distilled water to the proper level before charging, if necessary. Check the sightglass on maintenance-free batteries for minmum acid content. If no liquid is visible in the sightglass, do not attempt charging the battery.


  • close Avoid contact with battery acid to prevent personal injury or property damage. Wear protective eyewear whenever working around batteries. Use plenty of water to flush away any errant acid. Read and heed all safety warnings on batteries. Make no attempt to use a charger that has been altered or damaged in any way. Do not alter or adapt the charger plug to fit an outlet not designed to accept the power cord plug. Keep open flames or lighted smoking materials away from the battery. Position the charger as far from the battery as the leads will allow to avoid overheating the charger or battery.

Items you will need


About the Author

Chris Weis is a freelance writer with hands-on experience in accident investigation, emergency vehicle operation and maintenance. He began his writing career writing curriculum and lectures in automotive mechanics at New York Technical Institute. Weis has contributed to "Florida" magazine and written procedure and safety guidelines for transportation concerns.

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