CEN-TECH 2/10/40/200 Amp, 6/12V Automatic Battery Charger with Engine Jump Start

The terms “Dead Battery” and “Bad Battery” are often loosely used to describe various battery issues. Understanding the differences between a dead battery and a bad battery could help address the battery issue appropriately.

A dead battery can often be brought back to a healthy state. As an example, a dead car battery will not start a vehicle when its voltage is below 12V.

Bad batteries cannot be brought back to a healthy state. Signs of a bad battery often include the inability to hold charge or charge to full capacity, the battery voltage immediately dropping as soon as the battery charger is disconnected from the battery, and the battery voltage being very low. Additional signs of a bad battery include when the battery voltage can be quickly boosted to full capacity level or when the battery voltage and/or the battery charger current fluctuates throughout the charging process.

Understanding the differences between a battery charger and a battery maintainer can help you choose the correct tool for your application.

You should use a Battery Maintainer to help keep batteries topped off when they are stored for an extended period. A Battery Maintainer may be used to top off lawn mowers and motorcycle batteries in the winter and show car batteries while in storage. When using a Battery Maintainer, always disconnect the battery from the vehicle or equipment it is intended to power. This will prevent additional current drawn by the vehicle or equipment from straining the Battery Maintainer.

You should use a Battery Charger to charge a dead battery. Certain Battery Chargers have diagnostic features such as battery testing, charging system testing, and battery reconditioning. Certain models may provide a higher current to boost or start an engine.

If you are experiencing issues with your Battery Charger, use a Harbor Freight Tools battery tester to check your battery’s health. If you need to charge the battery, make sure that the voltage of the charger matches the voltage of the battery you are charging.

A battery’s voltage will differ from at the beginning, during, and after charging. This is a normal part of the charging experience. For example, a healthy and fully charged 12.7V battery can reach 13.4V during charging.

Harbor Freight Tools’s battery chargers have basic “bad battery detection” while charging. They will not charge a “bad” or defective battery. Do not force charge a bad battery. We recommend performing a battery test with a tester that can provide the battery’s state of health such as the VIKING 12V Digital Battery and System Tester.

For certain chargers, the Engine Start feature may not be the equivalent to a jump starter. The Engine Start feature is a function that quickly supplies a large amount of current, usually from 50A to 300A depending on the charger model, after which it will then require a “cool down time”.

To increase the chance of successfully starting an engine:

1. Check your battery with a battery tester to ensure your battery is not bad. Do not use an engine start feature if you have a bad battery.
2. If the battery is not bad, we recommended to first boost charge the battery with 25A or 40A before using the Engine Start function.

Instructions for proper use, maintenance, and care are included in the Owner’s Manual. Below are a few things to keep in mind to make the best use of your battery charger.

1. Never pull the power cable to unplug the charger or the maintainer. Instead, unplug from the wall by pulling the plug.
2. Inspect the cables for damage. Never use a charger with a damaged cable.
3. Inspect and clean the air vents to ensure appropriate cooling and venting. Always unplug and disconnect all the cables before and during cleaning.