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Battery Tender Junior Instructions

by Arthur Barnhouse

Battery Tender Jr. is an automatic battery charger and battery maintenance device all in one. Because it charges at a rate of only 0.75 amps per hour, the Battery Tender Jr. is best used as a trickle charger. This means that the battery is charged slowly over a long period of time -- usually several hours for a typical 12-volt car battery and up to several days for a marine or deep cycle battery. Fortunately, operating a Battery Tender Jr. is fairly easy, even for those unaccustomed to the use of battery chargers.

Step 1

Slip on a heavy pair of work gloves and some form of eye protection, such as goggles or safety glasses. Batteries contain acid, which is capable of producing severe burns and eye damage. If the battery is in the vehicle, detach any guards, shields or covers that obscure the battery terminals.

Step 2

Place the Battery Tender Jr. in a safe location as far away from the battery as the cables will allow. If the battery is still in a vehicle, ensure all cables are away from any moving parts, such as hinges or fan blades.

Step 3

Attach the positive (red) clip or ring of the Battery Tender Jr. to the positive battery terminal. For a battery still in the vehicle, attach the negative (black) clip or ring to the engine block or solid portion of the frame. Never connect to fuel lines, sheet metal or any part of a carburetor. For a battery removed from the vehicle, connect the positive clip as normal. Then attach a 24-inch battery extension cable to the negative terminal. You must then connect the extension cable to the Battery Tender's negative clip/ring.

Step 4

Connect the Battery Tender Jr.'s power cord to an AC power outlet. If necessary, use a quality extension cord. Unless you are using the Tender Jr. to maintain a fully charged battery, the red indicator light should come on. This lets you know the connections are good and the battery is charging.

Step 5

Allow the battery time to charge. Again, at a rate of 0.75 amps every hour, the exact time to achieve a full charge will vary. Indicator lights will show the progress of the charge. When the green light begins to flash, the battery is approximately 80-percent charged. A steady green light indicates that the battery has completed a full charge and that the Battery Tender Jr. has entered a battery maintenance mode.

Disconnect the Battery Tender Jr. from the electrical outlet once the battery has a full charge. Then unhook the clips/rings from the terminals. If you wish to maintain the battery's charge, you may allow the Battery Tender Jr. to remain connected to the battery.


  • Clean the battery terminals if necessary. You may use a wire brush or terminal cleaning brush. Corroded or dirty terminals may interfere with the charging of the battery. If you have a traditional flooded battery, check the fluid/electrolyte level within the battery. If the level is low, refill with distilled water. Do not, however, overfill the battery. A battery that is low on electrolytes will not charge correctly.


  • Keep all open flames away from the battery. Never charge a battery in a poorly ventilated area. Also never disassemble your Battery Tender Jr. If it malfunctions, take it to a qualified technician.

Items you will need

  • 24-inch battery extension cable (for batteries that have been removed from the vehicle only)
  • Eye protection
  • Work gloves

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