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How to Replace Rectifiers in Old Battery Chargers

Rechargeable batteries require periodic recharging to keep the batteries in good working order. Over time -- whether such a battery is used or not -- the battery electrolyte begins to combine with the metal electrodes inside the battery. This process impedes the battery's ability to produce electrical power. To reverse this harmful electrochemical process, direct current (DC) power must be applied across the battery's terminals to rejuvenate the electrodes. Because most battery chargers plug into a wall outlet, these chargers contain an electronic device called a rectifier. This rectifier converts the alternating current (AC) power from the wall outlet into the DC power the battery requires for the recharging process. If the rectifier has been exposed to extreme heat or power surges, the rectifier may stop working and the battery charger will not provide DC power to the battery.

Things You'll Need

Battery charger
Screwdriver
Wire cutters
White electrical tape
Permanent marker
Rectifier block
Soldering iron
Electronic solder

Instructions

- 1
  Open the battery charger case by removing the case screws. Ensure that the battery charger is turned off and is not plugged into a wall outlet. Remove the battery case cover.
- 2
  Locate the rectifier in the battery charger case. This component often looks like a rectangular block and will have four labeled terminals. Two of these labels are either "AC" or "~"; the remaining labels will be "+" and "-".
- 3
  Cut the wires leading to the rectifier installed in the battery charger. Cut a piece of tape for each wire and label the wire as to its former location on the rectifier. Use the wire cutters to strip 1/2 inch of insulation from the ends of each of these wires.
- 4
  Remove the old rectifier from the battery charger and dispose of it accordingly. Install the new rectifier into the battery charger.
- 5
  Place the end of the "+" wire on the rectifier terminal labeled with a "+" symbol. Melt a small drop of solder to the terminal and the wire. Smooth out the soldered joint with the tip of the soldering iron until the joint is shiny and free of lumps.
- 6
  Place the end of the "-" wire on the rectifier terminal labeled with a "-" symbol. Solder the wire to the terminal.
- 7
  Place the first "AC" wire on one of the rectifier terminals labeled "AC." Solder this wire to the terminal. Place the remaining "AC" wire on the other "AC" rectifier terminal and solder this wire to the terminal.
- 8
  Replace the battery case cover. Insert the screws into the case holes and tighten each screw to close up the battery case.

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