How to Replace the Battery in a Sonic Complete

As the first sonic toothbrush offered by Oral-B, the Sonic Complete features various brushing modes: a 30-second interval professional timer, power up to 45,000 brush strokes per minute and a rechargeable battery. The battery charges through the base, which is plugged into a regular AC outlet. If you fully charge the battery, the Sonic Complete will hold the charge for about two weeks until the rechargeable battery dies. At this point, you can either throw your Sonic toothbrush away or replace the battery.

Things You'll Need

• 2 NiMH rechargeable batteries
• Soldering gun
• Solder
• Insulating tape
• Needle-nose pliers
• Small wire cutters

Show More

Instructions

• 1

  Buy two new NiMH rechargeable batteries with soldering tabs. These are available at online stores such as Battery Price and Monster Marketplace. You need two battery cells of the same size that fit into the toothbrush, like the GP100AFH.

• 2

  Solder the batteries by placing them end-to-end, negative to positive. Extend the tabs and apply a small amount of solder to join them in the middle. Wrap the batteries afterward with tape to protect the middle joint, leaving the ends bare.

• 3

  Take apart the toothbrush. Unlock the bottom by pressing it against the small protrusion located at the back of the charger. With a firm grip, turn the toothbrush counterclockwise until you feel it pop. The bottom will spring loose -- remove it carefully so as not to damage the copper wires.

• 4

  Push gently on the steel rod to disengage the old battery and circuit board from the exterior casing. Remove the old battery. Use the pliers to pry the soldered tab away from the battery and the wire cutters to cut the solder. Cut as close to the battery as possible to leave contact points for the new batteries.

• 5

  Put in the new batteries, leading with the positive end. The negative end connects with the circuit board at the bottom of the toothbrush. Bend the old soldering tab to the tab at the bottom of the new battery to create a contact point. Your Sonic Complete should work with only a contact point; alternatively, you can solder the new battery tab to the circuit board.

• 6

  Reassemble the toothbrush by carefully reinserting the circuit board and batteries back inside the outer casing. Turn the toothbrush upside to reattach the bottom. Tighten by pressing the bottom against the protrusion at the back of the charger and turning clockwise.