The battery I'll be using for this demonstration is from a DeWalt 14.4 volt cordless drill. A replacement battery from Lowe's is $74.00 dollars. The best price I found online was $68.11, plus shipping, and that would run the price beyond Lowe's price. That's reason enough to rebuilt the battery pack myself. I ordered 11, sub C, NiCad batteries, including shipping for $32.17. That's a savings of $41.73.  Time spent replacing the rechargeable batteries was a little over an hour. Not bad, huh? Be sure to purchase the correct batteries for your pack.

To solder the tabs in place, I used an electric, 150/230 watt soldering iron. An iron needs to be hot enough to melt the solder quickly and get off the battery, otherwise holding an iron on  a battery too long could ruin a new battery.

I was lucky the pack was assemble with screws. Many battery packs are glued or melted together, but not impossible to open.

First remove the eight screws holding the case together; you'll need a small Torx screwdriver. With a flat screwdriver, carefully insert it at the  seam of the top and bottom to separate them. In the neck where the battery packs contact terminals are located, push down with a small piece of wood to remove the top.

Remove the old batteries from the case. Now is a good time to make a sketch of the batteries, first the top, then the bottom, showing in your drawing the positive and negative connections. Don't depend on your memory because it's easy  to get mixed up.

The gadget on top is not a battery. It's a regulator to prevent over charging. With a pocket knife or small screwdriver pry loose from the battery the tab that's connected to     the regulator. Turn the pack over and remove the insulator that's covering the bottom side of the pack. Take your time removing the insulator because it can be reused. I damaged mine requiring me to make one from a piece of card stock.

After you have the insulator off, remove the positive connection from the battery to the regulator and set the regulator aside for later use.

It's a good idea to wrap tape around a the old pack to hold them together while you remove the tabs. If you purchase batteries with tabs, the rebuilding is much easier. I didn't want to pay the extra price for tabs.

With the top of the old pack face up, carefully remove the insulator and remove all the tabs from the batteries top and bottom. On a flat metal surface place all the tabs and hammer them flat.

Place all eleven batteries in the bottom part of the case in the same order the old            batteries were removed. That is, with the positive and negative up or down. This will assure the batteries will fit inside the case after soldering all the tabs in place if you purchased batteries with tabs or without. First do the top of the pack, then turn the new batteries over and solder the tabs as they were arranged on the bottom of the old pack.

With the batteries in the case and in the upward position, glue the top insulator in place, and now, solder the regulator negative tab to the negative battery bottom as shown here.  Test fit the battery case top. For attaching the insulators to the top and bottom I used clear silicone. It holds well and easier to remove.

Remove the batteries from the case, solder the positive connector from the regulator to the correct battery positive end. Glue the bottom pack insulator in     place.

Put the new batteries in the bottom part of the case and slide the top piece of the case in  place. Install the screws and place the rebuilt battery pack on its' charger.

   Now you have a rebuilt battery pack for less than half the cost of a new pack.