just a tip for anyone with cordless batteries which no longer hold charge. It is often possible to change the cells within the battery relatively cheaply.
If you can dismantle the faulty battery, inside you will normally find a sealed lead acid or gell cell battery. Shops like Maplin often sell direct replacements. I have changed a couple of my Dewalt 18v 2.4ah cells for less than £50 and now they are as good as new.
If you can't dismantle your battery, or you cannot find a direct replacement cell, toolnation often have genuine batteries at well below MRP.
Make sure if you do replace the cell it is a direct replacement in terms of type, voltage and size.