You replace the battery caps with the yellow caps. They are hooked together with cleear tubing.
![Image](http://i251.photobucket.com/albums/gg298/retiredhappy/batteryminder006.jpg)
There is a rubber cap on the end of the tube that attaches (next picture) to a piece of tubing with a pump just like a turkey baster.
![Image](http://i251.photobucket.com/albums/gg298/retiredhappy/batteryminder002.jpg)
The two tubes just snap together.
![Image](http://i251.photobucket.com/albums/gg298/retiredhappy/batteryminder003.jpg)
Last put one end of the tubing into a bottle of distilled water and pump. When you can't pump anymore the batteries (both of them) are full. Remove the tube piece with the pump and go your merry way.
![Image](http://i251.photobucket.com/albums/gg298/retiredhappy/batteryminder004.jpg)