The Digitrax command station, DCS100, contains a CMOS battery to remember settings while the power is off. Normally, the unit will beep seven times to indicate that the battery needs to be replaced. I was having a problem with one of my throttles, and it was suggested, considering my system was at least 9 years old at the time, that the battery needed to be replaced. This photo essay shows how to do that. The unit has two screws on top that need to be removed.
There are also two screws on the bottom of the case that need to be removed. According to the Digitrax manual, doing this does not void the warranty.
Before the case cover can be removed, the plug in the front needs to be removed. It is on there pretty tight, but you can just pull it off away from the unit. A slight wiggle (not too much) left to right will do the trick.
The top circuit board has two battery holders. One is empty and the other has the battery that needs to be replaced. To preserve what is in the unit's memory, the instructions say to insert a new battery in the empty battery holder first.
The DCS100 requires a single CR 2032 cell battery. You can find these at any electronics or grocery store.
First, insert the new battery in the empty battery holder. To do that, lift up the contact arm and slide the battery into its slot. Be sure to pay attention to the polarity; simply match it to the old one.
Now you can safely remove the old battery. I used a pair of curved tweezers to be able to get a hold of the battery while my other hand held the contact arm up.
While the unit was open, I was looking through the manual and found out that you can adjust the output voltage to the tracks. This is done via the yellow potentiometer highlighted in the photo below. I didn't need to do this, but I wanted to point it out in case you are looking for how to do that.