In an embedded system we have a lithium button cell to provide power for the real time clock IC and some RAM when external power is off.
Since such cells have a phenomenom called passivation, a chemical process covers the electrode if the cell is not loaded, you cannot assume it will just work after several years. This means that the cell should be "waked up" periodically to assure it will work when needed.
The dummy load, which is controlled by the processor, will give a load comparable to the max. rating of the battery. There is also a voltage comparator connected to the processor.
The question: Which pulse/pause pattern should be used? 10 - 20 sec. a day (one pulse), or 1 second every hour? Will an even shorter pulse every 5 or 10 min. work? The latter would give an alarm earlier when the cell fails. - And recognize a replaced cell faster. ;-)
Does anyone have experience with a such system? It may take some time to test. ;-))