AN-1025: Using the EnerChip™ in Pulse Current Applications

©2009 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com

Doc AN-72-1025 Rev03

Page 2 of 8

Figure 2. EnerChip Discharge Capacity at Various Discharge Rates.

Battery Capacity Ratings

The rated discharge capacity of a battery is specified at a particular discharge rate. As the discharge rate

increases, there is a reduction in the available discharge capacity. The term known as the C-rate, specifies

the current that a battery will deliver when discharged to 100% depth-of-discharge in a period of one hour.

Conversely, battery capacity can be specified at a particular C-rate. For example, a cell’s capacity might be

rated at a discharge rate of C/4, or 0.25C, which means that it will deliver its rated capacity when completely

discharged over a 4-hour period. A cell with a rating of 1 Ampere-hour at a C/4 rate would be completely

discharged in 4 hours at a constant current of 250mA. At a higher discharge current, the discharge capacity

would be less than that available at the lower rate. Some cells are rated at low discharge rates of C/100 or

less. C-rate terminology is also applied to the charging rate of a cell.

The rated capacity of an EnerChip solid state battery is largely retained over a range of C-rates, as shown in

Figure 2. This allows the cell to be used in a variety of applications without sacrificing much discharge capacity

as the load currents vary across applications or from one operating condition to another within an application.

Maintaining performance over a broad range of C-rates makes a cell well suited for pulse current applications.

The EnerChip also has a favorable charge rate, with 30 minutes being a typical time for the EnerChip to reach

80% of its rated capacity.