Choosing the correct power source is critical, as mentioned earlier. The following table provides a summary comparison of different components in a system to be considered when picking the correct power source:
|
Category |
Li-ion Battery |
Supercap |
|
Energy density |
200 Wh/kg |
8-10 Wh/kg |
|
Charge-discharge cycles |
Capacity drops after 100 to 1,000 cycles |
Nearly infinite |
|
Charge-discharge time |
1 to 10 hours |
Milliseconds to seconds |
|
Operational temperature |
-20oC to +65oC |
-40 degrees Celcius to +85 degrees Celsius |
|
Operational voltage |
1.2 V to 4.2 V |
1 V to 3 V |
|
Power delivery |
Constant voltage over time |
Linear or exponential decay |
|
Charge rate |
(Very slow) 40 C/x |
(Very fast) 1,500 C/x |
|
Operational life |
0.5 to 5 years |
5 to 20 years |
|
Form factor |
Very small |
Large |
|
Cost ($/kWh) |
Low ($250 to $1000) |
High ($10,000) |