CHOOSING RTC BACKUP POWER: Supercapacitor vs Battery?

CHOOSING RTC BACKUP POWER: Supercapacitor vs Battery?

Jetson AGX Xavier | Jetson Nano | Jetson TX2 NX | Jetson Xavier NX

26 April 2021
WHAT YOU WILL LEARN?

1- Advantages and disadvantages of supercapacitors

2- Advantages and disadvantages of batteries

3- Applications appropriate for each option

ENVIRONMENT

Hardware 1: MILBOARD - XV

Hardware 2: DSBOARD - NX2


There are two alternatives for secondary power supplies; batteries and supercapacitors. The latter one is getting more and more present in modern electronics. But is one simply better than the other or are there some tradeoffs that make each one suitable for different kinds of applications? We will approach this question in 6 different aspects.


1) ENVIRONMENT

Supercapacitors are made of carbon, aluminum and organic electrolyte, which makes them environment friendly. They do not have the disposal issues of batteries due to their non-chemical structure. Also, they have a higher lifetime than their rivals, which translates into lower waste generation.


2) ENERGY STORAGE CAPABILITY

While supercapacitors have the highest energy density of any capacitors, capacitors in general have very low energy storage capability. Batteries perform much better in this category. They have a much longer holdup time while supercapacitors are limited in comparison. 


3) LIFETIME

Batteries rely on chemical reactions to provide power. Once the electrolyte is used up, they need to be replaced. Supercapacitors don’t have this issue and have much longer lifetime.


4) COST

Supercapacitors initially cost higher than batteries. For this reason, many low-cost applications choose batteries over them. Things may turn around from a long-term perspective though, since batteries have shorter lifetime than supercapacitors.


5) SIZE & PRODUCTION

Supercapacitors are smaller in size compared to batteries (and holders), which is a big plus for dense boards. They also fit better in modern production techniques, allowing an easier assembly process. 


6) FAILURE

When batteries fail, they may harm the PCB or surrounding circuitry (outgassing, ignition, etc.) due to their chemical structure. Supercapacitors have open-circuit failure mode, which means they won’t cause any harm.


Batteries and supercapacitors; each have their own pros and cons. Batteries shine in applications where long holdup time and low initial cost are required while supercapacitors are preferred for being environment friendly, having longer lifetime, smaller size and safer failure mechanism. In ForeCR product family, we prefer to use supercapacitors as we feel they are more reliable and fit better to industrial grade applications.