Super Capacitor verses Battery Bank


JohnD. <john7damato@...>
 

1. Why would you use a super capacitor verses a battery bank? 

2. How do I detrrmine the size of the super caoacitor?

I am at the begining of the planning and trying to understand this concept. Do I use a super capacitor stand alone or with my batteries?

Thank you.

JD.


Joachim Saupe
 

Hello John,
Super Capacitors can be charged and discharged quickly with a LOT of current.
Batteries have to be charged more slowly with lower current and batteries also should be limited in it's discharge otherwise the life of a battery is drastically reduced.

For Solar systems there is no sense at this point in time to use Super Capacitors because you don't have these high charge and discharge currents.
Now in automobiles you want a fast charge and you also want to be able  to use a LOT of current for short acceleration bursts. In that application Super Capacitors make sense.

Joachim

“The test of our progress is not whether we add more to the abundance of those who have much; it is whether we provide enough for those who have too little”
Franklin D. Roosevelt



On Monday, June 28, 2021, 11:58:58 AM CDT, JohnD. <john7damato@...> wrote:


1. Why would you use a super capacitor verses a battery bank? 

2. How do I detrrmine the size of the super caoacitor?

I am at the begining of the planning and trying to understand this concept. Do I use a super capacitor stand alone or with my batteries?

Thank you.

JD.


Mellen West
 

My view of capacitors is they a jump starters for electrical equipment.

 

 

From: main@NTREG.groups.io <main@NTREG.groups.io> On Behalf Of Joachim Saupe via groups.io
Sent: Monday, 28 June, 2021 3:24 PM
To: main@NTREG.groups.io
Subject: Re: [NTREG] Super Capacitor verses Battery Bank

 

Hello John,

Super Capacitors can be charged and discharged quickly with a LOT of current.

Batteries have to be charged more slowly with lower current and batteries also should be limited in it's discharge otherwise the life of a battery is drastically reduced.

 

For Solar systems there is no sense at this point in time to use Super Capacitors because you don't have these high charge and discharge currents.

Now in automobiles you want a fast charge and you also want to be able  to use a LOT of current for short acceleration bursts. In that application Super Capacitors make sense.

 

Joachim

 

“The test of our progress is not whether we add more to the abundance of those who have much; it is whether we provide enough for those who have too little”

Franklin D. Roosevelt

 

 

 

On Monday, June 28, 2021, 11:58:58 AM CDT, JohnD. <john7damato@...> wrote:

 

 

1. Why would you use a super capacitor verses a battery bank? 

2. How do I detrrmine the size of the super caoacitor?

I am at the begining of the planning and trying to understand this concept. Do I use a super capacitor stand alone or with my batteries?

Thank you.

JD.


Skip Cave
 

First the good news: A typical super capacitor can support as many as a million charge/discharge cycles before its energy storage capacity is degraded. A typical chemical battery (e.g. Li-ion) can last for a few thousand charge/discharge cycles before its energy storage capacity diminishes fairly rapidly.  Also, a super capacitor can be charged and discharged orders of magnitude faster than a chemical battery (assuming you have the current capacity to charge it that fast, a non-trivial assumption), and if you really need that much energy dispensed in a short time (like a few seconds).  

Now the bad news: Energy storage density of current super capacitors is on average of around 28 Watt-hour per kilogram (Wh/kg) whereas a Li-ion battery can store about 200Wh/kg. So the supercapacitor storage system volumes will be  more than 7 times as large as the equivalent Li-ion based storage system. Finally, supercapacitors initially cost $2,400 to $6,000 per kWh of energy storage, while lithium ion batteries typically cost $500 to $1,000 per kWh, at least for electric car use.

So the advantage for supercapacitors for solar backup is primarily in the 200-400x longer charge/discharge life. The fast charge/discharge capability of the supercapacitors isn't that important for most renewable energy capture cases. So the question is: assuming you have the space to install a supercapacitor storage system that is 7 times larger than the typical Li-ion system, will the cost of replacing the Li-ion system X times over the life of your solar array (depending on the number of charge/discharge cycles), be less than the cost of the supercapacitor system?

If you have the room, sealed lead-acid batteries are even cheaper than Li-ion batteries for solar storage. Vented lead-acid batteries are cheaper yet, if you don't mind the issues of maintenance (liquid levels), and dangerous fumes when charging them. In any case both of these solutions have the shorter charge/discharge lifetime issue of all chemical-based batteries. So the main trade-off is a financial one: how many chemical battery system replacements would you have to make, before the longer life of the supercapacitors becomes economically feasible?

Skip

Skip Cave
Cave Consulting LLC


On Mon, Jun 28, 2021 at 3:24 PM Joachim Saupe via groups.io <jsaupe=yahoo.com@groups.io> wrote:
Hello John,
Super Capacitors can be charged and discharged quickly with a LOT of current.
Batteries have to be charged more slowly with lower current and batteries also should be limited in it's discharge otherwise the life of a battery is drastically reduced.

For Solar systems there is no sense at this point in time to use Super Capacitors because you don't have these high charge and discharge currents.
Now in automobiles you want a fast charge and you also want to be able  to use a LOT of current for short acceleration bursts. In that application Super Capacitors make sense.

Joachim

“The test of our progress is not whether we add more to the abundance of those who have much; it is whether we provide enough for those who have too little”
Franklin D. Roosevelt



On Monday, June 28, 2021, 11:58:58 AM CDT, JohnD. <john7damato@...> wrote:


1. Why would you use a super capacitor verses a battery bank? 

2. How do I detrrmine the size of the super caoacitor?

I am at the begining of the planning and trying to understand this concept. Do I use a super capacitor stand alone or with my batteries?

Thank you.

JD.


JohnD. <john7damato@...>
 

Thank you. I am beginning to understand it. 

Questions:

1. Are super capacitor solar systems dependent on high amperage to maintain the charge?

2. Or can they be charged at a slower rate and discharged at a slower rate? 

Comments welcome as always.

JD. .


Skip Cave
 

Questions:
1. Are super capacitor solar systems dependent on high amperage to maintain the charge?

2. Or can they be charged at a slower rate and discharged at a slower rate? 

Answer to both: 
No. You can charge a super capacitor as slow, or probably as fast as you have the available current.

The key issue here is that the output of a supercapacitor acts just like any capacitor (though it can be a very large one).

The energy charging circuitry for a supercapacitor can be a simple current source. Then, as the capacitor is discharged with a constant current, the output voltage of the super capacitor will decrease at a constant rate, ramping down to zero volts.  

This characteristic of supercaps requires that the energy extraction circuitry will need to deal with voltages from the max rating of the supercap down to near 0 volts, in order to fully extract all the energy from the supercapacitor cell. This is a unique requirement for extracting stored power from a supercap, and current solar battery storage systems don't typically have this capability. 

Traditional solar battery  charge/discharge control systems assume a battery voltage that stays within a narrow range as the battery discharges, so these systems won't work well with supercap energy systems. They typically won't be able to extract a  portion of the energy stored in the supercap, as it's output voltage drops closer to zero.

In order to take full advantage of a supercap storage system and it's extra-long-life capabilities, you would need a battery control system that was designed to handle the wide input/output voltage range of the supercap cell array.

Skip

Skip Cave
Cave Consulting LLC