Maxwell Supercapacitors instead of 5V linear power supply

[sckramer]

Hello,

I'd like to experiment with a pair of 2.7V (5.4V) Maxwell supercapacitors to replace expensive audio linear power supplies, like the CiAudio 5V for the squeezebox, or powering a Hifiberry Dac+ Pro. (a linear power supply really improves the sound of this)

Here are the caps:

Maxwell 310 Farad 2 7V Ultracapacitor Supercapacitor D Cell Boostcap x 2 Pieces | eBay

1. To start I'd like to be able to charge it from standard 5V usb switching power supplies, is there a simple module to use or some regulator part?

2. Output very clean 5V DC, is there a module or regulator part for that?

Just trying to avoid reinventing the wheel, maybe someone has done this already?

Once up and running, I plan on expanding on the idea, auto-charging when it starts to get low, using a relay to disconnect the charge, etc.

Thanks!


Moving this to power supplies --

 

[Chris Daly]

Hello,

I'd like to experiment with a pair of 2.7V (5.4V) Maxwell supercapacitors to replace expensive audio linear power supplies, like the CiAudio 5V for the squeezebox, or powering a Hifiberry Dac+ Pro. (a linear power supply really improves the sound of this)

Here are the caps:

Maxwell 310 Farad 2 7V Ultracapacitor Supercapacitor D Cell Boostcap x 2 Pieces | eBay

1. To start I'd like to be able to charge it from standard 5V usb switching power supplies, is there a simple module to use or some regulator part?

2. Output very clean 5V DC, is there a module or regulator part for that?

Just trying to avoid reinventing the wheel, maybe someone has done this already?

Once up and running, I plan on expanding on the idea, auto-charging when it starts to get low, using a relay to disconnect the charge, etc.

Thanks!


Moving this to power supplies --

Hi
I would be asking the seller if these are a self contained voltage source
ie a battery, or if they are a capacitor with the stated capacitance and
voltage ratings but borrowing the word D cell along the way.

If you are buying a capacitor then series connection is
viable at the voltage you need . Voltage then is C1+C2 and capacitance
C1xC2 / C1+C2 ie half the capacitance.

If they are just a capacitor - you will still need a voltage source.

Cheers / Chris

 

[sckramer]

Here they are:

Maxwell Technologies D Cell Series Ultracapacitors Board Mounted Cells

2 in series should be 5.4V

I'd like to make the simplest circuit possible to charge these, and an output regulator/circuit to supply quiet, pure 5V DC -- to power audio circuits.

 

[Chris Daly]

The manufacturer states:
The cells work in tandem with batteries for applications that require both a constant low power discharge and a pulse power for peak loads. In these applications, the ultracapacitor relieves batteries of peak power functions resulting in an extension of battery life and can allow a reduction of overall battery size and cost.

So the information is clear to me they are a capacitor, not a self contained voltage source.
You need to decide to use batteries - 4x 1.2v is close at 4.8v, most circuitry would not be too fussy
with small voltage drop. the difficulty with batteries though is when charged voltage can be
slightly higher, and when discharged lower, and time needed to charge.

A simple circuit being 5x 1.2v in tandem with 3x series ultracapacitor , then using a LM317
or LM338 as a current regulator set to be capable of the current your DAC draws
will drop 1.2v - and be quite close for the majority of the time at 5v. many other variations
are possible.

For charging you would arrange ultracapacitors to be switched out of circuit, as voltage
during charging is always higher.

 

[sckramer]

Ok, looks like D-Cell refers to the physical size only.

So do you think I can build a circuit to imitate a battery, or really 5V DC, ~0.5/1Amp max output (but low noise like a battery), that's my plan-- maybe there is a prebuilt module, or something like a linear regulator part I can check out and research?

 

[Chris Daly]

Ok, looks like D-Cell refers to the physical size only.

So do you think I can build a circuit to imitate a battery, or really 5V DC, ~0.5/1Amp max output (but low noise like a battery), that's my plan-- maybe there is a prebuilt module, or something like a linear regulator part I can check out and research?

Yes you can get exceptional low noise capability with supplies that are not batteries
Walt has given in this article instructions for the supply, instead being 5v Walt's Blog 2014 | Walt Jung's 2014 Blog and Info Archive

 

[AndrewT]

Use a CCS to limit the charging current to whatever value you think is appropriate.
Use a series regulator after the CCS to limit the charging voltage to what ever you think is appropriate.
The CCS could be a 3pin lm317 regulator if your maximum charging current is <1.5A

 

[DF96]

I am not certain how you will charge a capacitor to 5.4V from a 5V supply, and then regulating down to 5V from 5.4V will need a very low drop regulator - which may have inferior performance to one which has more room to operate in.

How low can you discharge it before you will need to recharge it again? Let's assume you can discharge by 0.1V before the regulator loses control. Let's assume that you will draw 100mA from it. You have 155F, so 0.1V means 15.5C. At 100mA that is 155s - about 2.5 minutes. About long enough for a 1960's pop song.

 

[cbdb]

Using them in a C L C filter between supply and circuit might be your best bet.

 

[cbdb]

You might want to check there output impedance, I seem to remember these are chemical caps not the usual 2 plate caps. They might be slower than regular caps.