+ Post New Thread

Results 1 to 5 of 5

- 12th July 2012, 15:41 #1

- Join Date
- Apr 2010
- Location
- chania greece
- Posts
- 88
- Helped
- 3 / 3
- Points
- 1,294
- Level
- 8

## Charging/Discharging a supercapacitor.

Let's say I feed a series of supercapacitors from a PV panel with a 5V and 5mA average.

With the use of a boost regulator after the supercapacitors I want to to have an output

of 5V and 500mA.

How can I find how much will the discharging time of the supercapacitors will be

when I want them to produce 5V along with 500mA output?

Please ignore the balancing circuit for the supercapacitors or the input regulator after the

the PV panel.

Thank you in advance.

- 12th July 2012, 15:41

- 12th July 2012, 18:51 #2

- Join Date
- Dec 2010
- Location
- Southampton and holiday cottage in Wensleydale (UK)
- Posts
- 4,796
- Helped
- 1291 / 1291
- Points
- 24,825
- Level
- 38

## Re: Charging/Discharging a supercapacitor.

A 1 farad capacitor will loose 1V if the current drain is 1 A/Second, so your one will loose .5V /second. But the current will change as the voltage on the cap decays so as your load is 5/.5 = 10 ohms, once you have decided on the capacitor value, you can work out the time constant and apply the equation.

Frank

1 members found this post helpful.

- 12th July 2012, 18:51

- 13th July 2012, 10:17 #3

- Join Date
- May 2011
- Posts
- 192
- Helped
- 61 / 61
- Points
- 1,827
- Level
- 9

## Re: Charging/Discharging a supercapacitor.

According to your explanation, you will be taking a

**constant power**from the supercapacitors (considering an ideal boost). The calculation can be easy:

Energy available in the capacitors = 1/2 * C * ( (5 V)^2 - (Boost_Min_Input_Voltage)^2).

Time = Available Energy / (Power/boost_efficiency)

(you will be draining 2.5W/boost efficiency power from the supercapacitor)

1 members found this post helpful.

- 13th July 2012, 10:17

- 13th July 2012, 14:55 #4

- Join Date
- Apr 2010
- Location
- chania greece
- Posts
- 88
- Helped
- 3 / 3
- Points
- 1,294
- Level
- 8

- 16th July 2012, 07:12 #5

- Join Date
- May 2011
- Posts
- 192
- Helped
- 61 / 61
- Points
- 1,827
- Level
- 9

## Re: Charging/Discharging a supercapacitor.

Exactly. Therefore, if you improve boost efficiency you will increase the available time.

1 members found this post helpful.

+ Post New Thread

Please login