Does this super capacitor balancing work?

[internetuser2k12]

Does this super capacitor balancing circuit works?????? The capacitors are rated 2.7 V 3000F The capacitors should not charge more than 2.7 volts.

 

[FvM]

The circuit allows for +/- 0.6 V variation of individual capcitor voltage. With low voltage margin, you should better refer to an OP based balancing circuit, as it has been discussed in previous edaboard threads. The current strength of a balancing circuit should be selected according to the charge current and expectable capacitor inbalance.

 

[internetuser2k12]

@FvM

Can you please provide the links for op amp based balancing circuits. I didn't find one.

I changed the circuit a little. Will this work?

 

[FvM]

Can you please provide the links for op amp based balancing circuits. I didn't find one.

Not a specific problem with your question, but I wonder why a large share of Edaboard posts is querying information, that can be found either by a board or google search? I need to operate the same search machines!

https://www.edaboard.com/threads/204875/

I changed the circuit a little. Will this work?

How should it? By the way, Edaboard users can expect a schematic readable by eye. Simulation circuits are optional and particularly interesting for problems that need further analysis.

 

[internetuser2k12]

@FvM

I checked the link. It was not helpful. Can you provide more links.

 

[FvM]

I checked the link. It was not helpful.

Why? I fear, the problem is either reading or understanding electronics.

 

[godfreyl]

I don't think the first circuit will work properly. There's nothing to balance the voltage between C2 and C3 or between C4 and C5.

I changed the circuit a little. Will this work?

Don't know, can't see it.

 

[FvM]

I don't think the first circuit will work properly. There's nothing to balance the voltage between C2 and C3 or between C4 and C5.

Yes, it should it be at least supplemented with a complementary driver for every tap. The other problem is the "loose" of +/- 0.6 V caused by transistor Vbe. So with 12 V input, the individual capacitor voltages can vary between 1.8 and 3.0 V. You could add a single bias diode for each transistor pair, reducing the loose to +/- 0.3 V.

Or use an OP based balancing circuit, as in the Epcos application note and other circuits discussed in the link.

 

[godfreyl]

The capacitors are rated 2.7 V 3000F

You might have to rethink the idea of using opamps for this. Even with a current of 1 amp, it would take nearly an hour to charge/discharge one capacitor by 1 volt.

Maybe power transistors/Darlingtons/MOSFETs controlled by opamps?

 

[internetuser2k12]

@ FvM

Can I use this circuit by extending the opamp stages to 6?

**broken link removed**

I will be using 12 V solar panel. The voltage will not exceed 14 V. I will replace the 310F supercapacitors in the circuit with 3000F SC.

 

[FvM]

Can I use this circuit by extending the opamp stages to 6?

Yes, it looks very similar to the active balancing concept suggested in the Epcos application note. It can be extended to any number of cells.

I must confess, that I didn't think about the restriction of simple OP circuit to a two-cell stack. Although it can be extended to multiple cells, it doesn't make much sense in this case.

 

[internetuser2k12]

@ FvM

I want to know can I use this circuit **broken link removed** by extending it to 6 supercapacitors. There will be 6 Op amp stages.

Can I use 2.& v Zener instead of LM 385??????

 

[FvM]

Yes, that's what I said.

 

[internetuser2k12]

Can I use 2.7 V zener instead of LM 385????

 

[FvM]

The reference voltage must be clearly below the circuit threshold. Accuracy with 2V4 Z-diode won't be very good, the voltage divider has to be recalculated of course.

 

[internetuser2k12]

How should be the connection of LM385? here http://www.discovercircuits.com/DJ-Circuits/SupercapVoltageLimiter1.pdf it doesn't show how to connect the third pin of LM385.

Should the FB pin of LM385 connected to anode of itself?????

http://www.ti.com/product/lm385-adj

http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS005250.PDF