Jump to content

Diodes for capacitor balancing?


Recommended Posts

Right... So I have a bank of supercapacitors with 50 ohm resistors on each cell to balance them.

It works great, but I'm not a fan of the leakage current.

So I got to thinking... Could I use something like a diode (zener?) to limit the maximum cell voltage but without excessive leakage below that threshold. I'm not too familiar with how zener diodes work. But if I get a 2.4v diode wouldn't that theoretically limit the maximum voltage of the cell to 2.4v?

Link to comment
Share on other sites

Could be a great alternative.

Zeners are commonly used as mini voltage regulators on circuit boards.

There's a few balancing circuits on eBay that are just arrays of diodes rather then resistors.

This post sent with 100% recycled electrons.
2004 BMW M3
Mechman 280A
2 - XS Power XP3000

1 - XS Power D375

500F of Maxwell SuperCaps (soon to be 1000F)
iPadMini2

Dash mounted O-scope
Audison bitOne (Remote DRC MP)
Highs Amp - PPI Art A404
Hertz HSK130 (HSK165 waiting...)
DC Audio DC9.0K
2- DC Audio XL12m2

LEGAL             - 147.3dB @ 41Hz
OUTLAW         - 150.2dB @ 45Hz

OUTLAW         - 145.7dB @ 30Hz
JUNE 2014 SOTM WINNER

2014 COLORADO PEOPLE'S CHOICE WINNER

SOTM BUILD:
http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026

sig-sized6_zps0265e669.png

Link to comment
Share on other sites

Interesting.

I was looking at diodes + a resistor to limit current going through the diode. That way if an individual cell gets too high it will be drained vs. how I'm set up right now where they are all drained, and the higher voltage cells are drained faster due to ohms law.

I guess this is more or less a public brainstorm since right now if my car is going to be sitting for more than about a week (for whatever reason) I need to unplug the capacitor bank. Kind of annoying

Link to comment
Share on other sites

In researching it a bit more, yeah when you reach the zener voltage, they'll start conducting which will be a problem.

Adding a current limiting resistor will drop your voltage to the cap-bank and throw off the voltage distribution to the diodes.

Hmmm, may have to think about this one...

This post sent with 100% recycled electrons.
2004 BMW M3
Mechman 280A
2 - XS Power XP3000

1 - XS Power D375

500F of Maxwell SuperCaps (soon to be 1000F)
iPadMini2

Dash mounted O-scope
Audison bitOne (Remote DRC MP)
Highs Amp - PPI Art A404
Hertz HSK130 (HSK165 waiting...)
DC Audio DC9.0K
2- DC Audio XL12m2

LEGAL             - 147.3dB @ 41Hz
OUTLAW         - 150.2dB @ 45Hz

OUTLAW         - 145.7dB @ 30Hz
JUNE 2014 SOTM WINNER

2014 COLORADO PEOPLE'S CHOICE WINNER

SOTM BUILD:
http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026

sig-sized6_zps0265e669.png

Link to comment
Share on other sites

Could you expand on that?

I'm envisioning in my head: Instead of a resistor wired to each capacitor, I'd have a resistor AND a diode. Cell voltage gets too high, diode conducts, resistor limits current to a safe level, once the cell voltage drops below the threshold, it will stop conducting and I'll have no more leakage

Link to comment
Share on other sites

get 5v if you get one 2.4v it;ll be like sticking a wire in it what a diode does it keep current from comming backwards it keeps it flowing one way.

02 dodge ram 1500 reg cab 3rd gen

2 sundown sd-2 d4

soundstream rub1.2500 amp

all sky high car audio-fuse,fuse holder,wire,ring lugs and rca

flex tech

box design by Joe X

supension-mcgaughys 2in drop spindal ,western chassis 6in flip kit,buddy custom c-notch

04 5.7l hemi motor swap and made it an slt eletric everthing

youtube channel-http://www.youtube.c...43?feature=mhee

http://www.stevemeadedesigns.com/board/topic/190882-02-dodge-ram-1500-3rd-gen/

Link to comment
Share on other sites

Any Diode will have a voltage drop across the diode, they will work for what you want, but will be limiting the cap bank potential. I say get rid of all that balancing circuit stuff it isn't necessary. Dozen's of USACI guys run caps, none of them run balancing circuits, and they run alot more caps then you have. :)

TEAM SOUNDQUBED -- TEAM SOUTH

TEAM S.O.B. - Founder & Captain

3x Streetbeat World Record Holder

2017 MWSPL 1st place Mayhem & 4th Xtreme 4 
2016 MWSPL 1st place Mayhem/2nd Adv 4/2nd Xtreme 4
2015 MWSPL 2nd place Mayhem & 4th Xtreme 4
2014 USACI 2nd place Streetbeat 5 - 162.6 db
2014 MWSPL 2nd place Xtreme 4 - 144.9 db
2013 USACI 1st place Streetbeat 4 - 161.9 db
2013 USACI 1st place Street Q+ - 162.8 db
2013 MWSPL 3rd Kaos2 & 4th Xtreme 4
2011 USACI 2nd place MOD 1001-2k - 160.0 db
2011 MWSPL 4th place: Adv3 - 157.8 db, Kaos2 - 150s db, Xtreme4 - 140s db
2010 ARSPL 1st place 501-750 - 160.3 db Arkansas loudest

Best score to date 164.4 db - Termlab Outlaw

Streetbeat 4 - 161.9 db

Streetbeat 5 - 162.6 db

MWSPL on Dash Legal door open (Music) - 162.5 db

Sealed on dash Legal (Music) - 161.1 db - Termlab

THE BLACK NASTY CURRENT BUILD & FAB

The Black Nasty (6) 15 Rebuild Log 2012

(4) 15 Walled Sierra Build Log

Evo X build log

Facebook page The Black Nasty

16163044_large.gif

Link to comment
Share on other sites

get 5v if you get one 2.4v it;ll be like sticking a wire in it what a diode does it keep current from comming backwards it keeps it flowing one way.

Why do you say 5v? My caps are rated at 2.7v and during usage don't see more than 2.36v ea

Any Diode will have a voltage drop across the diode, they will work for what you want, but will be limiting the cap bank potential. I say get rid of all that balancing circuit stuff it isn't necessary. Dozen's of USACI guys run caps, none of them run balancing circuits, and they run alot more caps then you have. :)

Ehh. I like to play things safe. It will cost me only a couple bucks to do it. I see it like a fuse: May not need it, but better safe than sorry. I don't see how they would limit the potential though? All I'd be doing is making sure all of the individual caps run around the same voltage vs. having some run at say 2.7v, others running at 2v, etc

Link to comment
Share on other sites

Explain to me how in a series bank you would have some running at 2 volts and some at 2.7, it is a cap not a battery.

TEAM SOUNDQUBED -- TEAM SOUTH

TEAM S.O.B. - Founder & Captain

3x Streetbeat World Record Holder

2017 MWSPL 1st place Mayhem & 4th Xtreme 4 
2016 MWSPL 1st place Mayhem/2nd Adv 4/2nd Xtreme 4
2015 MWSPL 2nd place Mayhem & 4th Xtreme 4
2014 USACI 2nd place Streetbeat 5 - 162.6 db
2014 MWSPL 2nd place Xtreme 4 - 144.9 db
2013 USACI 1st place Streetbeat 4 - 161.9 db
2013 USACI 1st place Street Q+ - 162.8 db
2013 MWSPL 3rd Kaos2 & 4th Xtreme 4
2011 USACI 2nd place MOD 1001-2k - 160.0 db
2011 MWSPL 4th place: Adv3 - 157.8 db, Kaos2 - 150s db, Xtreme4 - 140s db
2010 ARSPL 1st place 501-750 - 160.3 db Arkansas loudest

Best score to date 164.4 db - Termlab Outlaw

Streetbeat 4 - 161.9 db

Streetbeat 5 - 162.6 db

MWSPL on Dash Legal door open (Music) - 162.5 db

Sealed on dash Legal (Music) - 161.1 db - Termlab

THE BLACK NASTY CURRENT BUILD & FAB

The Black Nasty (6) 15 Rebuild Log 2012

(4) 15 Walled Sierra Build Log

Evo X build log

Facebook page The Black Nasty

16163044_large.gif

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Who's Online   0 Members, 0 Anonymous, 1164 Guests (See full list)

    • There are no registered users currently online
×
×
  • Create New...