TheMrbunGee
Hazard to Others
Posts: 364
Registered: 13-7-2016
Location: EU
Member Is Offline
Mood: Phosphorising
|
|
Step down adjustable buck converter for electrolysis
Hey SM,
I am having some problems with power supply for electrolysis. I have nonadjustable 48V 30A DC power supply which I would like to use for electrolysis,
but I am running into some problems with adjusting the voltage.
Can't find any high power buck converters (there are 15 amp output ones, but no higher current).
I tried to get into building my own converter (I have some high power MOSFETs, diodes, capacitors and inductors laying around), but although my
profession is electric - I have some problems when it comes to electronics.
Maybe someone have any Ideas how could I get the voltage down to about 12V (better yet - adjust it) and still be able to push at least 40
Amps?
|
|
|
markx
National Hazard
Posts: 645
Registered: 7-8-2003
Location: Northern kingdom
Member Is Offline
Mood: Very Jolly
|
|
Quote: Originally posted by TheMrbunGee  | Hey SM,
Maybe someone have any Ideas how could I get the voltage down to about 12V (better yet - adjust it) and still be able to push at least 40
Amps? |
Well....there are such modules:
https://www.ebay.com/itm/800W-30A-DC-Buck-Converter-Step-dow...
Or you could buy a 5V 70A power supply and be done with it:
https://www.ebay.com/itm/Switch-Power-Supply-Driver-DC-5V-70...
Or you could pwm your existing power supply output with a mosfet based circuit and sink it into a nice big capacitor bank to smooth out the ripple and
get rid of voltage spikes.
For electrolysis you do not really need much over 5V (if you do not plan to run several cells in series off the same power supply). Except perhaps for
color anodizing Ti or some similar process.
Exact science is a figment of imagination.......
|
|
|
TheMrbunGee
Hazard to Others
Posts: 364
Registered: 13-7-2016
Location: EU
Member Is Offline
Mood: Phosphorising
|
|
| Quote: Originally posted by markx |
Well....there are such modules:
Or you could buy a 5V 70A power supply and be done with it:
Or you could pwm your existing power supply output with a mosfet based circuit and sink it into a nice big capacitor bank to smooth out the ripple and
get rid of voltage spikes.
For electrolysis you do not really need much over 5V (if you do not plan to run several cells in series off the same power supply). Except perhaps for
color anodizing Ti or some similar process.
|
Dude how did I not found that!?
And I did not even think of just buying a power supply, Thanks. I think I will stick with the 5V supply, maybe in the future try to make my own mosfet
converter.. 
Thanks a lot, feel a bit stupid, because I spent like 2 hours browsing ebay. 
|
|
|
markx
National Hazard
Posts: 645
Registered: 7-8-2003
Location: Northern kingdom
Member Is Offline
Mood: Very Jolly
|
|
You are most welcome !
Buying the power supply probably is the most efficient way to get ahead if your intention is conducting electrochemical experiments and not
concentrating on electronical topics.
Just do not buy the cheapest one available on ebay....they look the same, but are really crappy (no fuses, no grounding, noexistant assembly quality,
oh yeah and they like to burn like a merry hell)....
Exact science is a figment of imagination.......
|
|
|
RogueRose
International Hazard
Posts: 1585
Registered: 16-6-2014
Member Is Offline
|
|
There is always running cells in series, so if you wanted to run your 48v supply and run at 12v, you could run 4 cells in series. IDK your setup but
this type of thing works well for H2 & O2 generation by running alternating plates (isolated from each other) and you can also put a neutral plate
in between which seems to give higher outputs.
What are you trying to electrolisyse? If you are looking for 12v, there is always the car battery or SLA batteries from computer UPS backups. Are
you looking to run extended periods?
|
|
|
zed
International Hazard
Posts: 2277
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline
Mood: Semi-repentant Sith Lord
|
|
Um. Some chargers have a 30-50 Amp, "Jump" function. Might burn out if you tried to run continuously though.
As I recall, serious power supplies, cost serious money.
I however, do have 4 or 5, ordinary 10 Amp, 12 volt battery chargers.
Am I correct in supposing that I could hook them up in parallel to produce 12 volts at 40 Amps?
|
|
|
officescape
Unregistered
Posts: N/A
Registered: N/A
Member Is Offline
|
|
| Quote: Originally posted by RogueRose | There is always running cells in series, so if you wanted to run your 48v supply and run at 12v, you could run 4 cells in series. IDK your setup but
this type of thing works well for H2 & O2 generation by running alternating plates (isolated from each other) and you can also put a neutral plate
in between which seems to give higher outputs.
|
I second this method, with the caveat of hydrogen and oxygen generation as the author stated but thinking about it, it is probably an excellent way to
scale up electrochemistry, most of these designs have round cells in a round tube with the top of the round plate cut off on every cell so the gases
can combine and vent, as well as for loading and unloading.
George Wiseman has some really good designs out there and a lot of crazy ideas about the magical properties of electrolytic H2 gas.
|
|
|
yobbo II
National Hazard
Posts: 709
Registered: 28-3-2016
Member Is Offline
Mood: No Mood
|
|
Have a look at computer power supplies in parallel
It is possible to put two of theses supplies in parallel and isolate each supply from the rest by putting in a diodes into both leads from the
supply's. You may have to use identical units (which may be hard to come by) so that the current is shared equally between units. Do not run the
combined units at the max. new possible combined current as the supplies will probably not share the current equally among themselves.
Another alternative for using computer supplies in parallel is to connect all positives to the anode and connect each negative to a separate Cathode.
The Cathodes should be of equal size and spacing from the Anode and from each other. Diodes should also be placed in each supply to help isolate each
supply and stop current being driven into one supply from another.
According to pdfbq over on www.AmateurPyro.com computer power supplies can be connected in parallel without any diodes. Just simply connect the red wires (5V) together and
the black wires together. The problem that occurs is that it is impossible to turn on the power supplies at exactly the same time. As soon as the
first supply turns on it will be overloaded (by the low resistance load, a large cell in this case) and shut down. You must remove the Anode (or
Cathode or both) from the cell, turn on the paralleled supplies and then lower the electrodes slowly into the cell so that each supply can take up its
fair share of the load as the current builds up. You could also put a resistor in series with the cell that can be switched out of the circuit as soon
as you get all the power supplies switched on and running at the full current.
http://web2.murraystate.edu/andy.batts/ps/powersupply.htm
Have you looked into winding your own transformer using a microwave transformer (or other transformer core). Seriously cheap and serious current.
You can tap at the required voltage etc
Yob
|
|
|
Texium
|
Thread Moved
27-11-2023 at 12:15 |
yobbo II
National Hazard
Posts: 709
Registered: 28-3-2016
Member Is Offline
Mood: No Mood
|
|
Hello,
There are some rather LARGE smps at this link.
https://danyk.cz/index_en.html
As a side note:
I enjoyed the section on MOT sparks!
and the FAQ too.
|
|
|
Twospoons
International Hazard
Posts: 1282
Registered: 26-7-2004
Location: Middle Earth
Member Is Offline
Mood: A trace of hope...
|
|
For anyone wanting to 'roll-your-own' power supply, Texas Instruments have an online tool called Webench. This will take the input voltage and
output voltage and current you specify, search through TI's parts catalogue, and generate a bunch of designs that fit your specs, complete with a
parts list and simulation results. You can also choose to optimise for size, efficiency or cost.
https://webench.ti.com/power-designer/
Helicopter: "helico" -> spiral, "pter" -> with wings
|
|
|
Sulaiman
International Hazard
Posts: 3558
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
As you want 30A I'm assuming that this is for decomposing water to oxygen and hydrogen?
ie you want a high rate of decomposition.
If so then the 'best' approach would be many cells in series,
utilising both maximum available current and voltage from your power supply.
Current control:
There are so many options,
but I think that a good option would be to build more cells than you expect to need,
and adjust current by varying the number of cells in series.
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
yobbo II
National Hazard
Posts: 709
Registered: 28-3-2016
Member Is Offline
Mood: No Mood
|
|
Thanks TwoSpoons but
I put a design into the machine and it give me back a 'we cannnot do a design for your specs' (or somethign like that) + a pile of reasons why it
could not do it.
|
|
|
fx-991ex
Hazard to Self
Posts: 67
Registered: 20-5-2023
Member Is Offline
|
|
current too high.
|
|
|
Rainwater
National Hazard
Posts: 800
Registered: 22-12-2021
Member Is Online
Mood: indisposition to activity
|
|
$80
3.6kwatt 10-140v auto transformer branded as a welder
https://www.amazon.com/Pitbull-Ultra-Portable-100-Amp-Electr...
$50
4 100amp 1600v welding diodes
https://www.amazon.com/Fielect-Rectifier-Rectified-Repetitiv...
$12
5 200v 470uf caps total 2350uf of capacitors
https://www.amazon.com/Cermant-Capacitor-0-63x0-98in-Electro...
Should get you about a max of 30amps dc wired in full bridge configuration at 120v
Over 80amps at 60v
"You can't do that" - challenge accepted
|
|
|
Twospoons
International Hazard
Posts: 1282
Registered: 26-7-2004
Location: Middle Earth
Member Is Offline
Mood: A trace of hope...
|
|
| Quote: Originally posted by yobbo II |
Thanks TwoSpoons but
I put a design into the machine and it give me back a 'we cannnot do a design for your specs' (or somethign like that) + a pile of reasons why it
could not do it.
|
Well, building a 1.5kW offline isolated supply is not so simple. You likely need to start with a PFC, followed by a quasi-resonant full bridge
converter and finished off with synchronous rectification. Thats a fairly complex system, beyond what webench was intended for.
But if you already have a 48VDC server supply and you want to go down to a few volts at lots of current, then webench probably has an answer for you.
[Edited on 6-12-2023 by Twospoons]
Helicopter: "helico" -> spiral, "pter" -> with wings
|
|
|
yobbo II
National Hazard
Posts: 709
Registered: 28-3-2016
Member Is Offline
Mood: No Mood
|
|
The page allows up to 180Amps!
I don't know much about smps.
The links on the Chez. page
use MOT's to bring the voltage down to a lower level (from the mains).
Thanks,
Yob
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
