High Current Low Voltage Power Source

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Discussion Overview

The discussion revolves around the need for a high current low voltage DC power supply, specifically targeting around 8 volts and 250 amps for an electrolysis experiment. Participants explore various methods to achieve this, including transformer use, diode bridges, and alternative power supply options.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests using a transformer to convert 110V AC to 8V DC, but questions how to achieve the DC conversion effectively.
  • Another participant mentions the need for high current diode bridges, noting that available options typically do not meet the required specifications.
  • Some participants propose using industrial power supplies, highlighting their efficiency and potential cost-effectiveness over time, while also noting their size and weight.
  • There is a discussion about the voltage requirements for electrolysis, with some suggesting that a maximum of 10 volts should be maintained to avoid unwanted chemical reactions.
  • One participant recalls a personal anecdote about using high voltage for electrolysis, reflecting on safety concerns.
  • Suggestions are made to consider alternative power sources, such as rewound microwave oven transformers or ATX power supplies, although concerns about current capacity are raised.
  • Participants discuss the voltage and current characteristics of electric welders, questioning their suitability as a power source for the intended application.

Areas of Agreement / Disagreement

Participants generally express a lack of consensus on the best approach to achieve the desired power supply, with multiple competing views on methods and safety considerations. There is also uncertainty regarding the specific voltage and current requirements for the electrolysis experiment.

Contextual Notes

Some participants note limitations in the availability of high current diode bridges and the challenges of achieving the necessary voltage and current levels safely. There are also unresolved questions about the efficiency and practicality of various proposed solutions.

Who May Find This Useful

This discussion may be of interest to individuals involved in electrolysis experiments, those seeking high current low voltage power supplies, and hobbyists exploring alternative power sources for experimental setups.

Clickster
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I am in need of a high current low voltage DC power supply, around 8 volts and around 250 Amps would be ideal.

A transformer could take a 110v 20a house line and using Pincoming = IPVP = Poutgoing = ISVS and
get (110vx20a)/8v= and get 275a which is good.

But how do I make that DC?

I know that diode bridges are the norm for converting AC current to DC current but I have done a fair amount of browsing and found none that have the requirements that I need. I think the most I have seen are like 35 amp continuous and 400 amp surge.

Anyone have any ideas?
 
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Clickster said:
I am in need of a high current low voltage DC power supply, around 8 volts and around 250 Amps would be ideal.

A transformer could take a 110v 20a house line and using Pincoming = IPVP = Poutgoing = ISVS and
get (110vx20a)/8v= and get 275a which is good.

But how do I make that DC?

I know that diode bridges are the norm for converting AC current to DC current but I have done a fair amount of browsing and found none that have the requirements that I need. I think the most I have seen are like 35 amp continuous and 400 amp surge.

Anyone have any ideas?

It would be helpful if you stated what you’re attempting to power, as well as the duration of time it must be continuously powered. Must you use 8 volts?
 
Its for an electrolysis experiment and duration of time depends on amperage. I think a max of 10 volts needs to be established, if it is over 10 volts, other materials with a higher reduction potential could come out.

http://www.cdupload.com/files/50887_syub2/curve.PNG

Anything under 50 amps will not be cost effective.
 
Last edited by a moderator:
At these low voltages and high currents the best way to go is a switcher. Don't even try to build your own. Go on Ebay and look. I have seen supplies like this at reasonable costs.
 
Do you have a price in mind? There's a lot of industrial power supplies out there that can do this no problem. However, they cost a small fortune and are very big and heavy.
 
Topher925 said:
Do you have a price in mind? There's a lot of industrial power supplies out there that can do this no problem. However, they cost a small fortune and are very big and heavy.

They also have efficiency levels high enough to pay for themselves after a long period of use in electroplating. The small ones (under 100A) aren't super expensive - roughly $3-$4/Amp, but are very efficient switching supplies with extremely stable output.
 
I found this on eBay, it looks to be what I need and not too expensive either. The only thing that it needs is 220v...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=400008509005
 
Last edited by a moderator:
Clickster said:
Its for an electrolysis experiment and duration of time depends on amperage. I think a max of 10 volts needs to be established, if it is over 10 volts, other materials with a higher reduction potential could come out.

http://www.cdupload.com/files/50887_syub2/curve.PNG

Anything under 50 amps will not be cost effective.

the voltage required for electrolysis is 1.24V only so wat i suggest u is that u connect 12V supply to 6 cells in series in this way u can avoid heat produced and generate more h2...the current drawn is dependent on the resistance of the cell u just need to take care of the voltage and heat generated...
 
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  • #10
That reminds me when I was 12 years old, with that cool new chemistry box, thinking "bah, who needs a battery, I'll get a faster electrolysis with a higher voltage!" and just dropping two wires into a cup of saline solution and then connecting them to a 110V power plug...

... ah, good times! :smile:
 
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  • #11
Use a 1200 Watt ATX power supply. You'll get 12 volts, not 8 but even the really good ones can be had for under $300. You may have to plug it into a dummy motherboard to make it turn on but that's easy too. Tap your power off the lines that would go to the graphics cards.

250 amps is asking too much. Even at 8 volts that's 2000 watts, too much for one standard US outlet to supply.
 
  • #12
Clickster said:
The only thing that it needs is 220v...

So what's wrong with 220 volts? If you are not comfortable and capable enough to be working with 220 volt mains electricity then I don't think you should be messing with this project.
 
  • #13
Averagesupernova said:
So what's wrong with 220 volts?
As the original poster has not logged in since he asked about a high current supply, and that was 3 years ago, he may no longer be closely following this thread.

Just wondering, what voltage are home electric welders?
 
  • #14
Oh jeez I hardly ever do that. I always look at the dates. Oh well...
 
  • #15
NascentOxygen said:
Just wondering, what voltage are home electric welders?

there are small ones that'll run from a 115volt 15 amp outlet and deliver sixty amps or so.

the old standby cathedral shaped Lincoln 225 amp needs 230 volts.
i run mine from a dryer oultlet.

new microwave ovens have inverters - I'm curious if one could rewind the output transformer with a few turns of large wire...
 
  • #16
jim hardy said:
there are small ones that'll run from a 115volt 15 amp outlet and deliver sixty amps or so.
But what is their open-circuit voltage? They are just a robust transformer, right? Or do electric welders include rectifiers?

I'm thinking a welder might furnish the avid experimenter with a robust source of low voltage AC?
 
  • #17
NascentOxygen said:
But what is their open-circuit voltage? They are just a robust transformer, right? Or do electric welders include rectifiers?

I'm thinking a welder might furnish the avid experimenter with a robust source of low voltage AC?

Welders make perhaps seventy volts to strike the arc.
Better ones have rectifiers and will say " DC "


Hobbyists are using microwave oven transformers (aka MOT) to make low AC high current for spot welders. They remove the high voltage winding and replace it with a few turns of BIG wire.

Four re-wound MOT's and something like these might make a versatile setup...
http://www.ebay.com/itm/Bridge-Rectifier-50-Amp-10-1000-volt-KBPC50A10-Aluminum-Casing-HEAVY-DUTY-/130592483935?pt=LH_DefaultDomain_0&hash=item1e67eb2a5f
and there's usually 150 amp ones on Ebay.

<<<WARNING>>> :: a microwave oven transformer with its high voltage winding still there is more dangerous than a handgun.
NEVER enegize one until the high voltage winding is physically removed. And i mean removed with a hacksaw.
 

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