# Where could I find a high-amp constant current power supply?

1. Feb 18, 2014

### Xtensity

All of the ones I've seen online can only do about 30 amps tops... then there are welding machines, which I am not sure if those can used for non-welding applications without modification of the machine. I am not looking for something that is variable, just something that can output a high current(30-1000) while adjusting the voltage accordingly. I found some supplied by various companies but they do not have prices listed and are likely very expensive - such ones the voltage and current can be adjusted, which I do not have a particular need for that feature.

2. Feb 19, 2014

### meBigGuy

What voltage range? I understand you want a current source, but what is the highest voltage it will need to be able to produce, and at what current.

Or, asked another way, at 1000 AMPs, what do you expect the output voltage to be? There is a big difference between 0.1V and 24V (100 watts vs 24KW)

3. Feb 19, 2014

### Xtensity

The max voltage I would need would be 2, maybe 2.5 volts tops.

4. Feb 19, 2014

### meBigGuy

Last edited: Feb 19, 2014
5. Feb 19, 2014

I've seen many of these.... trying to stay under $1,000. I do not need the system to be variable, which I think is what really hikes the price up, but rather I need a constant and steady high current output. For instance 200 amp welding power supplies are a few hundred bucks... but a 200 amp variable switching power supply might be a thousand or so. The former option is clearly available in the form of a welding power supply, but my question is are there other forms of CC power supplies with higher current outputs? 6. Feb 19, 2014 ### Baluncore Firstly, what is your application? Do you only need to limit the peak current? How constant must the current be? Bandwidth, how quickly must the regulator respond? Gradient field amplifiers used in MRI would be ideal. There are several lower cost solutions. For a low voltage output it is most efficient to use a rotary converter such as a DC generator driven by an AC motor. Current regulation can be achieved through feedback to the field. The next most efficient solution would be a switching converter using synchronous MOSFETs instead of output diodes. A welder is designed to produce between 20 and 40 volts when operating. You could reduce the number of turns on the secondary of the welding transformer to say three turns of copper strap. That would reduce the supply current needed while increasing available current and efficiency. Some older welders have a movable magnetic shunt that is used to regulate current. That might be used to limit the current. I use such a system to fast charge truck batteries through a 500 amp bridge rectifier. 7. Feb 19, 2014 ### Xtensity I intend to electroplate very large items as well as other related applications. I just need the current to be a high number, in the range of 600-1000, steady. CC - Constant current. How Constant? I was under the impression most CC power supplies can keep the current decently constant by adjusting the voltage to compensate for resistance changes. Bandwidth... for my applications this probably isn't too important. If the answer "not slow" tells you anything. I am not a power supply expert - just for the record.. so I do not know much about this. I am not looking to modify any existing power supplies to a great extent. This isn't really my field of expertise. Is there no such thing as a CC(constant current) high amperage power supply, say maybe around 2kW, with amperage 600+? 8. Feb 19, 2014 ### Baluncore I would suggest you experiment with a low cost caddy welder. It will cost about US$350.
If it does not work then you can return it under warranty, or sell it on the second hand market.

Select based on the current available at continuous operation = 100% duty cycle.
Set to DC. Turn off any pulse mode. Wind the voltage right down. Wind the current up.

9. Feb 20, 2014

### Xtensity

I will look into it. On such a device, with constant current mode, the voltage auto adjusts, correct? I was somewhat thrown off by when you said to set both the voltage and the current.

10. Feb 20, 2014

### jim hardy

11. Feb 20, 2014

### Baluncore

With a caddy welder, current is limited but so is the droop voltage to maintain the arc. They are designed to primarily regulate current. It is able to produce more voltage than you need. It is just a constant current supply with a voltage limiter.

I would use a second hand choke welder, heavy but cheap, with some secondary winding turns removed, half the windings, twice the current. The industrial bridge rectifier could be from a DC adapter, (ex MIG or TIG).

12. Feb 20, 2014