I’m just trying to find a cheap way to build a power supply capable to delivering 12V at 10A with some adjustments of I and V to maintain them.

Suggestion: Buy a 12 volt 10 amp switching power supply such as the Mean Well LRS-150-12 and add an adjustable current limit circuit to the output.
Steve G

 

Suggestion: Buy a 12 volt 10 amp switching power supply such as the Mean Well LRS-150-12 and add an adjustable current limit circuit to the output.
Steve G

Thanks. I’ve found a guide to building an AXT based one with the current limiting control. That should do fine.

 

The PSU you have shown is good for 10A @ 30V. I have some of those. What is wrong with that one?

 

The PSU you have shown is good for 10A @ 30V. I have some of those. What is wrong with that one?

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As I say in the post I made in the Power section, the max voltage I can get out of it when connected to the cell is 4V at 9 A. I need about 9 @ 12V so I guess it’s rating is much better than it can deliver. It’s managing less than 40W when I need about 130W.

Reviews of that PSU are not that good but it does for low power requirements. Hence I need to build a beefier one.

 

You are not paying attention.
Do you know how a constant current power supply works?
As I have stated in numerous posts in your other thread, current and voltage settings are maximum limits, not operating values.

If you set the current limit to 5A and the voltage limit to 12V, one of the limits will always kick in, whichever comes first.

If you are drawing 4A, the PSU will limit to 12V, because that is the setting you had set on the voltage limit.

If you hit the 5A limit first, the PSU will be at some voltage lower than 12V, because the current limit has been reached.
You do not get 5A @ 12V output unless the load happens to be exactly 12V / 5A = 2.4Ω. That is not what your load is. Your load is not constant so one of the two limits will kick in, whichever is reached first, current or voltage, not both.

Your PSU is indicating 3A @ 5V. This suggests a load of 1.7Ω. Assuming that the load remains constant, the most you can get at 12V is about 7A, or 84W.

If you want to operate at 12V then set the voltage limit to 12V and turn the current setting fully clockwise to max.
If you want to operate at 9A, then put a temporary short across the PSU output terminals and set the current limit to 9A.
The maximum power you can ever get with this setting is 9A x 12V = 108W.

If your PSU cannot supply 300W when adjusted correctly then it is not working properly.

 

JulesP,
This is what happens when you post on two forums on essentially the same problem.

 

You are not paying attention.
Do you know how a constant current power supply works?
As I have stated in numerous posts in your other thread, current and voltage settings are maximum limits, not operating values.

If you set the current limit to 5A and the voltage limit to 12V, one of the limits will always kick in, whichever comes first.

If you are drawing 4A, the PSU will limit to 12V, because that is the setting you had set on the voltage limit.

If you hit the 5A limit first, the PSU will be at some voltage lower than 12V, because the current limit has been reached.
You do not get 5A @ 12V output unless the load happens to be exactly 12V / 5A = 2.4Ω. That is not what your load is. Your load is not constant so one of the two limits will kick in, whichever is reached first, current or voltage, not both.

Your PSU is indicating 3A @ 5V. This suggests a load of 1.7Ω. Assuming that the load remains constant, the most you can get at 12V is about 7A, or 84W.

If you want to operate at 12V then set the voltage limit to 12V and turn the current setting fully clockwise to max.
If you want to operate at 9A, then put a temporary short across the PSU output terminals and set the current limit to 9A.
The maximum power you can ever get with this setting is 9A x 12V = 108W.

If your PSU cannot supply 300W when adjusted correctly then it is not working properly.

As I have said several times it is not working properly. I did not set any such limits and 9A @ 4V was with all controls set to maximum.

 

JulesP,
This is what happens when you post on two forums on essentially the same problem.

So I see. I considered it a different problem from the water level one and so posted it accordingly. Then you advised me to keep the different problem with the earlier one. So I did.

Anyway the path is clear now. Thanks for all contributions.

 

As I have said several times it is not working properly. I did not set any such limits and 9A @ 4V was with all controls set to maximum.

With both controls set to maximum, your PSU is working. It hits a max current of 9A first @ 4V, i.e. it goes into current limit mode.
What you need is a PSU that can supply at least 30A @ 12V = 360W.
Higher current output, e.g. 50A @ 12V = 600W will give you more headroom.

 

With both controls set to maximum, your PSU is working. It hits a max current of 9A first @ 4V, i.e. it goes into current limit mode.
What you need is a PSU that can supply at least 30A @ 12V = 360W.
Higher current output, e.g. 50A @ 12V = 600W will give you more headroom.

That’s right so now you have reached the start of my thread which is about how to build a ‘beefier’ PSU as cheap as chips. I’m opting for the ATX option which can be formatted with various options like with a current limiter. Shouldn’t cost me more than £35 all in.

 

But do you understand that you cannot control both current and voltage at the same time?
If you limit the current the voltage must fall below your voltage setting.

 

But do you understand that you cannot control both current and voltage at the same time?
If you limit the current the voltage must fall below your voltage setting.

I have always done so. My cheap PSU has a rather overrated power output