Connecting two power supply units for maximum output

[pdust]

I have two power supply units that convert AC to DC, each providing a steady output of 12V and 30 amps. However, when connecting them in parallel, the total output remains 30 amps (each unit gives 15amps only). I suspect they are sensing the total current on the wires. My question: is there anything I can use to trick them into providing the full power of 50-60 amps? Thank you so much!

 

[Geoff1946]

What are you connecting to as a load, and how are you measuring the current ? Also, what sort of power supplies are they?

 

[pdust]

Measuring current using a Victron shunt. Two Victron BlueSmart IP chargers rated at 30 amps each. I believe they have some sort of measuring shunt inside, and they won't provide more than 30 amps when connected in parallel. Any thoughts?

 

[binky]

Measuring current using a Victron shunt. Two Victron BlueSmart IP chargers rated at 30 amps each. I believe they have some sort of measuring shunt inside, and they won't provide more than 30 amps when connected in parallel. Any thoughts?

probably worth a quick call to Victron technical helpline, it's not the sort of gear many will have encountered on here. Do let us know what they say.

 

[pdust]

probably worth a quick call to Victron technical helpline, it's not the sort of gear many will have encountered on here. Do let us know what they say.

Sad... That's what I thought when you started asking unrelated questions. Why? Because, according to electricity and current flow principles, any electrician can tell if there is any way to do it. As for Victron, they left my question unanswered. Why? Because they have a charger with a capacity of 60 amps available, and I guess another upselling technique they don't want to purchase two devices of 30 amps each, as it costs far less and provides better protection in case one breaks down. And guess what? The most of new Victrons are non-repairable as well : )

 

[binky]

Sad... That's what I thought when you started asking unrelated questions. Why? Because, according to electricity and current flow principles, any electrician can tell if there is any way to do it. As for Victron, they left my question unanswered. Why? Because they have a charger with a capacity of 60 amps available, and I guess another upselling technique they don't want to purchase two devices of 30 amps each, as it costs far less and provides better protection in case one breaks down. And guess what? The most of new Victrons are non-repairable as well : )

In that case I would go to one of the victron Facebook pages, where lots of expertise can be found. The nice thing about victron is that it has an extensive fan base who are very knowledgable

 

[Richard-the-Ninth]

Because, according to electricity and current flow principles, any electrician can tell if there is any way to do it

As electricians, we design a circuit according to requirements of the load, which in turn means cable size, cable length, earthing arrangements etc, there is also testing to ensure it is safe. (There is more.)

You are asking for specific advice for a piece of equipment that we hardly work on. That is why we can not help you, it is not because we do not want to help.

 

[pdust]

As electricians, we design a circuit according to requirements of the load, which in turn means cable size, cable length, earthing arrangements etc, there is also testing to ensure it is safe. (There is more.)

You are asking for specific advice for a piece of equipment that we hardly work on. That is why we can not help you, it is not because we do not want to help.

No, I am asking how to stop the device from sensing current on the wires, for example by using a diode, etc

 

[ProDave]

Basic ohms law. You have a power supply of a particular voltage and a load. the impedance of the load will determine how much current flows.

If you double the capacity of the power supply, it is still providing the same voltage, so the total current is still determined by the load. So you would not expect the current to increase.

The only time the current would be increased would be if the power supply was current limiting and then adding a second power supply in parallel would increase the available current.

 

[pdust]

Basic ohms law. You have a power supply of a particular voltage and a load. the impedance of the load will determine how much current flows.

If you double the capacity of the power supply, it is still providing the same voltage, so the total current is still determined by the load. So you would not expect the current to increase.

The only time the current would be increased would be if the power supply was current limiting and then adding a second power supply in parallel would increase the available current.

Thank you however When I tried to add a load, e.g. 45 amps, a negative charging figure of -15 amps appeared on the shunt monitor. There must be some sort of sensor that monitors the current flow and restricts the device(s) from providing more than 30 amps at any given time.

I wonder if putting in a 40A diode on each device would stop the feedback reading?

 

[poni]

would it be because they are smart chargers and when connected to battery it gets feedback from the battery (from increased back EMF as the battery reaches fully charged ) to say how much charge it needs, but when you connect two in parallel. they each think that the battery is near fully charged so they are now limiting the current getting ready to stopping the charge cycle

 

[poni]

I wonder if putting in a 40A diode on each device would stop the feedback reading

that may work , give it a go , don't forget your PPE, for when all the smoke gets out,

 

[pdust]

would it be because they are smart chargers and when connected to battery it gets feedback from the battery (from increased back EMF as the battery reaches fully charged ) to say how much charge it needs, but when you connect two in parallel. they each think that the battery is near fully charged so they are now limiting the current getting ready to stopping the charge cycle

That's true; however, they can also be switched to power supply only. If I disconnect the battery and set the load to 45 amps, it will stop working until I reconnect / disconnect. With the battery connected, the shunt would read -15 amps

 

[binky]

That's true; however, they can also be switched to power supply only. If I disconnect the battery and set the load to 45 amps, it will stop working until I reconnect / disconnect. With the battery connected, the shunt would read -15 amps

how much is a larger shunt v some large diodes? Looking at an installation video for the shunt, I can't see any obvious reason why your cunning plan wouldn't work

 

[poni]

there is an answer on their web page ,its to do with the length of the leads and how to connect them ,
what is your load of 0.54kW

If I disconnect the battery and set the load to 45 amps, it will stop working until I reconnect it or disconnect it again. With the battery connected, the shunt would read -15 amps

so you have a 0.54 kW load and battery's connected at the same time, will this not confuse the smart charger?

 

[Bruspark]

The answer is that two regulated power supplies will only share the load if their voltages are identical at every level of load. If you have one set to 12.1V and one set to 11.9 the 11.9 one will do nothing until the 12.1 ones current limit is exceeded. Then it will fold back and the 11.9V one will take the load

It s very bad idea in other ways if their power supplies can't deal with unlimited 12V on the output with nothing on the input. Often the output FET's fry

 

[pdust]

The answer is that two regulated power supplies will only share the load if their voltages are identical at every level of load. If you have one set to 12.1V and one set to 11.9 the 11.9 one will do nothing until the 12.1 ones current limit is exceeded. Then it will fold back and the 11.9V one will take the load

It s very bad idea in other ways if their power supplies can't deal with unlimited 12V on the output with nothing on the input. Often the output FET's fry

Both settings are absolutely identical; that's why they share 15 amps each, as I mentioned earlier.

 

[Geoff1946]

I did once have dealings with paralleling regulated supplies. We had three 50amp modules, supplied from three phase, to make a 150 DC output.
However, if I remember correctly, there were additional connections to be made between the regulators of the three. I think basically one module took control with the other two acted as slaves. Those units were specifically designed for that purpose though.

 

[pdust]

I did once have dealings with paralleling regulated supplies. We had three 50amp modules, supplied from three phase, to make a 150 DC output.
However, if I remember correctly, there were additional connections to be made between the regulators of the three. I think basically one module took control with the other two acted as slaves. Those units were specifically designed for that purpose though.

Thank you for the clue; it works now, providing a total of 50 amps "(Ve.smart network)"