Do transformers in chargers act as a load?

In summary, the conversation discusses the use of transformers in phone chargers and their behavior when no device is being charged. It is mentioned that even modern chargers, which use switching regulators, still have small current flowing through the transformers due to eddy currents and switching losses. The possibility of using a power meter to determine the load is also mentioned. The conversation also touches on the differences between linear and switched mode chargers and the potential risks of not using a transformer in a charger.
  • #1
themadquark
22
1
Due to the fact that I don't have any plans on damaging my chargers (something I am not planning to risk at the moment) I have not been able to confirm whether the transformers in chargers act as a load when nothing is charging. From what I have read, based on the design of many chargers, even when no phone/load is charging the resistance from the transformer in the charger causes it to act as a load and consume a few watts. I am asking for a confirmation of this possibly with a more in depth explanation for somebody who isn't what you would call an expert (me).
 
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  • #2
The transformer will still have small current flowing through them ... some of that is just pure leakage current.
Even just a plain transformer across the mains outlet, with no load on the secondary side, I suspect, will present a small load to the mains supply due to eddy current losses in the transformer core

Dave
 
  • #3
I think most chargers are switching regulator supplies that work over a wide range of input voltages (100V-240V, for example) They have switching losses even when no load is being drawn. Even a transformer and rectifier system will draw current with no load.

Can you explain more about why you care?

You can buy a power meter to determine the load. https://www.amazon.com/dp/B00009MDBU/?tag=pfamazon01-20 for example (there are a bunch, read the reviews)
 
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  • #4
meBigGuy said:
I think most chargers are switching regulator supplies that work over a wide range of input voltages (100V-240V, for example) They have switching losses even when no load is being drawn. Even a transformer and rectifier system will draw current with no load.

I was thinking of saying something to that effect. I don't think any phone chargers are using transformers anymore. (could be wrong)
 
  • #5
even if nothing is being charged, the transformer will still act as a load. it will burn a small amount of energy which is considered to be loss of the transformer.
 
  • #6
MrSparkle said:
I was thinking of saying something to that effect. I don't think any phone chargers are using transformers anymore. (could be wrong)

yes they still do. what changes is they are no longer linear. they use SMPS now a days just like a PC power supply but still transformer is being used.
 
  • #7
MrSparkle said:
I was thinking of saying something to that effect. I don't think any phone chargers are using transformers anymore. (could be wrong)

They better still be using transformers. I'm pretty sure I don't want 120 volts held against my face.

5 volts sounds much nicer.
 
  • #8
I guess my sloppy thinking got us here. All chargers have transformers. I was implying a linear AC transformer based system where there are some no-load losses due to the transformer, filter capacitors, etc. The switched mode systems have significant losses at no load due to the switching. Some switching circuits require small minimum loads to keep them in regulation.

For some reason I considered linear to be "transformer based" but in reality they are all transformer based.
 
  • #9
psparky said:
They better still be using transformers. I'm pretty sure I don't want 120 volts held against my face.

5 volts sounds much nicer.

you realize you can convert voltage without a transformer? Convert to DC, then pulse the DC current through an inductor. No transformer needed. And since the inductor would be smaller than an equivalent transformer, you save size and weight. I don't think I'd see a transformer if I opened up my phone charger.


meBigGuy said:
I guess my sloppy thinking got us here. All chargers have transformers. I was implying a linear AC transformer based system where there are some no-load losses due to the transformer, filter capacitors, etc. The switched mode systems have significant losses at no load due to the switching. Some switching circuits require small minimum loads to keep them in regulation.

For some reason I considered linear to be "transformer based" but in reality they are all transformer based.
why can't you just have a switch that cuts off the circuit when charger drops below a minimum current? or when the battery reaches a threshold voltage?
 
  • #10
MrSparkle said:
I don't think I'd see a transformer if I opened up my phone charger.

I think you would.

I would expect that all commercial regulatory approved wall wart style chargers are transformer based. But, I have not opened any to check. I expect many have a transformer the size of a dime.
 

1. Do transformers in chargers act as a load?

Yes, transformers in chargers do act as a load. A load is any device or component that consumes power from a power source, and the transformer in a charger is responsible for converting the high voltage from the power source to a lower voltage suitable for charging a device.

2. How do transformers in chargers act as a load?

Transformers in chargers act as a load by using the principle of electromagnetic induction to convert the high voltage from the power source to a lower voltage. This process creates a load on the power source, as it must supply the necessary energy to power the transformer and charge the device.

3. Can transformers in chargers cause a power overload?

Yes, transformers in chargers can cause a power overload if they are not designed properly. If the transformer is not able to handle the amount of power being supplied by the power source, it can cause the charger to fail or even potentially cause a fire.

4. How do I know if a transformer in a charger is functioning properly?

You can check if a transformer in a charger is functioning properly by using a voltmeter to measure the output voltage. The output voltage should match the voltage required for your device. If the output voltage is significantly higher or lower than the required voltage, it could indicate a malfunction in the transformer.

5. Are there any safety concerns with transformers in chargers?

Yes, there can be safety concerns with transformers in chargers if they are not designed or used properly. If the transformer is not properly insulated, it could lead to electric shocks. Additionally, if the transformer is not able to handle the power load, it could overheat and potentially cause a fire.

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