Test/review of USB Load resistor 2.2-4.7-10-20ohm with fan

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HKJ
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Test/review of USB Load resistor 2.2-4.7-10-20ohm with fan

USB Load resistor 2.2-4.7-10-20ohm with fan
DSC_9167
Official specifications:


  • 15 different load currents.
  • Resistors: 2.2ohm, 4.7ohm, 10ohm and 20ohm
  • Fan with two speeds

I got it from Banggood
The most interesting detail about this type of load is how hot they get, some power resistor has a working temperature between 200°C and 300°C when fully loaded. Due to the fan this will hopefully have more moderate temperatures, I have tested a version without fan before
DSC_9165
The load was in a plastic bag, no box or instruction sheet was included.
DSC_9172
All the leds works in parallel with a single resistor. The led at the usb connector is on when power is connected and uses about 0.7mA at 5V. The other leds will turn on when the switch for that resistor is turned on.
The fan is in parallel with the power input and there is a series resistor that can be switched in or out for low or high speed.
DSC_9168
DSC_9169 DSC_9171
DSC_9170
DSC_9174
The grid protecting the resistors is a good idea, even with the fan they can get hot.
DSC_9177
Load testing


  • The usb connector is NOT coded and Quick Charge or other signals must be generated with a trigger placed between this load and the tested power supply.
  • The higher value resistors in the load can be used with higher voltage if the fan is in “low” position.
  • With fan in “low” position the input voltage can be up to 14-15 volt.
  • The fan will probably blow if high speed position is used when input voltage is above 6 volt!
  • At low the fan stops at around 3V in the best cases, it is not reliable below 6V
  • At high the fan stops below 2V

USB%20Load%202.2-4.7-10-20ohm%20Voltage%20sweep%20low%20fan%20speed
Being a resistor the current will depend on voltage, but the fan add some extra current. This is most obvious at low current draw.
USB%20Load%202.2-4.7-10-20ohm%20Voltage%20sweep%20high%20fan%20speed
At high speed the fan will draw more current.
USB%20Load%202.2-4.7-10-20ohm%20Voltage%20sweep%20fan
Here is the fan current at low and high speed. The fan do not like above 6V, notice how the current draw increase dramatic in high at around 6V.
USB%20Load%202.2-4.7-10-20ohm%20Voltage%20sweep%2015V
The low fan speed is best used for higher voltage input, here I have tested 10 & 20ohm resistors with up to 15V input. I would not recommend using the two lower values with voltage above 5V. The ticks in the curves are from the fan, in it unstable below 6V when on low.
USB%20Load%202.2-4.7-10-20ohm%20load%20test%20high%20fan%20speed
Due to the fan there is a small variation in current, especially at the start where the fan needs more power to start.
20ohm resistor high fan speed
Temp5464
HS1: 35.7°C
Temp5465
M1: 31.6°C, HS1: 45.4°C
10ohm resistor high fan speed
Temp5466
HS1: 36.7°C
Temp5467
M1: 36.1°C, HS1: 73.8°C
4.7ohm resistor high fan speed
Temp5468
HS1: 45.4°C
Temp5469
M1: 42.5°C, HS1: 117.8°C
The temperature is perfectly fine for the resistor.
2.2ohm resistor high fan speed
Temp5470
M1: 35.5°C, HS1: 96.6°C
Temp5471
M1: 50.4°C, HS1: 179.4°C
Even this is fine for the resistor.
All resistors high fan speed
Temp5472
M1: 45.5°C, M2: 35.6°C, HS1: 111.6°C
The resistor get hots here, but not too hot for this type resistor and protective metal grid reduces the risk for nasty burns.
Temp5473
M1: 122.9°C, M2: 80.1°C, M3: 48.9°C, M4: 52.8°C, HS1: 165.3°C
20ohm resistor low fan speed at 12V
Setting the fan speed switch to high will probably destroy the fan!
Temp5476
HS1: 73.3°C
Temp5477
HS1: 129.2°C
The temperature on the resistor is acceptable.
10ohm resistor low fan speed at 12V
Setting the fan speed switch to high will probably destroy the fan!
Temp5478
M1: 38.6°C, HS1: 66.5°C
Temp5479
M1: 54.3°C, M2: 54.5°C, HS1: 273.9°C
Here the temperature is a bit too hot for the resistor.
Conclusion
With the added fan the load can handle much more power without getting too hot, some of the resistors can be used at higher voltage, but it is very important to switch the fan to low speed.
Due to the fan the current draw is not very precise, but as long as a usb meter is used to calculate mAh it is good enough.
This load is fine for testing mAh on power banks (with usb meter) or doing longer load test on usb chargers.
Notes
The device was supplied by Banggood.com for review.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

BlueSwordM
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That design is actually very smart.

Had they used a small aluminium finned sheet as a heatsink along with the fan, it would have been a great device.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

HKJ
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BlueSwordM wrote:
That design is actually very smart.

Had they used a small aluminium finned sheet as a heatsink along with the fan, it would have been a great device.

You do not need any aluminium near this type of resistor, airflow is the way to keep the temperature down.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

d_t_a
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I have the the USB load resistor without fan (similar to the model you reviewed before) – this USB load resistor (w/o fan) was bundled ‘free’ with the J7-4T USB meter I purchased last year from ETorch/HiDance (AliExpress).

I notice that the fan label in your picture reads “DC 5v 0.20A” , but you mention it can handle up to 14-15v when used in “low” fan speed.

On the older model, there are provisions to attached fan and fan selector, so I was thinking I could probably get a DC 5v 0.20A fan and a switch and likely convert it to something similar to the above. But was worrying will any DC 5v 0.20A fan work similarly or would it be better if the fan can be rated something else (eg. DC higher voltage, although this may mean the fan won’t start when voltage is at the normal USB 5v)?

Another concern, won’t the plastic of the fan melt up if it is positioned too close to those very hot resistors?

HKJ
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d_t_a wrote:
I notice that the fan label in your picture reads “DC 5v 0.20A” , but you mention it can handle up to 14-15v when used in “low” fan speed.

This is due to the series resistor, at 14-15V the actual fan voltage is 5V.

d_t_a wrote:
On the older model, there are provisions to attached fan and fan selector, so I was thinking I could probably get a DC 5v 0.20A fan and a switch and likely convert it to something similar to the above. But was worrying will any DC 5v 0.20A fan work similarly or would it be better if the fan can be rated something else (eg. DC higher voltage, although this may mean the fan won’t start when voltage is at the normal USB 5v)?

It is a question of balancing voltage and current consumption with the series resistor.

d_t_a wrote:
Another concern, won’t the plastic of the fan melt up if it is positioned too close to those very hot resistors?

It is a risk, but a high airflow reduces the risk. The fan on my test unit did not get any marks due to the hot resistors.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

A_M_K
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Another great review HKJ!

I have always wondered, if it makes any difference for a powerbank, wall charger or any similar type of electronic power source, if you test them with load resistor or a load transistor ??

HKJ
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A_M_K wrote:
I have always wondered, if it makes any difference for a powerbank, wall charger or any similar type of electronic power source, if you test them with load resistor or a load transistor ??

Yes and no.
An electronic load will usual draw a constant current, this means that the current will stay the same if the output voltage drops. In a resistor the current is voltage depend, this means the current will go down when the voltage drops. Due to this difference the behavior when at maximum load may vary between the two.

An electronic load may also produce some noise, this can affect noise measurements.

In my test you can always see when I am using an electronic load or a resistor. With the electronic load I specify the load in amps, with the resistor I specify the load in ohms with a conversion to amps (5ohm -> 1A).

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/