Test/Review of USB Load resistor 1A-2A (2xGreen resistor)

8 posts / 0 new
Last post
HKJ
HKJ's picture
Offline
Last seen: 4 days 8 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark
Test/Review of USB Load resistor 1A-2A (2xGreen resistor)

USB Load resistor 1A-2A
DSC_4394
Official specifications:


  • Color: Green.
  • Resistance: 1A, 2A
  • Size: approx. 80 *18*11mm
  • when the switch adjust to 1A, the green LED light (There is no green led or dual color led)
  • when the switch adjust to 2A, the red LED light

I bought from ebay dealer: finetech007
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.
DSC_4387
This type of load is very simple, two big power resistors, one permanently connected, the other controlled by the switch and a led to show if there is any power supplied to it.
DSC_4388
DSC_4389
DSC_4391
DSC_4398
DSC_4390 DSC_4392
Load testing


  • This type of load is only designed for 5V input.
  • Current change during 30 minutes with 1A load is 0.013A, i.e. 1.3%
  • Current change during 30 minutes with 2A load is 0.029A, i.e. 1.5%

USB%20Load%20resistor%201A-2A%20usb%20output%20voltage%20sweep
Being a resistor the current will depend on voltage.
USB%20load%20resistor%201A-2A
As expected the load current and power is stable with a resistor, except for a small drop due to temperature.
Temp3093
M1: 74,2°C, M2: 99,2°C, M3: 70,8°C, HS1: 213,5°C
One resistor gets fairly hot.
Temp3094
M1: 66,0°C, M2: 69,3°C, HS1: 112,4°C
The tinned area on the back will equalize the temperature, but do not really radiate any heat.
Temp3097
M1: 255,9°C, M2: 253,5°C, M3: 139,1°C, M4: 115,7°C, HS1: 275,6°C
Two power resistor this close will heat each other and gets very hot.
The correct way to mount power resistors is a bit above the board with some distance between. These resistors are only running at half their rated power, but they cannot get rid of the heat.
Temp3098
M1: 100,3°C, M2: 101,7°C, HS1: 160,1°C
Again the radiation from the backside is limited.
Conclusion
The load works as expected and is an easy way to test usb power banks (together with a usb meter), but this model really need an external fan to supply lots of cool air.
It is a very bad idea to touch it when it is working.
Notes
Expect very similar performance from all resistive loads with two round green 10W 5ohm resistors.

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

dchomak
Offline
Last seen: 3 years 2 months ago
Joined: 03/17/2012 - 20:10
Posts: 4122
Location: Connecticut

I have some of these! Very handy indeed.
It is surprising how many “2.1A” power banks can’t even push 2A into a simple resistive load

Your graphs are so straight! Wink

zelee
zelee's picture
Offline
Last seen: 2 weeks 1 day ago
Joined: 06/04/2013 - 06:53
Posts: 1966
Location: S.E.A

i got two of these to test load several power bank i have and it get hot real fast Innocent

dchomak
Offline
Last seen: 3 years 2 months ago
Joined: 03/17/2012 - 20:10
Posts: 4122
Location: Connecticut

Those kind of resistors are made to get very hot. What HKJ was pointing out was that for this application, the resistors being exposed like this, the user has to be careful not to get burnt.
As a coincidence yesterday I bought a second 3 Ohm power resistor to test Lithium drill packs. Here is a picture, it is huge and is rated at 175W. Probably NiChrome wire and it is wrapped around a ceramic cylinder. Same as a heating element. Even dissipating only 125W it gets hot enough to melt the insulation of ordinary house wire should it come in contact.



When I use it to load an 18V (21V fully charged) drill pack I lay it across 2 heat sinks just to keep it off the bench and help spread out the heat. The second resistor I bought is to be hooked up in series to test 40V packs.

Here are 2 – 2.2 ohm power resistors hooked in series. The combo is rated at 110W and got hot enough to melt the insulation of a lead in wire.

So getting back on topic, If you get one of these USB load resistors BE CAREFUL or you WILL get burnt.
Even though I knew, I got burnt. Not pleasant

zelee
zelee's picture
Offline
Last seen: 2 weeks 1 day ago
Joined: 06/04/2013 - 06:53
Posts: 1966
Location: S.E.A

i never use it for more than 20s, just need to know if my powerbank can handle 2A and as the result some of them successfully failure

HKJ
HKJ's picture
Offline
Last seen: 4 days 8 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark
dchomak wrote:
Your graphs are so straight! Wink

They are not that interesting, as I wrote above the interesting thing is how hot it gets.

dchomak wrote:
Those kind of resistors are made to get very hot. What HKJ was pointing out was that for this application, the resistors being exposed like this, the user has to be careful not to get burnt.

There is also a problem with the circuit board, it is best kept below 130C, to avoid long term effects.
That type of resistors are very robust, I have tried to overload some ceramic resistors significantly. Even when they start glowing red they will continue to work.

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

L4M4
L4M4's picture
Offline
Last seen: 9 hours 37 min ago
Joined: 12/08/2013 - 13:43
Posts: 1340
Location: Germany

I have one of the older types (smaller switch, Red/green 5mm duo-LED).
It draws 0.97 and 1.86 Volts (measured with the Xtar USB meter and a 10Ah Xiaomi PB).

I like this thing very much. Simple and effective way to check if a device can deliver a higher current.

will34
will34's picture
Offline
Last seen: 10 hours 7 min ago
Joined: 12/18/2012 - 00:12
Posts: 4074

I added 3 Al heatsinks to mine and secured with thermal epoxy:

With a USB fan for cooling, it can run for extended periods at 2A without getting too hot to touch. You can also run an USB extension cable and keep it inside the frigde. Leaving the powerbank and USB meter outside of course Smile