Cheap thrill here ($21.99). This little fellow can evaluate the performance and capacity of a USB power bank, and by extension an emergency radio that can charge a USB device. I have no confidence in product promises for battery bank capacity. I know that some of them, based on their weight alone, have impossible capacity specifications. One example had an advertised capacity MORE THAN THREE TIMES the theoretical maximum based on its weight.
When this arrives next week, I probably won’t publish an article on it, but I will be using it to test some of the power banks/emergency radios I have.
Update:
Well, that was fast. Careful reading of Amazon reviews and finally access to a product manual suggest that this model (the UT658DUAL) doesn’t supply a load. Some Amazon reviewers say it only provides a load for USB-A and not USB-C, but the manual says no load, period. So I ordered a load. Fortunately I caught it in time so they both ship together.
These only work for USB-A, but all of the things I have to test include USB-A outputs, so I should be good.
Not so Fast
Sigh. Those loads, pictured above have a small issue: they can’t handle the load. They have no cooling capability so they get hot and start smoking, at least that’s what the Amazon reviews say. I had to find something better.
This one has a fan and continuous rating of 15W. Two more days.
Update
The Leadigol tester arrived and it’s a rather neat package. I’ve hooked it up to my Bscame battery pack with an advertised 1000mAh capacity.
I have the load (lower right) sitting on a ceramic coaster, but at the 5W I’m drawing, it’s not getting much past warm.
The UT658DUAL displays capacity both in mAh and mWh, the second obtained by multiplying by Volts. The UT658DUAL assumes the voltage is what it sees, in this case 5.09V. Product listings typically assume that the voltage is 3.7 to match the value from a lithium ion battery. The only reliable capacity number is the mWh value.
The UT658DUAL has a significant problem in that when it finishes the test and the supply is exhausted, it loses power and the values calculated are lost. The best one can do is to press the save periodically and watch it like a hawk. (I wonder if I could power it from USB-C while it was testing USB-A.)
In this instance the last value I had was 31460 mWh, which divided by 3.7 yields 8502 mAh. Given that the charger is a year old and I didn’t have the exact last value before it shut down, I think that’s not bad for 10000 mAh power supply. It’s also never been deep cycled before.