[SOLVED] What parameters to tell if powerbank is good

[prometeusz]

I am repeatedly coming across unpredictable devices, probably because I want to pay 10 pounds rather than 2-3 times that amount, but here are the problems:

1. when connected to a small device such as headphones, stops charging after a few seconds. Changing cables usually makes not difference
2. very uneven results - phone sometimes charges instantaneously, and sometimes, it takes half an hour until the charge level picks up

What is the way to sort out these problems? I am hearing 1 is about 1A rather than stronger sources, whereas I am not sure about 2.

Thinking of buying some device to measure the Amperage, and Voltage and all that is useful to know but not more. There are devices for 12 pounds such as this one:

https://www.ebay.co.uk/itm/383943349520
and this
https://www.ebay.co.uk/itm/254939122492?var=554817997263

The former looks like a winner in terms of compatibility with a number of standards. Does it have all it gets? What is missing?

The latter appears to have more parameters being tested, but are all of them needed?

I am an absolute amateur - as you may have guessed - so anything beyond a simple testing of a charger, powerbank and maybe phone would be overkill.

Can you please advise?
Thanks

 

[lvt]

and this
https://www.ebay.co.uk/itm/254939122492?var=554817997263

I currently have this one, it does what it was designed for.

The other is more expensive but it might have more functions and USB-C port.

 

[lvt]

BTW I recommend the UM25C, a little more expensive but it has Bluetooth (see the data from your phone) and USB-C too.