Sorry for the late. On the 5v systems I installed a filler to help reduce pwm noise caused by most battery chargers and cooling fans that may be added to the same power bank.. The filter reduced or eliminated the noise depending on the battery manufacturer.
There were a couple battery manufacturers I could sell or recommend to customers that would eliminate the noiseeven further however, with manufacturers constantly changing their designs or quit making batteries all together I grew tired of chasing the rabbit, so I stopped offering the 5v version. A hard decision though necessary.
That said, though the filter helps to reduce the noise you need a specific battery to eliminate it completely. These batteries have a feature and are designed to be powered on and remain on regardless there's a device plugged into it or not. Most batteries are not like this, most shut off after 30-60 seconds of not charging or if the device being powered falls under a 30mAh draw. The SHA draws 15mAh.
If you have further questions please let me know.