Review on Long-Lasting EBL 9V Lithium Rechargeable Batteries With USB 5400MWh Capacity (Pack Of 2) by Ryan Selpasoria

I bought this 4 pack of rechargeable 9V batteries because my electric and bass guitar have active pick-ups, and so have to be replaced every few weeks, or 2 months tops. They all charged okay, but I have no idea what the life on these are because all 4 had to be mashed into the battery bracket under tension. After turning on the amp, could hear the electric and bass guitars tone come through, but also a high pitched whining in the background whether notes were being played or not. Happened with all 4 batteries; switched back to old (non-rechargeable) battery and the whine went away. Oh well, back to spending $4-5 each battery (in 2022).