Try a tiny bit of paper folded a few times and place between battery cover and battery. I've only used it a few times yet but it seems to have helped.
Placing a washer between the battery contacts seemed to make no real difference.
The real issue is between the three little pogo springs under the battery - there just is too much play and these can get lose in fast movement / slight hits such as tapping controllers together.
There's no denying that it's poor manufacturing / testing by Meta, which is a shame as everything else about it is great.
Try a tiny bit of paper folded a few times and place between battery cover and battery.
Ah, you've jogged my memory. Someone posted a few months ago about Meta rechargeable battery packs needing a bit of foam or paper taped to the inside of the battery cover to keep the batteries pushed into place. The washer or aluminium foil solution I suggested is for regular rechargeable batteries, not the Meta ones.
