Bought a used M2Z, inspected the batteries

[peterf]

And glad I did. The one on the right looks like somebody scraped off the gray sticker with a pocket knife. I assume this is supposed to be some kind of emergency valve. No idea what would compel someone to do this. I looked at the manual and the battery page shows the bare vent with no sticker, but I assume that's just a case of the 3D model they used for the illustration not having it. Every photo I see online has the sticker.

The labels on the two batteries have some slight differences in things like font and arrangement, I assume this can simply be down to the difference betwene production dates. However the label on the battery with the exposed vent also looks to be ever so subtly puffed, so I don't see myself attempting to fly with it.

I'm not necessarily asking for help, I'll cut my losses and replace this battery with a new one, just thought I'd share my findings. At least the other battery is much newer and seems to be completely unused with 0 charge cycles.

 

[dirkclod]

They might have scraped it off trying to get the swelling down.
No telling how it would look when it had been ran down and hot ?‍

 

[WobblingWillie]

And glad I did. The one on the right looks like somebody scraped off the gray sticker with a pocket knife. I assume this is supposed to be some kind of emergency valve. No idea what would compel someone to do this. I looked at the manual and the battery page shows the bare vent with no sticker, but I assume that's just a case of the 3D model they used for the illustration not having it. Every photo I see online has the sticker.

The labels on the two batteries have some slight differences in things like font and arrangement, I assume this can simply be down to the difference betwene production dates. However the label on the battery with the exposed vent also looks to be ever so subtly puffed, so I don't see myself attempting to fly with it.

I'm not necessarily asking for help, I'll cut my losses and replace this battery with a new one, just thought I'd share my findings. At least the other battery is much newer and seems to be completely unused with 0 charge cycles.

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You could use one of these to hold that battery in while flying low and close to you so you can get an idea of how much that battery is going to swell. I use one similar, that hangs my Rylo 360 beneath the drone and holds the one battery that I have that swells some, in place. Amazon.com: Ping.Feng for DJI Drone Connection Camera Adapter for DJI Mavic 2 Pro / 2 Zoom Connector Mount for OSMO Action for Insta360 ONE X Panorama Camera Camera Stand: Electronics

 

[StantonZ]

At this point, I would be more concerned with the SoC level these batteries were 'stored' at. They are definitely from different production batches (which may be a good thing), but you really won't know their health until you run a couple of cycles on them.