If you’ve bought a Google Pixel 10 series phone, odds are you’ve been looking at compatible Qi2 and Qi2 25W accessories and wondering what to pick up. A desk charger like the Pixelsnap Charger with Stand, a magnetic wallet, a MagSafe-compatible tripod — all of these are good ideas. But the one accessory I was personally looking forward to the most is a Qi2 power bank. Just snap it on the back of my phone and get a relatively fast charge without any wires or tangles.

I ended up with several of these portable batteries to test out, and while I do appreciate their convenience, one thing stood out in all of my tests: You should really be wary of the battery’s capacity. 10,000mAh won’t be enough to charge your ~5,000mAh Pixel 10, 10 Pro, or 10 Pro XL more than once.