The Fine PrintNothing here was tested in a lab. Every line below is a synthesis of what verified buyers report in their own reviews, including the complaints, which is the part most roundups leave out.
| Product | Capacity | Rating | The catch |
|---|---|---|---|
| Galaxy S26 Ultra Battery Case | 12,000 mAh | 4.4 (488) | Several reviewers say it barely delivers half a charge and the wireless connection can feel unstable. |
| Galaxy Ultra Battery Case | 12,000 mAh | 4.4 (389) | Several reviewers say the real capacity is closer to 4,000 or 5,000 milliamp hours than the advertised 12,000. |
| iPhone 17 Pro Max Battery Case | 12,000 mAh | 4.4 (42) | Several reviewers say the charging function stopped working entirely after a period of normal use. |
| Pixel Battery Case | 10,000 mAh | 3.5 (72) | Several reviewers say the real capacity falls well short of the advertised 10,000 milliamp hours, and charging is noticeably slow. |
| iPhone 15 Battery Case | 10,000 mAh | 3.2 (204) | Several reviewers say the charging port stopped working within a couple of months. |
All 5, in detail
Galaxy S26 Ultra Battery Case
Galaxy S26 Ultra battery case Reviewers say it's a straightforward upgrade over an older or worn out battery.
The catch. Several reviewers say it barely delivers half a charge and the wireless connection can feel unstable.
Galaxy Ultra Battery Case
Galaxy Ultra battery case Reviewers say it fits the S22 Ultra and S23 Ultra well and charges the phone quickly.
The catch. Several reviewers say the real capacity is closer to 4,000 or 5,000 milliamp hours than the advertised 12,000.
iPhone 17 Pro Max Battery Case
Reviewers say it comes in handy once the phone's own battery finally starts to fade during the day.
The catch. Several reviewers say the charging function stopped working entirely after a period of normal use.
Pixel Battery Case
Pixel battery case Reviewers say it helps get through a full day without needing a separate charger.
The catch. Several reviewers say the real capacity falls well short of the advertised 10,000 milliamp hours, and charging is noticeably slow.
iPhone 15 Battery Case
Reviewers say the case adds a solid extra charge with quick wireless pickup.
The catch. Several reviewers say the charging port stopped working within a couple of months.