Anker Prime 20,000mAh (250W) — measured review
The Anker Prime 20K is the power bank to buy if you charge a laptop and phone together, delivering a measured 62.1 Wh of usable energy (86% of its rated 72 Wh) and a true 100W on its top USB-C port. It is heavier than travel-first packs, so pick it for a work bag, not a jacket pocket.
Tested · sample bought · rating 4.5/5 · how we test
| Rated energy | 72 Wh |
|---|---|
| Measured usable energy | 62.1 Wh |
| Measured efficiency | 86.3% |
| Max output | 100 W |
| Measured weight | 428 g |
| Passthrough | Yes |
Who it’s for
Buy the Anker Prime 20K if you regularly top up a USB-C laptop and a phone away from an outlet and can absorb the weight. If you want something for a jacket pocket, it is the wrong pick — see the lighter options in our best travel power banks roundup.
What we measured
We discharged the pack at a constant 15W into a Power-Z KM003C and logged total delivered energy across three runs. It returned a mean of 62.1 Wh, or 86.3% of the 72 Wh rated figure — the highest efficiency in the six 20,000mAh packs we have tested. Both USB-C ports held a full 100W individually; run together they split to a measured 140W total before the pack throttled.
How it compares
Against the UGreen 145W 20K, the Anker delivers 4.2 Wh more usable energy but weighs 41 g more. If total delivered energy per gram is what matters to you, the UGreen edges it; if you need dual 100W outputs, only the Anker sustains them.
Test conditions
24C ambient, 3 discharge runs at 15W constant, sample purchased at retail (not a PR unit). Full rig and repeatability notes: power bank methodology.
Where to buy: Amazon