BATTERY PACK ZMI POWERPACK NO. 20: COMPACT EXTERNAL BATTERY CAN CHARGE A MACBOOK

The ZMI PowerPack No. 20 (Model QB826G) is the closest thing I've seen in many years to the kind of outboard laptop battery popular in the days when batteries burned through stored energy as quickly as sparklers. The PowerPack No. 20's prosaic name hides its massive output: up to 210 watts across three output ports simultaneously!

- GLENN FLEISHMAN

The name also undersells this sleek, surprisingly dense gray and black lithiumion power pack, which has ports just on one end to access the 90 watt-hour (Wh)/25,000 milliampere-hour (mAh) battery. That's about 50 percent more than an M1 MacBook Pro's battery. (ZMI lists 3.63 volts and 90Wh; the MacBook Pro has a spec of 58.2Wh, and we can back out from the battery's known mAh to get 11.3V as its discharge rate.)

You'll pay a price for it: $149, the current discounted price direct from ZMI, isn't spare change. But given the wallop the power pack packs, it's hard to complain the company charges too much.

The power pack has two USB-C ports and one Type-A port. Both USB-C ports double as inbound and outbound charging connections. The one at left when facing the ports—and labeled in incredibly tiny gray-on-black type as IN/OUT1-can charge at up to a blazingly fast 100W with a USB-C cable and adapter rated for that.

The second USB-C port (IN2/OUT3) maxes out at 45W.

The three ports have a similarly absurd amount of output power, and automatically adjust across a wide range of voltages based on the cable attached:

> USB-C (IN1/OUT1): From 5V to 20V, up to 100W maximum

> USB-C (IN2/OUT3): From 5V to 20V, up to 45W maximum