Here’s a quick battery review for you. We got the Energizer XP20001PD Ultimate power delivery battery pack on sale at Fry’s Electronics last week. With the 20Ah power in a convenient form factor, it looked tempting.

The packaging is very enthusiastic, referring to the pack as ULTIMATE and calling it a “PD RocketHub.” As far as we can tell, there’s no USB hub functionality to be found. There are a pair of short charging cables included though: One USB-A to Micro-USB B and one USB-C to USB-C. There’s also a tiny instruction sheet.

Specifications:

The XP20001PD has a 74Wh/20000mAh battery with four USB-A ports (5V, max 4.2A over 4 ports) as well as a Micro USB input for charging (5V/2A). The distinction for this pack is a bi-directional USB-C port, supporting 5V/3A, 9V/3A, 12V/3A, 15V/2.4A both ways, as well as charging at 36W with 20V/1.8A and outputting 45W at a 20V/2.25A profile.

 

Testing:

We only tested USB-PD use cases, in and out, since there are many better options if you only need to charge USB-A type devices (like the RAVPower 22000mAh 5.8A three-port pack or the Anker Powercore 20100 4.8A two-port pack).

Our first test was to charge the pack up to full. We found charging of the pack was inconsistent, starting around 18W (19.4/1.72) dropping to .01 amps after a while. The first charge attempt had the pack getting pretty warm too, and it seemed like the battery may have swelled a bit (the pack wobbles when placed either side up on a flat surface). You’ll see from the photos above that this might just be poor construction quality, as other aspects of the design are somewhat ugly as well.

When the pack was connected to a USB Power Delivery device, the four LEDs for battery status switched to one red LED. This was concerning but consistent. Oddly, this happened even with the USB-C to Lightning cable connected, but with it not plugged into the iPad itself.

We tested with our two most common USB-C PD devices, an iPad Pro 12.9″ (1st Generation) with the USB-C to Lightning cable from Apple, and a Dell XPS 13 9370 laptop with a USB-C to USB-C cable from ZMI.

The pack did not rapid charge the iPad Pro as we would have expected. Normally the iPad Pro would start at about 5.1V/2.5A (~13W) and then reset to roughly 14.9V/1.9A (~28W) but we saw the charge start at 5.04V/0.08A  and jump to 15.0/0.06. That’s right, almost up to 1 watt of charging power on the meter. You may find it more productive to use the 12W output on a USB-A port with a standard Lightning charging cable.

The pack was quirky with regard to charging the XPS 13 9370, getting up to a 45W (19.7V/2.24A) profile but cutting in and out. The XPS is quirky itself, as we found with the ZMI battery, but this was excessive. We’d prefer a slow charge warning and 40W of input to a 4-5 second “Charging” / “On Battery” cycle any day.

Wrap it up:

In short, we were disappointed with the Energizer Ultimate “PD Rockethub” charging bank. Even at an out-the-door price of $45, we found the most important functionality (USB-C in and out) was lacking, at least for our devices. We’ll be returning it for a refund shortly.

If you can get it for under $50 and have a lower power laptop (i.e. a sub-30W Macbook) or a lower power mobile device (maybe a Pixel or other phone that charges at 18W), this might be the fit for you.

If you are looking for 28W iPad Pro or 45W laptop charging (especially the newer Dell gear), we’d suggest spending the extra $20 and going with the ZMI 20000mAh pack at $70. It consistently charges the Dell at 40W (albeit with a slow charger warning) and successfully does the 28W rapid charge for iPad Pro. And it also doubles as a USB-C to 2x USB-A hub on the go.

If you want higher powered charging for the Dell laptops, we recommend the PW7018LC Notebook Power Bank Plus from Dell, which provides 65W of USB-PD power and a USB-A port for charging or data connection to your laptop. (We own one of these, purchased at our own expense, and it works nicely.)

Further details:

Our basic USB-C charger testing gear is the Satechi USB-C Power Tester or the Plugable version of the tester. Plugable is rated for 200W (20V/10A); Satechi advertises 65W but told us via email 2 years ago that it would handle 299.7W (30V/9.99A). Both seem to handle 130W through the Dell TB16 Thunderbolt 3 Dock without issue.

GTrusted did a deeper analysis of this pack with much more interesting testing gear than we have. Check it out if you’re interested in the protocol details and deep test results.

Disclosure: As we wrote over on rsts11’s 2018 conference writeup, ZMI provided an unsolicited power pack and charger for us to try out, about two years ago. They did not ask for a blog post or coverage, and other than the free battery and charger, we received no compensation for the review or later mentions.

The Energizer pack in this review was purchased by us at a local retailer without any sponsorship or contact with the manufacturer. The discount we received was through the publicly available Fry’s promo code program.