XTAR PB2S

The Product

XTAR has a new portable charger/powerbank on the market. This one is available in a few colors, powered by two 18650 or 21700 cells, can output from two ports, and is charged with a USB-C cable.

Spoiler

I liked the original PB2 a lot. As far as I can tell, XTAR took every single issue people had with the PB2 and fixed or improved it for this version:

  • More descriptive display
  • Support for protected and larger cells
  • Added a USB-C port for input and output
  • Can charge two devices at once
  • Added an easier way to remove cells
All that to say I'm impressed. In my testing I kept looking for something to dislike about this device, and there really isn't anything notable. I always like carrying power banks like this one on trips, where I can swap out the cells in my light with the ones in the charger, and this is the new best-in-show device to beat.

Physical Dimensions

The PB2S measures 125 mm tall by 58 mm wide and 28 mm thick.
For comparison, here's the PB2S lined up with a few other power banks and combo power banks of mine - the Armytek Handy C1 Pro (single bay with NiMH support), Rofis MR30 (21700 flashilght combo), XTAR PB2 (2x18650), and Nitecore F4 (4x18650).

Build

The entire charger is made from a polycarbonate with a soft-touch finish, much like the original PB2. It attracts some finger prints, but seems to stand up well to daily wear.
The front of the charger has a translucent black panel at the top hiding the display, and the company logo silk screened on to the lid.
When in use, the screen shines clearly through the plastic.
The lid is connected at each side with a strong magnet, and pops open to reveal the two bays. They're shown here with long protected 18650 cells, but will also accommodate wider 21700 cells. The small ribbon gives an easy way to remove the cells from the charger.
I did note that with 18650 cells, a strong enough force from the side can knock one of the chargers out of it's bay within the cover. I don't expect this to happen with normal use.
Inside, the spring-bar at the bottom takes up the length for shorter cells. The positive contact has a small point on it to ensure compatibility with flat top cells. There's a molded indicator in each bay showing the proper cell orientation.
The sides are fairly featureless except for the singular switch and a small slot to make it easier to remove the cover.
The top of the charger is the exciting bit - a USB-A port marked output, and USB-C marked input. Note that the "input" port can actually be used for either input or output.
Finally, the back of the charger has all the specifications and regulatory markings silk screened.

What's Included

The charger comes with a USB-C to USB-A cable, which will be handy if it's your first USB-C device.

Charging

Display and Interface


The display is a bright LCD with white segments on my sample, though some other early samples had a red display. It's bright and highly legible. When charging, the display shows the percent charge of the two cells together, and the input current and voltage. Pressing the switch cycles to display the voltage and charge rate for each of the two cells, one at a time.
When being used as a powerbank, the display shows the percent charge remaining, the output voltage and current, and the port in use.
The standby drain on a single cell was measured at 0.17 mA, which would take a very long time to drain the cells.

Charging

Charging is straight forward - plug any USB-C cable into the port, and the charger charges the cells inside.
Charging from a 9V power supply, the resistance added by the measurement equipment caused a lower charge rate to be used, and the CC portion is a bit noisy, but nothing concerning. Two cells were completely charged in about 4 hours, which is impressive and convenient for a power bank.

Power bank

Increasing the current by 0.1A every 30 seconds shows the power bank will happily deliver more than the rated 2.0 amps from the USB-A port - the voltage started to drop 2 cells at 2.7A. Over current protection kicked in at 3.0A.
A 2A load on the USB-A output was powered for almost an hour from two cells. Output voltage remained stable for the test.
From the USB-C port, the output is similarly stable.
Testing the discharge and charge from both ports at around 2A gives us an idea of the efficiency - 73% for USB-A and 74% for USB-C. This makes perfect sense. The 5V USB input is being stepped down to charge the 3.7V cells, and 3.7/5 is 74%. That shows that there are charging losses due to the linear converter, but otherwise the powerbank is quite efficient. The charging losses shouldn't be a huge issue for most people plugging into a wall outlet.
The powerbank will stop charging a device when the current drops somewhere around 25mA. For charging devices at even lower currents, hold the switch until the display starts to flash. I tested a 10mA load and left it running for over 16 hours, and the powerbank kept delivering power.

Summary

Pros:

  • Fits 2 18650 or 21700 cells, and isn't picky about their length
  • Dual outputs is a nice addition for a power bank of this size
  • Fully enclosed - this is mandatory for anything I want to be able to chuck in a bag with cells installed
  • USB-C fully supported for input and output
  • High voltage outputs available
  • Descriptive display
  • Low current mode

Cons:

  • Smaller cells can be knocked out of place with enough force
  • Support for larger 21700 cells means the body is larger than the original PB2

Notes and Links

This product was provided free of charge from the manufacturer. I was not paid to write this review, and have tried to be as unbiased as possible. All charging measurements were recorded with version 2.0 of my measurement setup, or some variation of it.
Manufacturer's product page
HKJ's review with detailed measurements

Comments

  1. This comment has been removed by the author.

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  2. A very useful and concise review. What PD adapter did you use to charge the PB2S? Did it charge while 2 cells are inserted at 12 volts? I have 2 USB-A adapters, which both support QC3. One will always charge 2 cells at only 9 volts, which I assume is normal. However, the other will charge them at 12 volts every time, which results in getting lower Wh, which gives you a higher efficiency.

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    1. I used an XTAR PD wall adapter. I only saw it go as high as 9V with two cells.

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    2. Thank you very much for the reply.

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