NEW XTAR PB2S Review – Supports Protected 21700’s


Pricing & Availability

XTAR has updated their PB2S model with some new features and they sent me this sample in exchange for an honest review. Here is the official Amazon page which is currently out of stock due to the Chinese New Year holiday, but will be available soon.

What comes in the box?

The packaging is basic but includes lots of text on the outside describing the charger. It also has a clear window to show the charger inside. The large “NEW” badge on the box distinguishes this from the old version. The following items are included in the box:

  • The charger itself
  • USB A-to-C cable
  • User manual

Design & Construction

The design is almost identical to the original PB2S. The only external change is the removal of the gross-feeling rubberized “soft touch” texture on the old version. As a result, the new version is much more pleasant to hold but its plain plastic finish picks up fingerprints and scratches much more easily.

Size & Measurements

MeasurementMeasured (mm)
Maximum battery length78.4
Minimum battery length63.6

Empty weight : 85g

User Interface

There’s one button on the side to control functionality. Basically all it does is activate the display and then let you cycle between the “output”, “bay 1”, and “bay 2” screens that show percentage, voltage, and current. You can only enter the “bay” screens while the charger is charging.

Output Screen | Bay 1 Screen


There are two ports on the end: a USB-C for in/out and a USB-A for output only.

Pass-through charging works great so you can daisy chain devices together. I connected it to a variety of devices and the only problem I had was when trying to charge a Sofirn Q8 Plus (flashlight that can also work as a powerbank) via a C-to-C cable, and neither device recognized the other so no charging happened either way. Switching to an A-to-C cable solved the issue.

I am not equipped to test all the various charging protocols but it did step up to 9V PD charging when connected to my smartphone, so I can confirm that that feature works.

Batteries & Charging

The big added feature of this new version is support for protected 21700 cells. The old version could only fit unprotected 21700’s (plus any variety of 18650). They accomplished this by extending the battery compartment slightly and adding a small removable spacer.

Spacer Removed | Spacer Installed
Spacer Removed | Spacer Installed

You can use any combination of protected or unprotected 18650 or 21700 cell except a protected 21700 and an unprotected 18650. In that situation the unprotected 18650 will be too short to fit.

New PB2S | Original PB2S

There’s also a little toggle inside the magnetic lid to help keep 18650’s from rattling inside. By default it’s in line with the batteries (to be out of the way) but it can be rotated 90 degrees and snaps in place. It can only be used if there are no 21700 cells installed inside the charger.

Some things to note:

  • Charging stopped at 4.21V per cell (and stayed there after being on the charger for 1.5hrs) which is acceptable.
  • Parasitic drain is 150-300 microamps. That’s higher than I’d like and you’ll have to be sure to recharge cells soon (within a day or so) after they’ve been depleted. If they’re fully charged that parasitic drain won’t be noticeable. For example, at that rate a fully charged Molicel P42A will last for 1.5-3 years.
  • My discharge test left one cell at 3.3V (molicel P26A) and the other at 3.17V (molicel P42A). It would not even power on the display at this point. Both of those are perfectly acceptable (if not a little too conservative) cutoff voltages.


There’s not really any direct competition here that I’m aware of. There are powerbanks, and there are bay chargers. This is the only product I know of that does both. There are some bay chargers with a power-out function, but I don’t count those as powerbanks because they’re bulky and cells are exposed and could fall out. I don’t want to throw one of those in my pocket or bag.

Note: I’m not counting previous versions (PB2, PB2C) nor rebrands of them (Astrolux BC2). If you know of any other legitimate competitors, please let me know!


PB2S was the only good charger + powerbank combo product on the market before this update. Now, it still is, and it’s a little bit better. The old one was my go-to powerbank and portable charging solution and now this new one will be my go-to.

Thanks to XTAR for sending me this light for review!

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