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Thread: Test/review of Xtar PB2 Charger & power bank

  1. #1
    HKJ's Avatar
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    Default Test/review of Xtar PB2 Charger & power bank

    Xtar PB2 Charger & power bank





    This is a 18650 charger and power bank from Xtar.



    It arrived in a white cardboard box with a window in and some specification on it.



    The box contained the charger, a usb cable and a instruction sheet.



    The charger is usb powered with a micro usb input and a usb output for the power bank function.



    This button is used to turn the power bank on, this is only needed when checking the power level, it will automatic turn on when a load is connected.



    The display shows from 00 to 100, depending on how much capacity is in the power bank. While charging one of the digits will flash. When powered on or reset is will show a counting sequence: 00-11-22-33-44-55-66-77-88-99- for external usb power and 99-88-77-66-55-44-33-22-11- for internal battery power.



    The lid uses magnets, this makes it fairly easy to open when you stick you nail into a small slot. The magnets are strong enough that you can easily lift the box in the lid, when it is filled with batteries.










    This charger only supports unprotected 18650 batteries.



    Measurements


    • Power consumption from usb when idle with no batteries is 9mA
    • Will charge one battery with 2A
    • Will charge two batteries with down to 1A on each (Lowest voltage will get more current)
    • Will discharge a full battery with about 0.5mA when powered.
    • Will discharge a full battery with about 0.1mA when not powered.
    • Below 0.5V the charger will report error
    • Between 0.5 and 3V the charger will charge with low current (200-300mA)
    • Above 3V the charger will use full current.
    • Will not restart charging if voltage drops.
    • Will restart charging if battery is inserted.





    A nice CC/CV charge curve with termination around 100mA



    Second slot looks similar.




    These two other batteries is also charged nicely.



    With two batteries the charge current drops to 1A to keep the usb input current at 2A.



    Adding 0.5ohm resistance in series with the power supply to simulate a long cable or weak supply shows that the charger will reduce usb and charge current, but the charging works fine.



    M1: 34.6C, M2: 43.9C, HS1: 45.0C
    There is some electronic inside the charger that gets a bit warm, but the battery box do not look warm.



    M1: 37.2C, M2: 37.3C, HS1: 46.5C
    Batteries are below 40C while I am charging with lid on, this is fine.



    M1: 40.7C, HS1: 51.7C
    And the hottest part of the charger electronic do not look very hot.



    The charger is very fast to start, it only needs about 1 seconds.



    Power bank

    • Will discharge a full battery with about 0.1mA when not powered.
    • Usb output turns off after 45 seconds with load below 290mA, with no load it turns off after 10 seconds.
    • Usb input and output is not directly connected, no output voltage leaks to the usb input.
    • Cannot be used as a UPS, output turns off when usb power is removed.
    • Usb output is coded with usb charger (DCP)





    With one battery the charger is rated for 1A and overload trips at 1.3A, this looks fine.
    All load sweeps make a measurement at 0 then jumps to a bit above 300mA to avoid auto turnoff.



    With two batteries the rating is 2A and it can deliver a bit above 2.4A.



    With no batteries in the charger, but usb power connected it passes the power through, but there is some voltage drop.



    With one empty battery the charger will charge the battery, but keep the usb power draw at 2A, this is the reason for the low efficiency at low current.

    Below efficiency curve is only valid with one battery in the charger



    As a power bank it can easily deliver 0.5A until the battery is down to about 3.2V, where it turns off.



    Second channel looks the same.



    With two batteries the time is slight more than double up.



    One battery can also handle 1A load and the voltage stays stable (more or less) until the battery is empty.
    There is no overload protection here, charger depends on overload protection in the usb charger used to power it.



    With two batteries the time is again more than double.



    For 2A output two batteries are required.
    The output voltage jumps up and down on all the curves, but stays within the required usb range.



    There is 24mV rms noise and 287mVpp noise.



    There is 157mV rms noise and 405mVpp noise.



    There is 72mV rms noise and 869mVpp noise.



    Conclusion

    This charger and power bank has a good size for a two battery device and the magnetic lid is easy to open. The charging looks good, but batteries must be able to handle 2A charge current.
    The power bank has enough power to maintain output voltage, until the batteries are empty, the coding is also fine, but I could have wished for lower noise on the output, this jumping up/down in voltage may force some devices to a lower charger current.

    I will rate is as a fairly good power bank and charger.



    Notes

    The charger was supplied by XTAR for a review.

    Here is an explanation on how I did the above charge curves: How do I test a charger
    Last edited by HKJ; 06-01-2018 at 08:26 AM.
    My website with battery, charger, usb reviews, comparisons & information: https://lygte-info.dk/
    Latest addition is multimeter reviews

  2. #2

    Default Re: Xtar PB2 Charger & power bank

    • only supports unprotected 18650 batteries
    • Will not restart charging if voltage drops.
    • Usb output turns off after 45 seconds with load below 290mA, with no load it turns off after 10 seconds.
    • Cannot be used as a UPS, output turns off when usb power is removed.
    It looks like button tops won't fit either so it probably won't work with half the batteries people already have. It can't be used with a 5V solar panel. It can't be used with most USB nightlights. It can't even recharge common li-ion headlamps like the NU25 that average at 150mA of draw.

    This is disappointing. I was really excited about this powerbank. Having trouble thinking of more things they could have done wrong and I'm not going to recommend this to anyone for outdoors/backpacking.
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  3. #3
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    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by HKJ View Post
    • Below 0.5V the charger will report error
    • Between 0.5 and 3V the charger will charge with low current (200-300mA)
    I'm surprised that it blindly recharges cells that are as low as 0.5V - generally that is not safe.

    Did you check if there is a safety timeout in this precharge phase, e.g. does it stop precharging if the cell doesn't reach 3V in some short fixed time? Given that it may be doing unsafe charges such a timeout is crucial for safety.

  4. #4
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    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by Gauss163 View Post
    Did you check if there is a safety timeout in this precharge phase, e.g. does it stop precharging if the cell doesn't reach 3V in some short fixed time?
    No, I just run a voltage ramp from 0 to 4.2 volt in a few minutes (This test do not work on all chargers).
    My website with battery, charger, usb reviews, comparisons & information: https://lygte-info.dk/
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  5. #5
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    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by HKJ View Post
    No, I just run a voltage ramp from 0 to 4.2 volt in a few minutes (This test do not work on all chargers).
    So if we use samsung 25R-s with this charger , we should be ok?

    Ps you should review more 18650 battery banks, a lot of us have issues finding a good one,
    Apparently now you can find on some sites with box chargers that look almost identical to your ENB battery box that you reviewed,
    but we dont know if its just a similar board case or maybe something completely different...

    PS , I love your reviews

  6. #6
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    Default Re: Xtar PB2 Charger & power bank

    [QUOTE=goa2000;5211776]So if we use samsung 25R-s with this charger , we should be ok?


    Yes.

    Quote Originally Posted by goa2000 View Post
    Ps you should review more 18650 battery banks, a lot of us have issues finding a good one,
    Apparently now you can find on some sites with box chargers that look almost identical to your ENB battery box that you reviewed,
    but we dont know if its just a similar board case or maybe something completely different...
    If you have some links to where I can get them I might help (Remember I am in EU), you can use my email or a PM (When you have a few more posts), it do not belong in this thread.
    My website with battery, charger, usb reviews, comparisons & information: https://lygte-info.dk/
    Latest addition is multimeter reviews

  7. #7

    Default Re: Xtar PB2 Charger & power bank

    Turns off at 3.2v. Seems a little high. I always wondered what other "sealed" powerbanks stop at, like the Anker and other popular brands.
    GOOD TINT!

  8. #8

    Default Re: Xtar PB2 Charger & power bank

    Just got mine. Good quality and light enough that I'll probably use this to charge my phone while backpacking instead of my old 5200mAh. Gained an extra 1800mAh for the same size using 18650GA cells, plus I can manually discharge them to about 50% when in storage since I'm not getting out on a weekly or even monthly basis.

    The display is hard to read in anything but the dark, but not a big deal.
    GOOD TINT!

  9. #9
    Flashaholic* peter yetman's Avatar
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    Default Re: Xtar PB2 Charger & power bank

    My PB2 arrived this morning. No thanks to who ever covers CPF for Xtar, I asked twice in the PB2 thread where I could get one in the UK and got no help.
    I found one at Cloudstix UK who delivered quickly.
    The PB2 has a nice soft texture that you won't mind in your pocket. It's about the size of a packet of 10 cigarettes so a good size, even if you just use it to carry 2 x 18650s. My display is nice and bright, so maybe you got a lemon, Mark.
    So far I'm a happy bunny, it does what it says on the box.
    P
    Last edited by peter yetman; 06-19-2018 at 03:45 AM.

  10. #10

    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by peter yetman View Post
    My display is nice and bright, so maybe you got a lemon, Mark.
    P
    That's the problem with all these kinds of displays (DROK voltmeter, etc.) They're so bright the light bleeds into the other slot. Another person mentioned this on BLF: http://budgetlightforum.com/comment/...omment-1331682

    I don't think mine is that bad, but like I said it depends on the ambient light as well.
    GOOD TINT!

  11. #11
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    Default Re: Xtar PB2 Charger & power bank

    I may have got lucky as my display is very clear indeed.



    It's actually clearer than my camera makes out.
    P

  12. #12

    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by peter yetman View Post
    I may have got lucky as my display is very clear indeed.

    It's actually clearer than my camera makes out.
    P
    Yeah mine is similar. Initially I see 92, but leaning towards 52. It's just not clear but what I would expect from this kind of display.
    GOOD TINT!

  13. #13
    Flashaholic* peter yetman's Avatar
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    Default Re: Xtar PB2 Charger & power bank

    When I use my PB2 to charge my Iphone, it cuts off when the phone reaches about 90%. I imagine this is due to the charger cutting out when the current draw drops.
    If I restart the charging I can get it to 100% with a couple of restarts. My Mophie powerbanks run it up to 100% first time.
    Would putting higher capacity cells in the PB2 make any difference? I'm using twp AW IMR 2200mah cells.
    P

  14. #14

    Default Re: Xtar PB2 Charger & power bank

    My first real test:

    Start
    Xtar: 98% (both 18650GA cells jumping between 4.18 and 4.19v on my meter)
    iPhone 6S: 40% (the lowest I typically decide to top off when backpacking)
    ~.9-1.05A current at the beginning, leveled off around 0.91A

    End
    Xtar: 67% (one cell at 4.07v, the other at 4.08-4.09v)
    iPhone 6S: 90% (I stopped here since I never have time/patience to do much more)
    Time: 1 hour

    Only 4 minutes into this and the Xtar shows 83%, so that scares me. Hopefully that will level off. I'll try not to use my phone at all while charging. While backpacking, I would typically turn it off or at least airplane mode. Update: after about 15 minutes it leveled off around 80% and decreased slowly from there.

    p.s. I decided to try and top my phone off completely. The Xtar stopped and turned off when my phone hit 94%. The Xtar was at 65%
    Last edited by markr6; 07-11-2018 at 12:31 PM.
    GOOD TINT!

  15. #15
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    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by markr6 View Post
    Only 4 minutes into this and the Xtar shows 83%, so that scares me. Hopefully that will level off. I'll try not to use my phone at all while charging. While backpacking, I would typically turn it off or at least airplane mode. Update: after about 15 minutes it leveled off around 80% and decreased slowly from there.
    Yeah, I find the Xtar PB2 doesn't give a very accurate capacity reading when discharging, at least at first. I believe that's because it's just reading voltage, and using that to approximate capacity. When you're discharging, there's a voltage sag, and the Xtar thinks that means a lower capacity. The Xtar is expecting a resting voltage, and gets messed up by the voltage under load.

    p.s. I decided to try and top my phone off completely. The Xtar stopped and turned off when my phone hit 94%. The Xtar was at 65%
    The Xtar does have a fairly high cut-off for current. Your iPhone is likely pulling too few milliamps from the charger when the iPhone is almost full, so the charger cuts off. I used the Xtar to charge a Samsung phone, and it charged it to 100%. I guess Samsung must charge faster, especially near the end. (The phone was off, so it wasn't drawing any extra current to run it.)

  16. #16

    Default Re: Xtar PB2 Charger & power bank

    Thanks for the info. I didn't have the USB tester attached when I was topping off the second time, so I don't know the current. Likely under 500mA since it was around that the first time towards the end.
    GOOD TINT!

  17. #17
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    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by markr6 View Post
    Thanks for the info. I didn't have the USB tester attached when I was topping off the second time, so I don't know the current. Likely under 500mA since it was around that the first time towards the end.
    You can press the side button to turn the charger on and it will then charge even low-current devices. The problem is that you have to keep hitting the button about every 15 seconds, so it's not very practical. I wish they had a "always on" feature, activated by a double-press or long-press of the button.

  18. #18

    Default Re: Xtar PB2 Charger & power bank

    I unplugged it and plugged it back in and seemed to stay on for at least 15 more minutes. I didn't bother waiting to get to 100% but I have a feeling it would have. Either way, I really like this for backpacking. It will certainly replace my older 5200mAh sealed pack.
    GOOD TINT!

  19. #19
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    Default Re: Xtar PB2 Charger & power bank

    It may not be perfect, but I like mine. The fact that I can pull out one of the 18650s if I need one, is the main positive for me.
    P

  20. #20

    Default Re: Xtar PB2 Charger & power bank

    Quote Originally Posted by peter yetman View Post
    It may not be perfect, but I like mine. The fact that I can pull out one of the 18650s if I need one, is the main positive for me.
    P
    Yea, since I use my H600w backpacking, I can pull that on the last day if necessary to get my phone charged some. I typically come home with a 1/2 full or better headlamp battery anyway.
    GOOD TINT!

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