Test/Review of Charger Xiaomi ZI5 PB400

Batteries and Chargers Chargers
1

Charger Xiaomi ZI5 PB400











This is a very small 4 channel NiMH usb charger with power bank functionality.







The charger comes in a white cardboard box whith some low contrast Chinese writing on it (Probably specifications).







In the box is the charger with a lid and a usb cable (micro to USB-A).







The charger has two connectors:

Micro usb for power input, it requires 5 volt 1A.

The large usb connector is for power bank output.

Selection between charging battery and working as a power bank is done with a switch.







There is some specifications on the charger.







Each slot has a small white led behind a small hole.

These leds are flashing slowly when charging and steady lit when the battery is full.

When working as a power bank the leds lights up in turn at a slow speed.











The charger uses the typical two level slots for AA/AAA cells.













Measurements

  • When not connected to power it will discharges with less then 1uA

  • Power cycling or reinsertion of the battery will restart charging.

  • Power consumption when idle is 20mA or 0.1 watt from usb.

  • Power consumption when usb output is select with less than 4 batteries in the device is 2mA or 0.01 watt from usb.

  • Charging is only possible with switch in charge position.





The charger uses voltage termination with a one hour top-off charge. With this cell the main charge terminated before the cell was full, but the top-off filled the cell.





All 4 slot filled the batteries.





All 3 high capacity cells show temperature raise, i.e. they are all filled.



With AAA cells the charge current is only 250mA, again the temperature increase can be seen on the top-off charge.



With voltage termination a full battery is detected fairly fast, but ZI5 insist on topping it off with a one hour top-off charge.



With four battery the charge current is lower and the top-off charge takes two hours instead of one.
I have no idea why the charger takes a short break just before the batteries are finished.



The input current is pulsing and is at about 1A.



M1: 38,5°C, M2: 40,8°C, M3: 38,9°C, M4: 36,2°C, M5: 37,9°C, M6: 46,5°C, HS1: 50,1°C
For the compact size the charger is keeping the temperature well down.
Note: Testing was without lid.



M1: 46,3°C, M2: 39,7°C, HS1: 50,5°C



The charger needs less than 2 seconds to start charging, before that it checks the internal impedance of the cells (My 100mOhm scope adapter was too high). The charger uses 2.3A charge current in pulses. With one or two cells it is about 50% duty cycle



Here is the current drawn from the usb connector.



The pulsing is the same with two cells.



But the current draw has changed, now it need to draw current all the time, except when changing between cells.



With 3 cells the duty cycle is about 33%



And with 4 cells it is about 25%.



With all four cells the current pulses and pauses are fairly constant.



The top-off charge is done with lower current.



USB output

  • USB output is coded as usb charger (DCP)

  • When usb output is active it will drain about 5mA from the batteries.

  • All 4 batteries must be mounted for usb output to work.

  • Batteries are in series when powering usb output.

  • USB output will only be on when switch is in usb output position.




The usb output is not very powerful, only 0.6A.



0.5A output current can be maintained for nearly 3 hours.



There is 47mV rms noise and 225mVpp noise.



Letting the scope do a spectrum analysis shows that the main switching frequency for usb output is about 300kHz.



Conclusion

It is a good charger and with the compact size it can easily be used as a travel charger, especially if you are hauling other usb equipment. Charge time is good with one or two cells and acceptable with 3 or 4 cells, but you have to manually add two hours if you want to be sure the batteries are completely filled.

As usual I am not impressed with NiMH based power banks (4 AA battery is about the same power as one 18650 battery), but with this compact charger it is a nice extra, even if the usefulness is a bit limited.



Notes

The charger was supplied by Gearbest for review.

Here is an explanation on how I did the above charge curves: How do I test a charger

Read more about how I test USB power supplies and chargers
2

Dear HKJ,

Thanks for this excellent review.
As far as I remember some of the 4xAA power banks are capable to use primary batteries (alkaline and lithium). This can be useful in emergency. Have you tried this option?

3

No, I have no doubt it will work, the question is for how long. The current consumption will be between 0.5A and 1A, my guess is that they batteries will last about 1.5 hour.

4

At first: thank you again! I had strange feelings, ordering that charger, without knowing, what you say about it. I just charged my first batteries with it, as I saw your post. :slight_smile:

How full are batteries, when LED changes to steady light? and how useable is that charging method for Eneloops (over 90% of my batteries)? Topping charge isn’t any intelligent, if I got this right.

I like the charger for travelling, it weighs almost nothing, works with USB, is small and not very expensive. I wished, it would indicate, when charging is completely done.

5

Four Energizer L91 batteries at the specified current should last significantly longer than 4 AA NiMH.

6

They will, Lithium can handle some current, they can deliver about 3Ah (3000mAh) at 1A.
http://lygte-info.dk/review/batteries2012/Energizer%20Ultimate%20Lithium%20AA%20UK.html

7

So for someone that has an Xtar single-bay charger that only accepts Li-ion and no other “portable” charger, would this be a good buy?

I’m gonna have to see if they have a 2-bay version. That would be awesome.

8

For anybody that need a portable NiMH charger this is a good buy (The lid can be discussed, I am not going to use it).

The 4 bay version is rather small and light weight.

9

How does voltage termination deal with half-filled cells? Will the voltage peak of the cell happen at the same state of charge regardless of state of charge at the start of the charge?

10

It will. The major problem with voltage termination is that the actual voltage varies with temperature and cell chemistry and if the termination voltage is just a bit too high the charger will miss termination. The solution is to place the it too low and follow it with a top-off charge.

11

Thanks. Personally I’m very happy with how my LiitoKala Lii-400 does dV but I guess that’s more complicated to implement (needs a more expensive microcontroller maybe?)

12

-dv has advantages and disadvantage. I did write a bit about the different charge methods here: Battery Charging NiMH

13

How would this charger compare with the classic Eneloop BQ-CC17 for charging Eneloops and similar batteries? Is the top-off charge an advantage or disadvantage?

I like that it charges from USB and maybe I can even sometimes use the powerbank feature, but would it be a good replacement for the CC17?

14

It is difficult to say what is best.
CC17: Fills the batteries, then stops and reports ready.
PB400: Nearly fill the batteries, reports ready, add a fixed amount more charge during the following 1 or 2 hours.

The PB400 is fastest and when it reports ready you can use the batteries.

I prefer the PB400 for my usage.

15

Being faster means it charges with higher current - isn't that a bad thing for the battery lifetime? Isn't there a reason why 1900/2000 mAh Eneloops that are rated for up to 2100 recharge times come with the CC17 that charges them at 300 mA, and this is the best charger they make for them? On the other hand, the 2500 mAh ones, that are rated for up to 500 recharges, usually come with the BQ-CC16 that charges at 550 mA.

16

Depends on how fast, charge times above 2 hours are not really fast.

I believe that is more marketing, than technical related.

17

There are bundles of normal Eneloops with the BQ-CC16 (e.g. http://eu.nkon.nl/charger/nimh/panasonic-eneloop-bq-cc16-quick-charger-with-4aa-eneloop-batteries.html )

18

Lets suppose you cut 2100 cycles to just half that (550mA would not cause this) and you charge each of your cell once a week per average. That would give you over 20 years of useful lifetime. By that time there will be some- teenth generation eneloop on the market or some kind of completely new technology so even if you could, you probably won’t like to use those old eneloops anyway… You will lose them faster than that :smiley: So I would not worry about eneloop lifetime at all provided you use some half-decent charger.

19

apparently they are not producing this model anymore… I can only found this one without the USB output (It doesn’t even seem a genuine xiaomi actually, first time I see that kind of packaging)

https://www.gearbest.com/chargers/pp_009490858950.html?wid=1433363

https://www.aliexpress.com/wholesale?SearchText=zi5+charger+xiaomi&ltype=wholesale&d=y&tc=af&blanktest=0&initiative_id=SB_20180817140905&origin=y&catId=0&isViewCP=y&jump=afs