Charger Woyum ZK6





This is a 6 slot NiMH charger with a nice display and it is usb powered.



I got the charger in a cardboard box.



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



The charger is powered from usb



Each slot has a red/green led, that will show red while charging and green at all other times.



The charger can show 3 values for each cell, here it is charged capacity.
The circle peripheral is animated while charging, the dial and short arc shows the selected cell.



Cell voltage.



And time. It will change between them for the selected slot.
A single press on the button will move to the next slot, this sequence will always include all 6 slots, i.e. also empty slots.



A double click enters current configuration for that slot. The current is changed with single clicks between 300, 400, 500 and 1000mA.
The response when clicking is a bit slow.




The charger has the typically two level slots used for AA and AAA batteries.







Measurements charger

• Power consumption when idle is 15mA from usb.
• Voltmeter shows 0.01V, but actual resolution is about 0.07V
• Voltmeter is within 0.08V
• Charger will start charging at about 0.55V
• Charger will discharge batteries with less than 0.1mA when not powered
• Charge will restart charging after power loss, or battery insertion.

This is a classic -dv/dt charging and termination where the cell gets a bit warm at the end.
Display shows 2103mAh in 2:26



Display shows 2152mAh in 2:32



Display shows 2062mAh in 2:25



Display shows 2179mAh in 2:34



Display shows 1968mAh in 2:09



All the slots looks about the same.
Display shows 2143mAh in 2:22



Display shows 2705mAh in 3:12



The two high capacity cells are also handled nicely
Display shows 2712mAh in 3:12



Using the lowest charge current slows down the termination, but the charger do terminate.
Display shows 2157mAh in 9:22



The AAA cell looks nice.
Display shows 748mAh in 1:50



Usual the charger will automatic select current, this time it selected 300mA (My current sensor adds some resistance making the battery look older).
Display shows 2087mAh in 9:06



A full battery takes some time to detect when using -dv/dt, here it is done in 14 minutes, this is fairly fast for this type of charger.
Display shows 201mAh in 0:14



With 6 batteries it need about 1.5A from USB power.





With 4 batteries at 1A the current is 1.8A from USB power.
Display shows 2068mAh,2089mAh,2092mAh,2195mAh in 2:27,2:26,2:27,2:37





M1: 47.4°C, M2: 43.4°C, M3: 40.7°C, M4: 37.7°C, HS1: 65.3°C
The charger gets a bit warm around the electronic, this is heating slot #1, especially at full power.
I would recommend when charging at 1A to use slot #3..#6 and leave #1 and #2 empty, this means cooler batteries (When charging 6 batteries the total current will be lower, this will probably also mean less heat).



M1: 45.4°C, HS1: 52.3°C



The charger needs a few seconds to start.



It is possible to change current at any time.



As usual with NiMH chargers the current is turned off to measure the voltage.



This charger do not like unstable input voltage, it may lock up and the charge current is slow to adjust.



Conclusion

The charger is charging NiMH cells fine and due to the current settings it can be used for older cells also. Using the 6 slots do not make the charger faster, because it will use a lower current, for the fastest charging up to 4 slots can be used.
The user interface is fine as long as charging current is selected automatically, but manually selecting current for a couple of cells requires a lot of button presses!

I will rate it as a good charger.



Notes

The charger was supplied by Woyum (Goeasy Charger Technology) for review

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