Test/Review of Charger Skilhunt M1

HKJ

Flashaholic
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Mar 26, 2008
Messages
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Location
Copenhagen, Denmark
[SIZE=+3]Skilhunt M1[/SIZE]

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Skilhunt usual sells flashlights, but has recently started on chargers. This charger is a universal 1 channel charger that can handle multiple chemistries and battery sizes. It does also work as a power bank.



I got the charger in a cardboard box with specifications on it.

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

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The charger is powered from micro usb and has a full size usb connector for power bank output.

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The charger has two red leds to show selected current and four blue leds in a row to select voltage and show battery level.
The button has multiple functions:
When a battery is put into a powered charger, it can be used to select LiIon voltage (NiMH is selected automatic).
When charger is powered a long press (2 seconds) will change between 0.5A and 1A charge current.
A fast click when charging will show the selected battery type.
When used as a power bank a press on the button will turn the usb power on.

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The charger uses the typical slider construction, it can handle batteries from 33mm to 70mm.

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supportedBatterySizes.png
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The charger can handle 70mm long batteries, inclusive flat top cells, this means most protected cells.



[SIZE=+2]Measurements charger[/SIZE]


  • LiIon and NiMH Batteries will be discharged with 0.1mA when power is off.
  • Charges LiIon batteries with 0.5mA when connected to power.
  • Charges NiMH batteries with 2.2mA when connected to power.
  • When battery is 0 volt the charger will charge with 3mA, this is enough to reset a protection.
  • From 0.25 volt on the battery the charger will reconize it and start charging.
  • Between 0.25 volt and 1.6 volt a battery is assumed to be NiMH.
  • Between 1.6 volt and 2.2 volt the charger will charge with less than 2mA and not allow selection of battery type.
  • Above 2.2 volt a battery is assumed to be LiIon.
  • Charger will not restart if battery voltage drops.
  • Charger will restart charging after power loss, or battery insertion.


[SIZE=+1]Charging 4.20 volt LiIon[/SIZE]

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The charger has a fine CC/CV voltage charge curve, it starts reducing current a bit early, due to voltage constrains, this will give slightly longer charge time.

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No surprise on these two cells.

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Reducing the charge current to 0.5A works fine, except the termination current is not reduced (Cells will miss the last few percent of the charge).

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With this older cell the current reduction starts very early as expected.

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Good charging on these smaller cell, again the higher termination current means a few percent loss in capacity.

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Adding a resistor in series with the usb power supply to simulate a long cable or weak supply did not prevent the charger from doing a good job, but it needed some more time.

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M1: 35,1°C, M2: 37,7°C, M3: 44,4°C, HS1: 48,3°C

Temp2787.png


M1: 34,4°C, M2: 35,0°C, M3: 38,6°C, HS1: 50,5°C

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The charger needs some time to start up, this is because it is waiting for voltage selection.

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There is no problem with changing current while charging.



[SIZE=+1]Charging 4.35 volt LiIon[/SIZE]

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The 4.35 volt charge works as expected.



[SIZE=+1]Charging 3.60 volt LiIon[/SIZE]

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Both LiFePO4 cells is charged fine, but the voltage is a bit high (This is not a big problem with LiFePO4).



[SIZE=+1]Charging NiMH[/SIZE]

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This is a good NiMH charge with -dv/dt termination and no trickle charge.

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Using 0.5A charge current the -dv/dt signal is nearly gone, but the charger do termination when the battery is full.

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On this cell it looks like a voltage termination.

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Here it is again a -dv/dt termination.

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This cell is nearly hopeless to termination on, but the charger did stop.

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The AAA cell is stopped on voltage.

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Fast detection of a full cell, this is voltage termination.

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M1: 33,7°C, M2: 40,0°C, M3: 31,9°C, HS1: 49,6°C

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The charger is also slow to start with NiMH, but it is not possible to select any other battery type.

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There is no problem with changing current while charging. The charger uses the typical pulsing, where it can measure voltage with current off.



[SIZE=+1]Power bank[/SIZE]


  • USB output will turn off after 10 seconds with less than 63mA load.
  • When input power is applied, usb output will be off.
  • Mode button can be used to turn usb output on.
  • USB output is coded as usb charger (DCP).

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USB output can deliver 1.3A before it starts dropping, the overload protection first kicks in at 2A.

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Running with 0.5A load looks very good.

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Increasing to 1A do have some problems the last 5 minutes, but generally works fine.

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The noise is fairly good at 0.5A load with 21mV rms and 200mVpp

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At 1A the noise increases, but is still acceptable with: 40mV rms and 310mVpp



[SIZE=+2]Conclusion[/SIZE]

The charger is not perfect, it has a few small issues, but nothing serious with any of the functions.

This makes it a good charger for all supported batteries and also a good power bank.



[SIZE=+3]Notes[/SIZE]

The charger was supplied by Skillhunt for a 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/charger
 
Last edited:

ChrisGarrett

Flashlight Enthusiast
Joined
Feb 2, 2012
Messages
5,629
Location
Miami, Florida
A good single bay USB charger/power bank that can handle all the common li-ion cells that we might see.

To be better, a 250mA rate would be desireable, but if you're using this charger in a crisis, I don't think you'd be too concerned about stressing some of your smaller cells with the 500mA rate.

Thanks,

Chris
 

light-wolff

Newly Enlightened
Joined
Jun 16, 2013
Messages
113
Location
Southern Germany
To be better, a 250mA rate would be desireable, but if you're using this charger in a crisis, I don't think you'd be too concerned about stressing some of your smaller cells with the 500mA rate.
It can be modified quite easily for 0.25/0.5A charge current instead of 0.5/1A. Only one resistor to change. There's a thread about this on BLF.
And while it's open, one can also fix the systematically higher-than-perfect charging voltage by modifying another resistor.
And if the USB output voltage is a bit low on your example (as it was on one of mine: 4.95V): there's also a resistor fix to that.
I like this charger for its moddability :)
 
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