Charger Skilhunt M4D
Skilhunt usual sells flashlights, but has recently started on chargers. This charger is a universal 4 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 lots of information on.
The box contains the charger, a power supply and a instruction sheet.
The charger has a barrel connector for 12V power input and a usb output connector for power bank function.
The user interface is a display and a single multi-function button.
Fast presses on the button will change the display between hour:min and capacity display.
Holding the button down for two seconds will change the current one step (300/500/700/1A) for all slots.
Holding the button down for 5 seconds will select LiFePO4 for all slots.
First display shows normal charging with 300mA, one LiIon and two NiMH cells.
The second displays shows that the power bank function has been activated (it will not stay on).
The charger uses the common slider construction and will handle batteries from 31 mm to 71 mm, this means just about any cell.
The charger exist in both the usual black and a sand colored one.
Measurements
- Discharges LiIon batteries with 34mA when display is on and not connected to power.
- Discharges LiIon batteries with 0.7mA when display is off and not connected to power.
- Discharges NiMH batteries with 0.1mA when not connected to power.
- Charges LiIon batteries with 0.4mA when connected to power.
- Charges NiMH batteries with 2mA when connected to power.
- Will restart charging if voltage drops below 3.9 volt.
- Charger will restart charging after power loss, or battery insertion.
- Voltmeter is frozen when charging is finished.
- Voltmeter is withing 0.04 volt on LiIon range (Current=300mA).
- Voltmeter is withing 0.01 volt from 0.95 volt to 1.5 volt.
- With 0 volt on a battery the current is about 2.3mA, enough to reset protection.
- At about 0.5 volt battery voltage the charger will reconize the battery
- Above 2 volt the charger assumes LiIon.
LiIon
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This looks like a good CC/CV charge curve with 100mA termination.
Display shows 2737mAh
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The other 3 channels looks just as good.
Display shows 2749mAh, 2785mAh, 2653mAh
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These two cells are also handled fine.
Display shows 2418mAh, 2878mAh
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The older cell is no problem, but do, of course, take longer to charge.
Display shows 1956mAh
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Here I am using 0.3A charge current, but the termination is still at 100mA, this is not ideal.
Display shows 2346mAh
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The smaller cells charge fine at 0.5A, but I would have like a lower termination current.
Display shows 551mAh, 665mAh
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All four channels charging at 1A, works nice.
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Charging four LiIon cells requires nearly 2A from 12 volt.
M1: 38,9°C, M2: 40,8°C, M3: 40,4°C, M4: 39,2°C, M5: 40,2°C, M6: 43,7°C, HS1: 56,8°C
Some heat is generated at 1A charge current, but not too much.
The charger is fairly fast to start and when powered on it will always start with lowest charge current.
Charge current can be changed at any time, just hold down the button for about 2 seconds to select next current.
LiFePo4
Holding down the button for 5 seconds will select LiFePO4 mode for all slots, it is possible to change current.
When finished charging LiFePO4 cells the display will flash as a reminder to remove the cells.
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This is a good LiFePO4 charge curve.
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The AA sized cell is also charged good, but again I would have like a lower termination current.
NiMH
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It looks like the charger terminates on voltage and may be a little bit early, but not much.
Display shows 1981mAh
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The same on the other slots.
Display shows 1801mAh, 1991mAh, 1912mAh
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On the XX a very small temperature raise can be seen, Pro has more temperature raise, i.e. they are full.
Display shows 2561mAh, 2659mAh
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This cell is getting old and it is very hard to terminate correctly, the charged missed termination and filled 9000mAh into the cell.
Display shows 9285mAh
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A low current charge cannot terminate on -dv/dt, but because this charger uses voltage termination it terminates fine and soon after the cell is full.
Display shows 2018mAh
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The AAA cell do also look fine.
Display shows 718mAh
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Terminating on voltage, it can detect a full battery very fast.
Display shows 28mAh
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Four cells at 1A is handled just as fine as one cell, except everything gets a bit warmer.
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Charging four NiMH batteries requires about 1A from 12 volt..
M1: 41,5°C, M2: 43,5°C, M3: 43,0°C, M4: 40,7°C, M5: 38,3°C, M6: 44,9°C, HS1: 61,7°C
Again about 4 seconds in startup time.
The current can be changed at any time by holding the button down for about 2 seconds.
With NiMH the charger turns the current off to measure voltage.
Power bank
- USB output is coded as Apple 1A.
- USB output is off when power is connected.
- USB output will turn off in 10 seconds when load is below 85mA.
- The power bank uses all mounted batteries.
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The usb output can maintain voltage to a bit above 1A and the overload protection will kick in at about 1.4A
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With more batteries in the charger, the output voltage is maintained to a higher current, but the overload protection is the same.
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With one battery the power bank output looks very good at 0.5A load.
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But totally hopeless with 1A load.
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Using four batteries for 1A load will help, but it is not perfect.
Note: My efficiency curve is not valid, battery voltage and battery current is only for one of the four cells.
The noise is very low at 0.5A: 6mV rms and 65mVpp
With a fresh battery it is also very low at 1A: 8mV rms and 80mVpp, but as can be seen above the output gets unstable when the batteries runs down.
Testing with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems.
Conclusion
The charger is good at LiIon including LiFePO4. Generally it also do a good job on NiMH.
The power bank function only works for low current charging, I wonder why it uses the Apple 1A coding, even Apple has switched to usb charger coding for 1A.
As a charger I will call it good.
Notes
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 and chargers
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
It has sand color, kinda cool when the other only got black and white.
Thanks again for your review HKJ
This looks pretty good, displays information on all slots at the same time and does 4×1A charging. The price is a bit eeeeh though. I’m receiving a Liitokala Lii-400 in the mail tomorrow that looks like a very similar, if not identical to this and I’m wondering whether that will perform similarly (I’ll have to hook-up my UT71D on it).
Speaking of which, what software do you use to make the graphs? They look beautiful and it seems perfect for such usage (electronics etc).
Use the code on my website to get a better price.
http://www.jfree.org/jfreechart/ controlled from my software.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Does it have any temp sensors?
The box does mention over-heat protection.
Not anything visible, but there may be something inside.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Mine,
When I charge left and right side slot of 26650s , no space for 18650s in middle slot like VC4
When charging is finished, information has gone , I can’t see information after charging is finished.
I did not have any problems with that, all the mAh was first written down after the charger had finished.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
I just want to confirm.
The information is only gone when the battery is removed right?
That was the way it worked when I tested.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Before : both 4.0V , Just finished then take a pic,
May be I use wrong slot to charge?
What do you mean POK?
whats wrong with the picture?
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Just finished. changed slot.
No display information , just finished charging.
I see, so the battery on the left isstill charging and the one on the right is finished?
This is an interesting charger but it has a few flaws that makes it imo a pass.
The nimh charging doesnt seem up to par, the defaut charging at 300mah is too low (it should be 500mah imo) and the fact that it stops displaying the info once a battery is full (weird).
It is fairly normal to start at the lowest current setting in chargers with multiple charge current. This charger can terminate a NiMH charge at low current, i.e. there is no problems with it.
And as I have already written: I did not have that problem.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
POK based on wha HKJ said you might either have a defective charger or a bad battery.
Did the charger do the same thing with the other battery when it completed charging?
I din’t test more yet, maybe protect PCB batteries problem.
I've discovered this charger on your website HKJ, it seems to be very good for all batteries, perhaps the best critics you have written.
I was surprised with the unique button but finally, it seems that's not boring. Does it choice automatically the current for the chemistry? Or does it push the lower one? What is the interest to choice LiFePO4 for all slots?
Thank you HKJ, good job
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The single button is easy to use, but a bit slow when you want to select 1A charge current.
The charger do always start at the 300mA setting when powered on, changing batteries will not change current.
I am not sure what your question is.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
For my 2nd question, I don't know very well LiFePO4 but I've thought they have not the maximum charge from the other Li-ion batteries, 4.1 V perhaps instead of 4.2 V?
I've seen the Skilhunt can't do any discharge or refresh
. Nothing is perfect 
. Then I'm wondering if I buy it or no.
I don't understand why I don't receive notifications for response while it seems to be good in my dashboard
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LiFePO4 is 3.6 volt maximum when charging and will usual drop 0.1 to 0.2 volt when the charging stops.
Correct, it is not a analyzing charger.
Because BLF has just been moved to a new server and configuration is not finished yet http://budgetlightforum.com/node/44795
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Ok for LiFePO4, that's why it's necessary to configure specifically the charger.
Have you in memory a 4 channel charger with dashboard display which is good and complete? I read your website regularly but I don't remember I've see one
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Ok for the forum. As I'm not easy in English, I don't come often on the forum and I only try to read the subjects which interest me.
Some questions HKJ, I can send you private messages but it can interest other guys : On your website, is it possible you write the date of the chargers tests on the main page? Thus we can find quickly the latest additions
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I've red a Li-ion battery doesn't be discharged under 3 ~3.1 V and charged above 4.2 V but on this test, you said that you wish the charger goes over 4.2 V. On Fasttech website, in batteries specifications, we can see batteries whose lower charge is 2.5 V and upper charge is 4.35 V. Are they more efficient or is it dangerous for the batteries?
Thank you
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Check the SkyRC MC3000, but it is rather expensive.
On my website everything is listen in chronological sequence, you can also look at the “Last additions” on the front page, it list all my reviews for about the last month (Again chronological).
The voltage some people says are only guidelines and often misleading. The low voltage from a LiIon battery is very depend on load, taking a battery out of the equipment and measuring with a DMM is unloaded voltage and can be more than 0.5 above loaded voltage, when battery is close to empty!
Most regular LiIon batteries has a upper limit of 4.20 volt, but some special types are made to handle higher voltage (4.30 volt and 4.35 volt). Before charging to these voltage you must now that the cell is designed for it!
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
I've begun to read the test of the SkyRC but I've stopped because it seems to be complex with a lot of possibilities and the test is very very long (as I said, I'm not easy in English). I try to maintain as well as possible my batteries but I have many other hobbies
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Ok for the chronology, I've noticed that the last ones are on top (but we don't know when you did them).
Sorry, can you explain? I don't understand.
Do you think that Fasttech specifications come from the manufacturer and thus are true? For example :
https://www.fasttech.com/products/1420/10001980/2204400-authentic-panaso...
And I've seen that these batteries have the same reference but are not same :
https://www.fasttech.com/products/1420/10001980/2204400-authentic-panaso...
https://www.fasttech.com/products/1420/10001980/2741006
It's a little disturbing.
You do not need a super smart analyzing charger to use batteries.
Battery charger reviews are done once a week (I wonder how long I can continue with that, before I run out of chargers).
When somebody says minimum safe voltage is 3.6 volt, they do not say how they measured that. When the battery is in a turned on flashlight 3.0 volt is safe (And often also lower values). When you take the cell out and measure it, the voltage may be 3.6 volt for the same battery that was 3.0 volt in the light.
In this article I measure some voltages with and without load: http://lygte-info.dk/info/BatteryChargePercent%20UK.html
Fasttech just copy the specifications they get from their supplier and not all supplier are careful with the specifications. (Panasonic do not supply batteries directly to Fasttech or any other outlet for loose cells).
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Yes I want a charger that charges as well as possible different batteries, refresh Nixx batteries and incidentally can say me what is the battery capacity. Thus it must have a discharge capability and this Skilhunt haven't.
There are a lot of charger brands, then I think there is regularly new models. Perhaps you will be tired before the stock will be exhausted
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I thought minimum and maximum charges were done with the battery out of the lamp.
With the same lamp charger, the first Ultrafire I got are stopped at 4.2 V (measured out of the charger) and the new ones stopped at 4.35 V (out of the charger), which was surprising and perhaps annoying.
With the first lamp I bought 4 years ago, the lamp stops when the battery have 3 or 3.1 V (I don't remember exactly, and measured out of the charger) and with the new lamp, the batteries were at 2.85 V (measured out of the charger) and have not stopped. I didn't try to know where it can go down.
LiitoKala Lii-500 or Opus BT C3100 are the usual choices, they handle all the common batteries.
The selection get a bit limited when I ignore chargers that looks the same and expensive charger and I must be able to buy them without paying a high shipping fee (last from a US dealer was $50 for shipping).
The above restrictions do not apply when somebody give me chargers to review
No normal LiIon is supposed to go above 4.25 volt (But it might be a good idea to replace the battery in your DMM).
3 or 3.1 volt do not really match anything, if it had been 3.3 to 3.6 volt if would probably be LiFePO4
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Ok I've red the capacity test and if I understand the first graphic (discharge test), for the other...
For the second, does it means the battery lost ~0.5 V in 25 hours when the battery is out of a lamp or a charger?
For the graphics with "With load, 10 s, 30 s... 60 mn", I don't understand at all. Is the red curve represents the charge when you measure the voltage immediately after you stop the flashlight and 60 mn the voltage after 60 mn of rest (battery out of the lamp during 60 mn)?
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