Test/review of USB LiIon Charger BH-042100-02U

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HKJ
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Test/review of USB LiIon Charger BH-042100-02U

USB LiIon Charger BH-042100-02U
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This is a cheap LiIon charger from Ebay, does it work?
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I got the charger in a envelop from Ebay dealer: buybtyhere
It included the charger and a thin USB cable.
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The USB power connector is placed on the back of the charger.
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The user interface is a led for each slot, it will show red while charging and green at all other times.
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The back has the usual label with specifications, but they are not very precise.
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The connection are the common slider style that can handle from 31.5mm to 69.5mm, this means a few protected 18650 will not fit and the new xx700 will not fit.
supportedBatteryTypes
supportedBatterySizes
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The charge current is on the high side for small batteries and of course the voltage is too high for all batteries.
Measurements charger


  • When not powered it will discharge the battery with less than 0.01mA
  • Charge always charges from a constant voltage of 4.316 volt on slot #1 and 4.286 volt on slot #2.
  • Led changes to green at 4.284 volt on slot #1.
  • Power consumption when idle is 5mA from USB

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The charging is a rather bad CC/CV charge curve around 600mA and the charger never terminates, instead it charges to 4.3V. The charge circuit goes into oscillations at one point during the charge (This is probably a combination of voltage and internal resistance of the battery and do not show up on my other curves).
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Slot #2 is similar, but it do not oscillate, it is slower to charge and have a lower termination voltage, but still way to high.
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I did not try with a lot of batteries, due to the high voltage. This cell was charged in a similar way to the above.
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Simulating a long cable or a weak charge do not affect the charger much
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The charger maintain same charge speed with two batteries.
Temp7040
M1: 34.2°C, M2: 35.2°C, M3: 44.5°C, HS1: 49.9°C
Temp7041
HS1: 45.6°C
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There is a constant current generator for each slot inside the charger, it will use a low current for fully discharged batteries.
Tear-down
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What is inside this type of cheap charger? The bottom was five screws and the circuit board was one screw.
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Not much on this side, only two dual color leds and the battery connection.
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Not much on this side either, only one unmarked chip for each slot. Each chip has two resistors and two capacitors.
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Conclusion
This is not a very good charger, the main issue is the high charge voltage and the secondary issue is that it never terminates.
Notes
The charger was supplied by a reader for review.
Here is an explanation on how I did the above charge curves: How do I test a charger

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/