There's a serious problem with this powerbank - not sure if it's just mine, or a fundamental design problem.
By Julian
Youtuber, shed dweller, solar charge controller aficionado
Good morning all…
Youtuber, shed dweller, solar charge controller aficionado
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Mine does not generate audible sound like yours. On the other hand, the output voltage of mine is having a 0.1 V fluctuation regularly which can be seen from the voltage curve on my YZXstudio USB monitor.
Julian, the "Brand" printed on the cover is actually a Chinese Character "七电”，it is NOT "tese" 😎
Could be the filter cap on the board has too small a capacitance or is an unlucky high ESR beast that skated through QC. SMPS's end up dropping to lower osc frequencies when the think the load is too high, that is, not enough output capacitance.
recently found your channel… even more recently subscribed… informative vids you made…
i just got mine (i have ninja postmen…so i had to collect from post office), and so far no high pitch squeal…
shame i could not get samsung 32A 18650 cells cheaply…
Julian, did you test the Power Bank with 1 amp or less?
Hi, mine does not beep and works fine.
I noticed 1 thing here your bank show 4v too… mine one shows
5v and 5.5v or till 13v max up not less then that displays. ..maybe you should return and replace. .. I can make video review too but I dont have machine for test like you… but sure there no noise in power bank and I am quite satisfied with that…thanks hope my little information can help you…
I am using this and its work fine can charge my note 3 in 2 hour full… but I dont have that machine to test.. but no sound in my bank
just add cap on the output I think that sound will go away
Inductor has definitely too little inductance for 10kHz. Sadly we can't see the driver name, but most of them with 8 legs and more have a resistor which sets the operating frequency. It could be a simple mistake of soldering the wrong resistor. We made that mistake in the past and had to manually replace few thousand resistors. It was just wrong label and pick&place guy didn't double check the original label.
I suspect that electrolytic capacitor is across the output and is completely unable to handle the ripple current. The voltage control loop is cycling the pulse operation on and off for every pulse (the overshoot for one pulse exceeds the maximum output voltage), instead of smoothly changing the duty cycle over many pulses. I would try paralleling the electrolytic leads wth a several microfarad of ceramic capacitor, as a diagnostic. I have a whole reel of 4.7uF, 25 volt, X7R units for this sort of thing. I'm betting one of those will completely change the output waveform.
Judging from the number of your power banks you should also have a pretty good number of 18650s. Could you do a buyer's guide video? I've read that eBay is full of scam batteries
Guys, do yourself a favour and order a bunch of BZW06-5V8 transit diodes and solder them over the USB output. I've seen these things go bad and damage a phone. Luckily not mine but the owner was not happy that some switched car adapter went bad. This could have been prevented by spending a couple of pennies on that transit diode.
Looks like some kind of feedback problem with the step up converter.
Can be caused by lots of things, including bad caps.
You could check the battery voltage on the pcb witch an oscilloscope, there should only be a small ripple voltage.
One pin of the inductor is connected to the usb output, measure the waveform of other pin of the inductor , there should be a pwm signal, probably it is modulated with the 10 kHz signal you measured.
a bad cap is my guess
BFH fixes everything
Batt contacts would be my guess. we use those power banks for e cig mods and the contacts are horrible.. I woulda said caps but it should be like the rest no measurable freq or in the 6 figure range but when batt contacts/connection are bad they get to squealin and low freq output.