Diy power bank noise problem

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Alen
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Diy power bank noise problem

I have bought a couple of these Cheap Power bank
http://www.banggood.com/Power-Bank-18650-Battery-Charger-Portable-for-Fl...

They works fine,cut-off charge battery at 4.17 volt and output about 800 Mah
But there is a problem when charging and at the same time I listen Radio Fm on my phone.
There is a big noise and interference,I also try different lenght micro usb cable,and others diy power bank
but same story..
only with the Miller ml-102 radio FM works fine.
Can be the interference or paradisic current from the small inductance on photos 1 that do the problem?
Circuit of Miller ml-102 does not have inductance.

Edited by: Alen on 03/09/2016 - 10:22
will34
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The output probably is not “clean” enough and has high noise, this could also lead to your phone heating up while charging and losing efficiency.

It could also mean the circuity is sending the wrong voltages across the data lines (bad/wrong output coding). This can’t be changed.

HKJ
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All power banks have inductors (Inductance), that is required to boost the voltage from a LiIon cell to 5 volt, but not all power banks is designed to reduce RF noise enough.

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

Alen
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thanks for reply
yes but on the Miller inductance seem to he shield instead the others that you can see the copper.
Can do that Rf interference or is bad design cicuit problem?
This can damage the phone in future?
wich good tester for powerbank can measure dangerous current peak or paradisic?
thanks.

HKJ
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Alen wrote:
thanks for reply yes but on the Miller inductance seem to he shield instead the others that you can see the copper. Can do that Rf interference or is bad design cicuit problem? This can damage the phone in future? wich good tester for powerbank can measure dangerous current peak or paradisic? thanks.

There are legal limits for RF radiation, but to measure them you need a shielded room, spectrum analyzer and a calibrated antenna.
Usual it is cable born noise that will interfere with the phone, this depends on the circuit board layout and also on the parts used.
Again a spectrum analyzer and a fancy setup is the best tool, but a oscilloscope can help and will show any voltage peaks (This is what I uses in my reviews).

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

Alen
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Thank you
So you consider better to avoid these diy bank for charge the phones or you know a good diy power bank without this problem?
I just have digital tester so can’t measure with professional instruments.

Werner
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I guess there are two possible problems.
1. The 5V have a lot of ripple which disturb the radio.
2. The powerbank is some sort of fm jammer.

Maybe you should make some tests to find out what the problem is.
Does the phone radio work when you power another device with the power bank and hold it next to the radio Phone?

What is your phone using as an Antenna? The headphonecable?

HKJ
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Alen wrote:
So you consider better to avoid these diy bank for charge the phones or you know a good diy power bank without this problem?

I will not recommend or reject any power bank or DIY circuit without testing, but as you can see I have not tested that many power banks.

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

Alen
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Do you take in consideration to test them with your instruments?
there are many diy bank on ebay for less 2/3 usd
they be interest for who search a budget diy bank that can insert prefered battery,and to avoid this noise problems
thank you again

hank
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Simple test — walk outside away from other electronic devices with a handheld AM radio.
Tune through the dial to ‘quiet’ ranges in between stations
Move the power bank (while it’s operating something ) around and see if it’s emitting radio noise, and how far away it’s annoying.

There’s an awful lot of radio noise (“electronic smog” is another name)

SawMaster
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Dash-cam users encounter a lot of this kind of problems since most of our cam’s run through a 5VDC cigarette-plug converter. Sometimes a high quality shielded cable will help, sometimes shielding the PS (wrap with aluminum foil connecting to ground somewhere) helps, sometimes a different PS helps but as often as not you’re only help is increasing the distance between PS and cables and all parts of the radio including antennas and their cables. Sometimes there is no cure.

Almost all electronic circuits generate RFI- the only question is how much and is it a problem. The FCC rules regarding allowed radiation levels are almost never enforced and I doubt that they are even tested for, but the best circuit designers will use shielding to mitigate as much of this as they can- which is why interference is more prevalent on cheap stuff where costs are cut to the bone. It can wreak havoc on AM, FM, and/or digital satellite receivers. Otherwise it is generally not harmful.

Your devices plugged into a PS are almost certainly going to be OK- there’s enough design tolerance to cope with less than perfect outputs. And cell phones, wifi devices, Bluetooth, etc are all designed to not be affected by the RFI as they have to be in order to function when charging. But your average radio receiver isn’t going to like them!

Phil

HKJ
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Alen wrote:
Do you take in consideration to test them with your instruments? there are many diy bank on ebay for less 2/3 usd they be interest for who search a budget diy bank that can insert prefered battery,and to avoid this noise problems thank you again

My main problem is time. I publish more than 4 reviews each week and do not have time to do more and with all the usb stuff I already have in queue I will not get around to the cheap DIY power banks the next couple of months.

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

Alen
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Thanks all for replies
Yes I have
try before some combination
And result is that Sony shorted cable(shield)noise is high.
Only with a cheap 2 meters cable(not shield)noise FM is very low.
that caused by cable attenuation??
And this not affect the antenna earplug(I have put powerbank with the 2 meter cabled near the phone and noise remain low.

SawMaster
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The cable which works best may not be phase-resonant on the interference frequency.

Given the right length, a wire acting as an antenna may actually not radiate because the top of one phase reflects from the end, and in returning backwards meets with the top of the next phase coming along in sync and thus cancels both phases out continuously. But it could be a number of things so all you can do is try different ideas till the problem is minimized or solved.

Phil

snakebite
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i dont see much in the way of output filtering on that thing.at the price point those sell for what do you expect?
my guess is the output contains a lot of ripple,noise,and switcher spikes.it will look awful on a scope.