For those who own any powerbank and oscilloscope, can you please share the noises or ripples of your powerbank? I want to see the noises of the 3.7V lithium ion (inside all powerbank) as it is buck boost converted to 5V. Some may have more noises and some little?

Also I'm looking for the purest 5V battery source that doesn't use powerbank 3.7V lithium ion. Where do you find them? pls also share oscilloscope output of it if you have to show pure 5V DC signal without any noises or ripples.

 

Hi Secan.
Use two 3.7V Li-on batteries in series, so 7.4V driving a 5V linear LDO regulator., noise free.

E

 

I want to see the noises of the 3.7V lithium ion (inside all powerbank) as it is buck boost converted to 5V. Some may have more noises and some little?

All powerbanks use boost converters because they need to be charged by USB voltage. Why do you care about the noise? Anything powered from a powerbank can tolerate tenths of a volt of noise; assuming output voltage is 5V.

I'm looking for the purest 5V battery source that doesn't use powerbank 3.7V lithium ion. Where do you find them?

Since there's no battery chemistry that yields exactly 5V, you're out of luck.

 

All powerbanks use boost converters because they need to be charged by USB voltage. Why do you care about the noise? Anything powered from a powerbank can tolerate tenths of a volt of noise; assuming output voltage is 5V.
Since there's no battery chemistry that yields exactly 5V, you're out of luck.

I'm doing microvolt FFT analysis and the boost converters noise are creating many frequency disturbances. The device is powered by 5V input. AC adaptor can create many 60Hz and harmonics noise. So my choice seems to be only powerbank but noises affecting it.

 

So my choice seems to be only powerbank but noises affecting it.

So you're trying to use a powerbank for a non-standard application, i.e. one that it wasn't designed for. You should use a battery with a linear regulator.

 

Batteries are not noise-free. The path taken through the electrolyte by the electrons is constantly changing. That produces noise.

 

Hi,
I was referring to noise from the Boost circuit, which he was asking about, NOT any other noise source
No one said batteries are noise free, but they don't have switching spikes.
E

 

Hi,
I was referring to noise from the Boost circuit, which he was asking about, NOT any other noise source
No one said batteries are noise free, but they don't have switching spikes.
E

the TS seemed to think so as he was "looking for the purest 5V battery source"

 

I do not have the time or the inclination in getting embroiled in a pointless discussion.

If my suggestion to the TS, gives him a result that is acceptable to his requirement of a 'purest 5V battery source' that is sufficient for me.

 

Four rechargeable NiMh cells in series would probably do as a nominal 5V supply. For most of the discharge curve the voltage should be in the 5.2V to 4.8V range.

 

hi alec,
This is what the TS posted in another thread on the same topic.
The specification is medical, which concerns me.

E

 

I'd be surprised if the bio-amp shown in that other thread needed anything like 6A for which that adapter is rated; but we haven't been told the amp's current rating.
The earth symbol on that adapter presumably implies that a grounding connection is provided, but the TS has said that there is no mains supply grounding provision in their country.
I would hope that the 'For medical use' marking also means that there is proper mains isolation within the adapter.

 

Hello,

It states the IEC60601 on the supply:
https://en.m.wikipedia.org/wiki/IEC_60601

Bertus

 

It states the IEC60601 on the supply:

Yes, but it's not unknown for dishonest or misleading labelling to be used on some products. Hopefully this particular supply has honest labelling.