Simple Solar Power Bank Chargnig

[msuffidy]

It has been an idea of mine for a while to make a solar charger for phones etc. that take a really low solar input and slowly pulse an output. So what I think I could do is basically have a solar panel of some sort, a box with the solar panel on it or connected to it, and on the other side a usb host connector.

So what I think would work is to like output 5v on the host port for like 10 seconds to a usual charge bank every now and then when there is enough stored power to do so. So the steps I was thinking of was basically converting a lower than 5V output from solar panels to 5v bursts to a capacitor bank of some sort. Then there would be a threshold switch of some sort to output to the 5v port when the caps were full. Also you may have to do something to keep the output level at 5 volts. I am sure there are some schematics for typical ways to do this? In a way *1 and *2 may have similar circuitry as they are similar but with different durations.

[msuffidy]

I was just thinking also say you power bank is full that would mean the capacitors would not discharge or would take a long time to discharge, which would I guess saturate the solar panel? So if a solar panel is saturated, like I guess it would be if nothing was connected, it just stays that way and there is no damage to anything?

[Konkedout]

I don't get the point of this...

I have a setup with a 30W solar panel which produces about 18V, a Chinese made charge control module, and a 12V 7 amp-hour SLA battery.  The battery powers  two copies of my own device which generates slow 18V pulses which electrocute slugs when they happen to crawl across a pair of stainless steel wires laid across the top of the garden soil.

I think you can do similar but replace my slug-o-cuter with a 12V input USB charger host board of some sort.  Gosh I think most recent automobiles have this capability.  I have a couple of USB output adapters which plug into the 12V accessory outlet (cigarette lighter in very old cars) in my 2004 and 2007 vintage automobiles.

Pulsing the current out of the solar panel will not help you much.  You want to do proper DC-DC voltage conversion which is performed by the components I describe.

[msuffidy]

Well I think it generally helps to have a higher voltage out of the solar than what you in the end need, and then you need some sort of higher efficiency regulator. I was more looking at slowly charging something which needs some sort of step up inversion.

[Konkedout]

For what it is worth:

Voltage step up is generally done with a boost converter, while voltage step down is generally done with a buck converter.  Either can be efficient or inefficient according to the design details.  Buck converters are much more common and there are some that can offer 90% or 95% efficiency under some circumstances.  My slug-o-cuter includes a boost converter so I can hit the slugs with 18V.  So, yes the voltage starts at about 18 from the panel, gets bucked down (by the commercial charger module) to really about 13V for the SLA battery, and then gets boosted back up to 18V.   Given the desire to include the battery for overnight operation, trying to just keep everything at 18V would be more difficult.  The voltage change also facilitates battery charge control.

But none of the above requires fast or slow charging.   The solar panel and the boost or buck voltage conversion can provide higher power for faster charging or only lower power for slower charging according to its design.

Buck converters are more common because high voltage is better for sending high power over a distance, while the loads tend to operate from lower voltages.  That is why power utilities send out power at many thousands of volts rather than 120 or 240 VAC, although they mainly just use 50/60 Hz transformers to do the voltage conversion.

[msuffidy]

Or you can just buy one. I did a little research and it has been a very covered topic out there. I stumbled across a find.