Combining StefanV USB Charger & 3V-5V Step-Up Converter for Windbelt Power Bank?

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#1 21666118 25 Jan 2013 12:24

Ruuth F Ruuth F

Anonymous

Post #1
21666118 25 Jan 2013 12:24

http://www.stefanv.com/electronics/usb_charger_photos/schematic.gif
http://www.eleccircuit.com/wp-content/uploads...ep-up-converter-with-undervoltage-lockout.jpg

Hello,
I'm thinking of making a power bank for my windbelt generator with 5V output. So, can I combine these 2 circuits at their battery terminals? or how else can I combine them? I googled for power bank circuit but none of them that I found is suitable for my project. Help?
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#2 21666119 25 Jan 2013 12:32

Mark Harrington Mark Harrington

Anonymous

Post #2
21666119 25 Jan 2013 12:32

Hi Ruuth

I having difficulty understanding what you mean by combine What circuit and what circuit to what from what ?
Could you possibly draw a block diagram explaining or outlining what it is that you want to do and possible connections as you might percieve these to be

Cheers

Mark
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#3 21666120 25 Jan 2013 13:04

Steve Lawson Steve Lawson

Anonymous

Post #3
21666120 25 Jan 2013 13:04

So, is the idea to charge a bank of batteries from one windbelt generator? And by "power bank" do you mean the ability to draw power from a set of the batteries?

Which has a 5 volt output, your windbelt generator or the power bank? I'm assuming the wildbelt generator has a 3 volt output and you want to boost that to 5 volts -- why? To charge batteries?

Like Mark said, a block diagram would be nice.
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#4 21666121 25 Jan 2013 13:20

Ruuth F Ruuth F

Anonymous

Post #4
21666121 25 Jan 2013 13:20

Yes, that is the main idea, and yes by 'power bank' I mean the ability to draw power from the batteries.

Here's a block diagram of what I am trying to do. Sorry for not making it clear and thank you so much for replying.
#5 21666122 25 Jan 2013 13:24

Ruuth F Ruuth F

Anonymous

Post #5
21666122 25 Jan 2013 13:24

Sorry if I confused you! Here is a block diagram of how I want the circuit to work. Thank you for replying.
#6 21666123 25 Jan 2013 13:40

Mark Harrington Mark Harrington

Anonymous

Post #6
21666123 25 Jan 2013 13:40

Yes looks ok to me Ruuth only one way to find out build it !! Your final test if you like is always in the proof

Only one question I do have why drop to two 1.5 batteries (total 3 volts )when you might as well charge to 5 volts Seems as though your setpping down and stepping back up I cant understand your reasoning in this

Why are you doing it this way Nothing wrong with what your doing but it seems to be a waste of components if you can get away with less
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#7 21666124 25 Jan 2013 13:59

Steve Lawson Steve Lawson

Anonymous

Post #7
21666124 25 Jan 2013 13:59

I would use one charging circuit for each _battery_ (each group of series cells), and then use rectifiers to isolate each battery pack. So, lets say you have 3 batteries (made up of 2 cells each): you would have one 3v to 5v DC-to-DC converter feeding three separate battery charging circuits, each charging it's own battery, then three rectifiers. The anodes of each rectifier will connect to it's own battery and all of the cathodes would be connected together, which would be your _power bank_ "positive" terminal. If diode drop is an issue, then use Schottky diodes or fast recovery diodes.

You can also use one charging circuit to charge all of the batteries in a bank (assuming the circuit is designed to supply enough charging current), but if any of the batteries degrade before the others, then it will unbalance the system (i.e. the whole system will be vulnerable to one failure) -- so, it's a trade-off decision.

Also, the windbelt generator needs to be able to supply enough current to drive the charging circuit(s). And, not sure how the charging circuit will behave during low wind conditions (i.e. with inadequate voltage at the input). Might be wise to have a separate supply driving the "logic" circuitry and feed the output of the generator exclusively to the PNP transistor(s).
#8 21666125 29 Jan 2013 14:32

Frank Bushnell Frank Bushnell

Anonymous

Post #8
21666125 29 Jan 2013 14:32

Just to check, is your generator complete with voltage regulation circuit, or just a basic generator ?
Have you tested the available voltage and current output in various wind conditions ?

I would expect a basic wind generator to have an output of up to around 12 Volts, depending on wind speed.

Here is a very basic circuit that might do what you require.

It assumes a small generator, output of up to 1 Amp, perhaps giving up to 12 Volts in a good wind.
The battery is 7.5 Volts because basic voltage regulators drop a couple of Volts.
The 7808 should have a heat sink because it will get a little hot with good wind.

Bear in mind that wind generation in some areas is never as good as hoped for, due to lack of wind speed.
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Topic summary

The discussion centers on integrating StefanV's USB charger circuit with a 3V-to-5V step-up converter to create a 5V power bank powered by a windbelt generator. The main challenge is how to combine these two circuits effectively at their battery terminals to charge and draw power from a battery bank. Clarifications reveal the windbelt generator outputs approximately 3V, which requires stepping up to 5V for charging batteries and powering USB devices. Suggestions include using separate charging circuits for each battery pack with diode isolation (preferably Schottky or fast recovery diodes) to prevent backflow and maintain battery health. It is also noted that charging multiple batteries in parallel with a single circuit risks imbalance if one battery degrades. Questions arise about the rationale for stepping down to 3V batteries only to step back up to 5V, suggesting a more direct charging approach might be more efficient. Additional advice includes verifying the windbelt generator's voltage and current output under varying wind conditions and considering voltage regulation components like the 7808 regulator with heat sinking for stable output. The overall recommendation is to prototype the combined circuit and test its performance, keeping in mind the trade-offs between complexity, efficiency, and battery management.
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Combining StefanV USB Charger & 3V-5V Step-Up Converter for Windbelt Power Bank?

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Topic summary