# Keeping electronics charged when the grid is down



## sideKahr (Oct 15, 2014)

I have a solar powered 12 volt battery backup system, but no easy way to charge flashlight batteries and other 5 volt devices without running the energy-hog inverter. I couldn't find a commercial DC to DC step down converter that I liked, so I built one.

















It will charge at 5.25 volts and 3 amps, on 2 USB connectors. Just the ticket!


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## budgetprepp-n (Apr 7, 2013)

Dang,,That's nice


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## sideKahr (Oct 15, 2014)

Thanks. It wasn't a kit, I designed it myself.


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## Camel923 (Aug 13, 2014)

Awesome.


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## azrancher (Dec 14, 2014)

sideKahr said:


> Thanks. It wasn't a kit, I designed it myself.


OK, so where is the circuit diagram....

*Rancher*


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## Kauboy (May 12, 2014)

Me likey.
It's aesthetically pleasing too.
What is the box covered with/made from?


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## A Watchman (Sep 14, 2015)

Very well done sideKahr! :vs_clap:


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## Back Pack Hack (Sep 15, 2016)

One can purchase similar devices that will charge batteries directly, not supply a certain voltage for a specific charger.


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## dwight55 (Nov 9, 2012)

Inverter may be a hog, . . . but with a solar panel charging the battery, . . . it's all free anyway, . . . 

That's my route.

May God bless,
Dwight


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## sideKahr (Oct 15, 2014)

azrancher said:


> OK, so where is the circuit diagram....
> 
> *Rancher*


I didn't have a detailed one. Just some calculations for LEDs, amperage summary for fusing, and resistor heat dissipation. I did most of it on the fly, but I did have a few "do-overs".


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## sideKahr (Oct 15, 2014)

Kauboy said:


> Me likey.
> It's aesthetically pleasing too.
> What is the box covered with/made from?


It's a cheap plastic box sprayed with metallic looking paint.


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## Redneck (Oct 6, 2016)

I ain't smart enough to build anything like that but am smart enough to buy a Humless solar generator, which has USB connectors also.


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## SGT E (Feb 25, 2015)

Just put in 600 watts of solar panels in a homebrew rack...after the run from panels to house through #2 wire I got it set up and running through Renology controllers at about 16 amps and 15 volts on each side in max sunlight. Each side charges 2 each 6 volt deep cycle golf cart batteries in series...I can switch a full 32 amps to either set of batteries....That's a lot of satellite tv..house lights and notebook computer use per day! Looking at 2 400 watt windmills now and another 600 watts of solar panels.


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## morganrogue (Dec 13, 2017)

Great idea! I think my husband could make this. Going to show it to him. 


Sent from my iPhone using Tapatalk


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## Smitty901 (Nov 16, 2012)

Also have a solar panel it charges a battery that can power an inverter or directly charge in dc or USB. Will charge most any device. Given enough time it will charge battery powered tools . I want to expand it.


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## azrancher (Dec 14, 2014)

Back Pack Hack said:


> One can purchase similar devices that will charge batteries directly, not supply a certain voltage for a specific charger.


I bought one of those, about $20... junk

*Rancher*


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## Back Pack Hack (Sep 15, 2016)

azrancher said:


> I bought one of those, about $20... junk
> 
> *Rancher*


You didn't spend enough to buy the right one, then.


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## azrancher (Dec 14, 2014)

Back Pack Hack said:


> You didn't spend enough to buy the right one, then.


Perhaps not, it was a combined solar cell array, not very big, and with just USB and a 12VDC jack.

*Rancher*


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## Back Pack Hack (Sep 15, 2016)

azrancher said:


> Perhaps not, it was a combined solar cell array, not very big, and with just USB and a 12VDC jack.
> 
> *Rancher*


Try an XTAR Dragon VP4 Plus.


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## Piratesailor (Nov 9, 2012)

Smitty901 said:


> Also have a solar panel it charges a battery that can power an inverter or directly charge in dc or USB. Will charge most any device. Given enough time it will charge battery powered tools . I want to expand it.


I pretty much have the same set up. 200w solar panel to charge either a 12v or two 6v batteries, inverter and also a cig lighter attachment. All this for charging everything from small batteries to a laptop. Tested it in the past and it works fine.


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## paraquack (Mar 1, 2013)

As a Christmas favor to everyone, would you please open your masterpiece and draw out a 
schematic and a parts list for those of us talented enough to be able to put things together 
but not smart enough to figure out the reasons. Pretty Please????


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## sideKahr (Oct 15, 2014)

paraquack said:


> As a Christmas favor to everyone, would you please open your masterpiece and draw out a schematic and a parts list for those of us talented enough to be able to put things together but not smart enough to figure out the reasons. Pretty Please????


I'd be too embarrassed. It's a rats' nest of kludges, snapped off perf boards, wire jumpers, solder blobs, and strings of hot glue. I'll try to reverse engineer a circuit diagram, but I'm not promising anything.


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## paraquack (Mar 1, 2013)

I know a lot of us would appreciate it. Thanks in advance!


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## sideKahr (Oct 15, 2014)

@paraquack "The things I do for England."

This, to the best of my ability, is how I did it (I think, don't quote me, Your Mileage May Vary, build at your own risk, lead solder is known to the State of California to be a carcinogen)









I forgot to note the internal fuse, I used a 3 amp.
Also forgot the blue LED resistor is a 150 ohm.


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## paraquack (Mar 1, 2013)

Thank you for taking the time to draw out.


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## A Watchman (Sep 14, 2015)

sideKahr said:


> @paraquack "The things I do for England."
> 
> This, to the best of my ability, is how I did it (I think, don't quote me, Your Mileage May Vary, build at your own risk, lead solder is known to the State of California to be a carcinogen)
> 
> ...


Thanks sideKahr, your schematic makes sense. Well Done!! :vs_clap:


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## Kauboy (May 12, 2014)

sideKahr said:


> It's a cheap plastic box sprayed with metallic looking paint.


Ah, then the pictures (or my eyes) are deceiving me. It looked like "flecking" fuzz or short pile carpet type material to me, like floor carpet in a car.


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## A Watchman (Sep 14, 2015)

Kauboy said:


> Ah, then the pictures (or my eyes) are deceiving me. It looked like "flecking" fuzz or short pile carpet type material to me, like floor carpet in a car.


That's what I thought as well.


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## sideKahr (Oct 15, 2014)

Yeah, it has a weird , 'soft' look in the right light.


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## bornprepper (Dec 27, 2017)

Damn! That looks sweet man!


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## Ayn Rand (Dec 31, 2017)

Beautiful design but I have a question. 
Couldn't you just buy one of those $4 things that you plug into a cigarette lighter (12v) that has a USB port in it? Then just solider some wires to it and hook them to the battery? Wouldn't look as pretty or be as solid but it should work.


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## paraquack (Mar 1, 2013)

Sure, why not.


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## sideKahr (Oct 15, 2014)

Ayn Rand said:


> Beautiful design but I have a question.
> Couldn't you just buy one of those $4 things that you plug into a cigarette lighter (12v) that has a USB port in it? Then just solider some wires to it and hook them to the battery? Wouldn't look as pretty or be as solid but it should work.


Yep, you can do that. And I have of few of those, they're limited to about 1 amp, and even the good quality ones get too hot for my taste. I wanted something that would run multiple 18650 and nickel metal hydride battery chargers and operate 5 volt lighting and soldering irons dependably.


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## Back Pack Hack (Sep 15, 2016)

sideKahr said:


> ............ and soldering irons dependably.


Just use an ordinary soldering pen and a fire.


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## sideKahr (Oct 15, 2014)

Back Pack Hack said:


> Just use an ordinary soldering pen and a fire.


Does that actually work? Doesn't the tip get too dirty to be useful for electronics work?


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## Back Pack Hack (Sep 15, 2016)

sideKahr said:


> Does that actually work? Doesn't the tip get too dirty to be useful for electronics work?


Soldered for years using fire. But then again, that was back before über-fine electronics prevalent today. I was soldering circuit boards before chips came along.


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