Comments on: how-to make a ‘usb battery’

By: Réginald

Réginald — Sat, 17 Dec 2011 13:31:13 +0000

Why not use a 7805 instead of the Zener ???

7805′s are easy to find and they do not draw any significant current on idle… Keep the resistor as a current limiting device, but you shall be aware that a shunt Zener diode will draw a lots of current even when no device is plugged in the USB port.

By: Phyrehazurd

Phyrehazurd — Tue, 06 Dec 2011 01:21:18 +0000

The problem with using 4 AA is you would only get about about 20% of the charge from the AA batteries pushed into the device you are charging. At that point each battery would around 1.3 to 1.4 volts leaving you with 4.9 to 5.6 volts. Now your device is not charging, but is maintaining the current charge. You have to use the device with this USB battery plugged in to get all the energy from the 4 batteries.

I have not tried a 5.1 Diode, but using a 5 volt liner regulator and 5 AA batteries, the voltage dropped to low to charge the device after using only half the energy in the 5 AA Batteries(each battery was at 1.25 to 1.3 volts). You may be able to get away 5 AA batteries with the 5.1 Diode.

Also, it took three 9 volt batteries to get a full charge on my cell phone. 9 volt batteries suck when you pull a lot of amps from them.

By: Hariss Khan

Hariss Khan — Mon, 05 Sep 2011 12:47:05 +0000

how if we put a switch

By: coolmike8789

coolmike8789 — Wed, 27 Jul 2011 20:27:48 +0000

Couldn’t you do this with a 5v regulator?

By: Rioiek

Rioiek — Wed, 08 Jun 2011 09:42:54 +0000

I was thinking about 4 rechargeble AA or AAA:

4 times 1.2 = 4.8 volts. USB specs says: 4.5-5 volt is okay..

No other components needed imho..

I haven’t tried this myself, anyone wants to give it a go?

About the 12/9volts zener or 7805: if you are looking for a very efficient batterypack, consider the Recom R-78B5.0-1.5 .. it doesn’t “burn” the extra voltages but transforms them efficiently to 5 volts.. not cheap, approx $20..

By: MR. Jon

MR. Jon — Thu, 07 Apr 2011 00:12:22 +0000

this is retarded. it will create 5 volts but with the give resistance it will only supply something around 20 ma, most 5 volt chargers start around 500 ma. even with a 100 0hm resistor its still only about 50 ma. this is a inefficient toy, go get a 7805.

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By: merringer

merringer — Thu, 01 Apr 2010 04:47:11 +0000

i was gonna take a 5v psp battery and solder wires going directly from that to the usb to charge my ipod and i was just wondering if that would work properly… any answers?

By: mikey

mikey — Sun, 21 Mar 2010 14:42:12 +0000

I Made it the same way. but i can’t upload my iPhone.
Can anybody help me?

By: jonny

jonny — Thu, 28 Jan 2010 00:32:21 +0000

I MIGHT NOT HAVE GOT IT RIGHT I GOT 5.8V BUT NO CHARGE WHATS GOIN ON HERE?

By: jonny

jonny — Thu, 28 Jan 2010 00:31:16 +0000

I DID NOT GET THAT TO WORK IS THERE A DIAGRAM? IM GETING 5V

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By: Marc

Marc — Fri, 13 Jun 2008 19:43:53 +0000

I am finding solar panels on Ebay. That would bypass the need for a battery.

By: battman

battman — Fri, 11 Jan 2008 04:07:36 +0000

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