Build An Emergency Charger For the 505 Reader

[BBRags]

A caveat: I am not responsible if your reader burns out after plugging in this recharger. The charger works fine for me. I built it when my 505 froze and would not recharge from the USB port. There is no product like this on the market (that I am aware of), so do-it-yourself is the only way to get one.

This emergency charger is based on Energizer's Energi-To-Go (ETG) cellphone charger. It runs on 2 AA Lithium batteries, is small and lightweight and will fully charge a 505 reader and just about any other reader that uses a 5VDC adapter. One set of AA Lithium batteries should fully recharge a 505 reader several times. The mod is simple, but will require some electronics skills. In short: take one of the ETG cables, cut off the cell phone plug and replace it with a Sony reader plug (or Sony PSP plug - same thing). That's it.

My Sony reader/PSP plug came from an old universal battery (seen as a big black disk in the pictures) that I don't use anymore. The battery cord had a receptable that accepted a set of interchangeable plugs. Any electrical cord with a Sony reader/PSP plug on it can be scavaged for this project.

Parts:

1 Energi-To-Go charger pod
1 Energi-To-Go charger cable (for any model cell phone)
1 cable terminated with a PSP power plug

misc: soldering iron, solder, ohmmeter or continuity tester

The ETG chargers may or may not be discontinued products. I see them being sold online and in stores heavily discounted. The original retail price was $30. I purchased two ETGs for Motorola phones from an Office Depot store for $1 each on closeout. Office Depot's website is still selling them for about $14. Buy.com's marketplace has some for $2 (but the seller is charging almost $8 for shipping). At one time, Target had these on closeout for about $5.

As far as I can tell, the charger pods are the same for all cell phone models they support. Only the cables are different. They output 5-6VDC, which will initiate the charge cycle in the 505 reader. If you're not sure, measure the voltage output of the ETG with a voltmeter. It should fluctuate between 5 and 6 volts. While the reader draws power from the ETG pod, a blue light on the pod flashes. When charging is finished, the blue light turns off.

Instructions:

1. Each ETG cable has a plug on one end that fits into the ETC and a plug on the end for the cell phone. Cut off the cell phone plug, leaving as much cable attached to the ETC plug as possible.

2. Using a craft knife, cut off about 3/8 inch of the outer rubber jacket to expose two wires: red and black. The red wire is connected to the tip of the ETG plug and carries positive voltage. The black wire is connected to the body of the ETG plug and carries negative voltage.

3. Strip off about 1/8 inch of the insulation from the red and black wires to expose the copper.

4. Trim the PSP cable to about 4 or 5 inches (or whatever length desired).

5. Expose the copper of the positive and negative voltage wires in the PSP cable. An ohmmeter or continuity tester can tell which wire is positive and negative. The PSP plug is a barrel-type connector. The positive wire will be connected to the metal tube inside the barrel. The negative is connected to the metal tube on the outside of the barrel.

6. Solder the positive wires of the ETG and PSP cables together.

7. Solder the negative wires of the ETG and PSP cables together.

8. Insulate the connections so they don't touch and short out. I used heat-shrink tubing. Electrical tape will do. Although it tends to unravel, it can be secured with regular sticky tape.

[Nvidiot]

Dealextreme has those for sale in 2 parts as well, if you don't want to solder: 2xAA battery holder with USB plug output and an USB -> PSP powerplug conversion cord. That's what I use for emergency charging my 700, and the USB -> PSP powerplug conversion cord comes in handy to be able to charge the reader while reading via a PC with an USB port too

[BBRags]

Nvidiot, DealExtreme has SOOOO many adapters and are SOOOO cheap! Which one is the product you use and how much was it?

The Energizer ETG retailed for nearly $30 when it first went on sale. For this humongously higher price, I can only hope the ETG had (at least) a higher quality finish. Maybe the exorbitant price is why the product failed and is now on closeout.

When I first researched doing an emergency charger, I thought of trying to put 4AA cells together to get 6V, but the lack of an internal regulator feeding these sensitive electronics really bothered me. If I had built my own voltage regulator, it would have cost me lots more than the $15 I paid for my first ETG. I'm still happy to have it though. It saved me from junking a 505 reader that was frozen and no longer recharging from the USB port.

If anyone wants to build my project, if you can find an ETG for $1 and can do simple soldering, it is totally worth it. Buy one to recharge your cell phone and convert one of the extra adapters (they usually come with 2 or 3 adapters) to recharge the reader.

[Red Alert]

How is it possible that two AA batteries which in series have a voltage of approximately 3VDC are able to fully charge a battery that operates at 5.2VDC?

To me, it would seem that at best you would get only a partial charge.

Can you clear up this point? TIA!

Ralph

[BBRags]

How is it possible that two AA batteries which in series have a voltage of approximately 3VDC are able to fully charge a battery that operates at 5.2VDC?
...
Can you clear up this point? TIA!

Yes I can. The ETG has an internal voltage doubler circuit (possibly even a tripler, contingent upon the method they use to regulate the voltage). A doubler is not free. If the voltage output goes up, the current output will go down, but that doesn't matter if the cellphone or reader can still recharge. (It does matter in some situations if you want both higher voltage and high current.)

That's the advantage of the ETG: it needs only 2 AA batteries and it's smaller, lighter, easier to carry. You will see on the web some simple rechargers that use 4AA batteries, which will give you 6V in theory. Sometimes you get more than 6V because batteries aren't precision.

You have to be careful though. If the cellphone or reader expects to see 5V and you plug in 7 or 8V, it may or may not damage the device. That's why a regulator is needed: it forces the output to stay at 5V.

Now, back to the basic 4AA recharger. That may work with some devices, but as soon as the voltage falls below 5V, it will stop recharging.

It was due to all these considerations that I shopped for an emergency charger that was lightweight and regulated. If you measure the output of the ETG with a voltmeter, you will read a voltage that seems to vary between 4 and 6V in cycles. I think that's because it has a smart detection circuit that tries to figure out what voltage the device needs to recharge. For example, early Nokia phones needed 5V to recharge, but later ones need 5.2V. That 0.2V difference is important. Without 5.2V, Nokia won't recharge.

That's a lot of features to cram into a small recharger and maybe that's why they priced it so high to start. At those closeout prices, the ETGs are bargains, if you have some soldering skills.

[Nvidiot]

http://www.dealextreme.com/details.dx/sku.5503 that's the adapter lead I use
http://www.dealextreme.com/details.dx/sku.26465 that's the 2xAA -> USB power I use.

Note: with 2xAA in it (rechargables) it does not fully charge the PRS700 I have, but it does get it up from dead to 3/4 full, which is plenty for me

It DOES come from DX, so that means the quality isn't awesome, but for those prices I'll risk buying a lemon every now and then. So far these two items are holding up well.

[BBRags]

Nvidiot, those are very good deals. Can you use the emergency charger to plug in to the reader's USB port too?

with 2xAA in it (rechargables) it does not fully charge the PRS700 I have

Does the PRS700 also recharge with 5Vdc?
Have you tried alkaline batteries instead of rechargeable batteries?

[Nvidiot]

Originally Posted by BBRags

Nvidiot, those are very good deals. Can you use the emergency charger to plug in to the reader's USB port too?

No, as the emergency charger does not identify itself as a PC and thus it will not charge the reader. However, with the conversion lead to PSP power plug it works fine.

Does the PRS700 also recharge with 5Vdc?

Yes, just like the 300, 600 and 900.

Have you tried alkaline batteries instead of rechargeable batteries?

No I haven't, I never use alkaline batteries, only rechargables (I have several 2500 mAh AA rechargables)

[gczobel]

This work with my old Sony Reader 500?

[BBRags]

gczobel, yes it will work IF the 500 recharges with a 5V adapter.