There’s a chance that this could work for other USB devices (maybe an iPhone too, but I don’t have one), but there’s also a chance that this could fry your device, car, or perhaps eat all of the cheese in the house. If you’re not confident, or not competent, you probably don’t want to try this. I accept no responsibility for any bad things happening.

Step1 Bits need

You shouldn’t need more than the fairly standard soldering tools, a multimeter, and a couple of resistors (not shown) — I grabbed a couple of SMT resistors from an old CDROM drive.

 If you want the very simple steps without any instructions, all I did was connect a 27k Ohm resistor from V+ (Pin 1) to D- (Pin 2), then another 12k Ohm between D- and D+ (Pin 3). Dead easy.

Step2 Open the charger

You need to disassemble the charger (actually you could probably do this in a USB extension cable, but I didn’t want any more clutter).

Take the fuse and cap out. Then you need to split the charger open. Mine was welded together so I had to saw through both sides of the case and then lever it open. Don’t cut too deep with the saw or you’ll end up going through the components of the charging circuit.

Step3 Add the resistors

You need to add two resistors. You should do a continuity test first to determine if your two central pins are connected to any others. If they are, you’ve likely got a different charger and this probably won’t work.

According to the USB charging and power spec I should be able to simply short the two central pins (the data lines) and the device will detect that it’s connected to a charging device and start charging.

I tried this first of all, but it didn’t work (the iPod detected it had been plugged in to something, but refused to charge). I knew the iPod charged from my MintyBoost!, and after a quick look at the schematic and some playing with the multimeter, I decided it would be worthwhile adding a couple of pull-up resistors.

I don’t think the values are that vital (the USB spec is quite forgiving), but I decided to try matching roughly what the MintyBoost! was giving, apart from the V+ to D- resistor, which was guesswork.

Don’t forget to check that you’ve got the correct resistance between the pins, and that they’re not connected to anything they shouldn’t be!

Step4 Test and rejoice

After reassembly I tested the charger with a device I didn’t care about — in this case a broken DG-100 GPS datalogger — to check nothing (useful) exploded.

Next I tried all three iPods I could get my hands on. Success!

I wrapped the charger with duct tape to complete that “finished” look.

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Currently, the electronics require a large amount of energy to operate. And to meet this voracious consumption, nothing is more practical than dry batteries and batteries charger. When the energy ends, you simply take your rechargeable dry battery and put it in the charger and that’s it: it is ready to be used again. In addition, rechargeable dry batteries last more than common dry batteries -from 2 to 4 times. And they have been developed to be used in equipments such as digital cameras, some GPSs etc..

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And the industry of battery manufacturer has bright prospects for the future. It is reported that India’s leading dry cell battery manufacturer Eveready Industries is eyeing a growth of 10 percent in 2009-10.

Referred to dry cell batteries, they are common things in our daily lives. I would like to remind everyone to pay attention to the classification of used batteries. I think we’d better choose to use rechargeable batteries. It is economical and environmentally friendly.

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What are the kinds of charger?

There are various types and capabilities in the market. The charger is connected to the type of batteries for which it was designed. Most of the dry batteries are rechargeable NiMH (nickel-metal hydride). Until recently, it was also common in NiCd batteries (nickel-cadmium). The NiMH offers a much larger capacity, and it can be found in both small size (AA) and (AAA).

How do I choose a charger?

The correct choice of the charger is very important to the health of rechargeable batteries. It must be compatible with the carrying capacity of the battery. Give preference to the acquisition of the charger / battery together, as a charger with different time load cell can damage it.