# New unique way to charge your smartphone [Image]

For those that are wondering, that is the battery of a Samsung smartphone being charged without a USB/outlet wire. Why? I have no idea.

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• New Moon

I work in the consumer electronics industry. I normally use this type of charging method to charge my colleagues’ phone batteries every now and then when they forgot to charge it up at home. I even made a backspoke usb clips for it. Most phone batteries can be partially charged in no time. I can confirm that it works at all time and it is only safe if you have prior knowledge of the battery’s charging rate, voltage and + – terminals.

1C = battery’s normal charging/discharging rate. If the battery is 2000mAh, you should charge it at 2000mA max current. If you charge it at a lower amp, say 500mA as in this photo, you get better charge retention. If you don’t have time, just throw in 1A or 2A, no problem, your battery can take it. It might warm up a bit tho.

The proper way to charge a Li-ion battery involves 3 steps: 1. CC charge, 2. CV charge, 3. Trickle charge (topping charge). In the above photo, the battery is absorbing 480mA while being charged with CV step, this is absolutely wrong! It damages the battery.

The battery should be charged at a constant current rate while the battery voltage climbs up nearly to the specified voltage, say 4.0V for a 4.2V battery. Imagine an empty bucket. It doesn’t matter how much water you throw into it, at reasonable rates of course, it will hold it easily. That’s why we say 1C, 2C etc., not 100C!

After that, it should be charged with the constant voltage step, so that the battery can decide how much current it wants to absorb according to its changing/dynamic internal resistance, rather than force feeding it with a constant current. Imagine, now your empty bucket is nearly full, so you may want to readjust your initial (careless) filling rate, otherwise it will spill over and create a mess. Well, in the battery’s case, the spill over = overheating, gassing and/or explosion!

Trickle charge step is only necessary if it stays in the charger or storage for a long time. The battery looses charge at a very slow rate just by being in the storage! Imagine your fully filled water bucket, leave it for a week, come back and check it out. You will find that some water has evaporated!

I hope it explained, sort of!

• stephan

the simplest answer: because you can.