Not because you need one… but just for the joy of building it yourself.


Imagine soldering the components, learning how power flows, and watching your own creation charge your phone.

Mods note: No self-promotion.

 

Welcome to AAC!

Imagine soldering the components, learning how power flows, and watching your own creation charge your phone.

I don't think it'd be worth the bother or the expense. Most people already have more phone chargers than they know what to do with.

 

I used to make 12V to USB chargers back in the day when that was a new thing. They sit idle now because higher current, modern solutions (USB-C, for example) are nearly free. It’s not worth it to DIY.

My kids were always amazed that the TSA never blinked when their DIY charger-in-an-Altoid-tin went through security.

 

A beginner product charging a kilobuck phone?? What could possibly go wrong??

 

Do not do this.

Note that *none* of the application circuits in the datasheet are battery chargers. This is because charging a lithium battery is dangerous. IIRC, a problem with a camcorder battery charger cost Sony BBBBBillions.

Even if you used a control chip designed specifically for a lithium battery charger, and Linear Tech has a bunch of them, it still would be a dangerous thing to try.

Learning about power flow is a great idea, but not with lithium.

ak

 

Battery chargers are very easy to build and Li-ion batteries are the easiest of all. So long as you limit the current per the battery requirements (Usually 1 to 2C) and have an accurate output voltage these batteries are well behaved. Typical cells are rated for 4.20V max and 4.25 abs max but newer cells can go up to 4.5V. If you stay at or below 50% charge you don't have to worry about capacity loss and NEVER allow discharge below 2V as this will kill the cell. My favorite charger to throw together is an LM317 as a current source followed by an LM317 as a voltage source: Automatic switch from constant current (First 80% of charge) to constant voltage (Last 20%). Lithium does not mind having a constant voltage at its terminals unlike NiCd and NiMH. You can buy batteries from Digikey and the like with protection circuits built in, making them nearly bullet proof. (Long history here... I designed the first on board Li-ion battery charger ever used by Qualcomm)

 

Besides the safety issue, messing with AC is no joke. You stand a good chance of messing up the phone and possibly hurting whoever is building this.thread has been locked pending moderator review.