Stun gun

Bi e n

Gracias

Add one diode and one capacitor at the output. you will have more voltage.

@heuler-but the diode reverse voltage and the capacitance will be lower and blow up the diode, so I did a voltage split on the diodes.

Mr. Voltransistor you are a pain to search for lol. I need your input on a circuit design, I want to charge a 3.7V Li-Ion from 5V USB with nothing but diodes/transistors/resistors, I'm currently paralleling the battery in my phone to another phone because my charging port broke, and I'm poor and can't afford another, so it's battery is tied to the positive and negative of another device that has a charging port so I can keep my phone alive for the time being, but I'd love to replace it and be able to design a separate cable for it that plugs into USB and safely charges the 3.7V battery. The battery has a control circuit on it with a max input of 4.2V and it's a 2.2Ah battery, any way you can help me out good old friend? ;)

@ETJAKEOC-Ill definetly help you out. You need to regulate it at 4.2V. For an hour, you need 2.2 Amps, with 4.2V it would be 1.9 ohms. If you charge it within 100mA, it would take 26.4 hours. I recommend you use more than 200mA, 5V power supply, and using a voltage regulator around 4.2V which regulates it around the same voltage when the voltage varies and mainly helps protect it from overcharge. If you have any questions, let me know. =-)

I have a USB charger that outputs 1.1A at 5VDC, I looked into one of your battery charging circuits and slimed it down a lot, I'll link a screenshot below (as it's a derivative and won't share) and lemme know how well you think that'd work, it doesn't have to be able to power the phone at a whole whopping 2.2A (which mine never uses, always in airplane mode, wifi is the only thing on, keep my screen dim) but as long as it can charge the battery up I'll be happy

Screenshot is at https://www.dropbox.com/s/ddpubgkl67dnkri/MXC.png?dl=0

Yeah, that would work.

Awesome :)