I want to power my Raspberry Pi 3 model B+ using a battery. It turned on and worked perfectly with:
1) a 5V 1A powerbank or adapters
2) and a 5.5V(4.2+1.3) battery connected directly.
However, i was not lucky in getting it to work with two lithium ion batteries in series 8.4V by either linear and switch regulator of 5V output. For linear regulator, i used 7805 and for switching regulator i used LM2596.
i have tried many variations of the 7805 linear regulator circuits and using different components and testing with multimeter but it did not work with raspberry pi. The same results with the LM2596. I tried both by powering using the USB micro port and the two 5V and GND pins The micro USB cable is perfectly fine as i tried it with powerbank and adapters which worked.
Everything in my project worked fine with these regulators, arduino, lights, motors, sensors except raspberry pi. I tried to make it work separately, i thought maybe the other components are intefering with it, but it still not working. Either power it directly using 5V batteries, or use powerbank or adapters. Its a dilemma because i tried everything i could think of.
Many people recommended this online and it worked for them. Could it be because of the new raspberry pi 3 B+ which has some changes. Please help, i will appreciate it very much.
In the commments, i was told that there could be not enough current being supplied by the regulators. That is true, not enough current is supplied. Thank you for letting me know. I tried the circuit below in an effort to solve my problem. Here i used a TIP142 transistor and a zener diode of 5.6V. I got a voltage of around 5.5V across the emitter capacitor. It worked! It powered the raspberry pi and got the remote desktop and shut it down.
However, i saw a white smoke, i thought im hallucinating, maybe a signal from my brain to take a smoke break, but the zener diode was getting hot. And to be honest the potentionmeter could be replaced with a tiny ohm resistor, cause i spinned it all the way to almost zero resistance. Thats how i got the maximum current. Please can you advice me on how to improve this circuit, so that the zener diode cannot get very hot. Or if you know a way to get high current, please do share. Thank you very much for your time.