Hello everyone,

I have a raspberry 4b and I want to protect it from 18650 battery pack because i'm so afraid of damaging it with overcurrents or short current.

I'm not advanced in electronics although I drew a noob circuit (assuming that we are using two 18650 3.7v batteries as below)

1- I placed 3 LM1117 (5v voltage regulators) in series to get an output of 3A (each one has 5v - 1A output and 15v max input ) to supply the raspberry
2- Capacitors to stabilize current but I'm not sure about the value
3- Resistors to protect from overcurrent, not sure about the values too
4- And 1A diodes to prevent reverse current

 

Welcome to AAC!

How do you plan to connect the regulator output to the 4B?

The diodes you show will prevent the Pi from receiving power. Why do you think you need 3 voltage regulators in parallel? Why don't you just put an external pass transistor on one?

Why would you ever want to have 3 batteries in series?

 

Hello everyone,

I have a raspberry 4b and I want to protect it from 18650 battery pack because i'm so afraid of damaging it with overcurrents or short current.

I'm not advanced in electronics although I drew a noob circuit (assuming that we are using two 18650 3.7v batteries as below)
View attachment 269131
1- I placed 3 LM1117 (5v voltage regulators) in series to get an output of 3A (each one has 5v - 1A output and 15v max input ) to supply the raspberry
2- Capacitors to stabilize current but I'm not sure about the value
3- Resistors to protect from overcurrent, not sure about the values too
4- And 1A diodes to prevent reverse current

Why not just buy a USB chargeable power brick?
Your diodes are backwards and I don't know which transistor pins you are using. What is the role of the resistors?

 

Why would you ever want to have 3 batteries in series?

Unless there is a step-up regulator, a 4.2v supply isn't enough to supply a Pi. It needs 5v.

 

Let 'em find out the hard way. There is a cost to solving non-problems in a redundant way.

 

I'd use a 3S (12.6V) battery with a 5V car adapter, since I can buy those at dollar stores. I suspect that's more efficient than stepping up 4.2V to 5V in a power bank.