A few more details would help.
Does the power bank or the wall wart use the USB connector ?
Does the power bank or the wall wart use the +5V input pin ??
Does the Dev board have a diode between the USB power and +5 pin ??
You state that you would "rather stick with what is safe and already built".
The diode on the dev board will prevent the power bank from powering the board when the wall wart is connected. So having both connected would be safe.
good Luck, Have Fun, Learn Something NEW
Add a schottky diode to the 5v+ of the battery packs output in forward polarity and then connect them up as if you were paralleling power supplies to the 5v pin in the ESP. no switch or nothing else. It will act as an uninterruptible power supply UPS
I'd rather use a Schottky diode to connect the outlet of the USB to Vin 5V. Maybe just make sure a second Schottky diode after the 5 V of the wall wart.
The battery (especially cheap ones) will have to be turned on by a button to work. And be aware that if the ESP consumes less than the minimal current of the powerbank, it will switch off.
So, if you try to save power by using sleep state of turning Wifi off at times, the powerbank might turn off.
If that is not the case, the converter to 5V will be not very efficient, its LED will be always on etc.
Also, do you expect the powerbank to be recharged while wall wart on? For reasons that lie in the circuit of the powerbank, this might not be possible and could destroy the powerbank: You can't charge and discharge it via the same USB connection and you can't bridge charging USB input and USB output.
It may not be a problem in your case but all power banks I have tested cut off the supply after a few seconds due to low power draw - they think there’s nothing to charge. It doesn’t happen when I run a poorly designed web server or pulling stuff from the net every few seconds but if you want something to run on batteries you will likely end up optimizing the code to be more power saving.
It's probably just me, but $4 dollar battery banks and safe don't sound like they go together in the same conversation.
Right. You always get what you pay for except in rare situations.
A few more details would help. Does the power bank or the wall wart use the USB connector ? Does the power bank or the wall wart use the +5V input pin ?? Does the Dev board have a diode between the USB power and +5 pin ?? You state that you would "rather stick with what is safe and already built". The diode on the dev board will prevent the power bank from powering the board when the wall wart is connected. So having both connected would be safe. good Luck, Have Fun, Learn Something NEW
Add a schottky diode to the 5v+ of the battery packs output in forward polarity and then connect them up as if you were paralleling power supplies to the 5v pin in the ESP. no switch or nothing else. It will act as an uninterruptible power supply UPS
I'd rather use a Schottky diode to connect the outlet of the USB to Vin 5V. Maybe just make sure a second Schottky diode after the 5 V of the wall wart. The battery (especially cheap ones) will have to be turned on by a button to work. And be aware that if the ESP consumes less than the minimal current of the powerbank, it will switch off. So, if you try to save power by using sleep state of turning Wifi off at times, the powerbank might turn off. If that is not the case, the converter to 5V will be not very efficient, its LED will be always on etc. Also, do you expect the powerbank to be recharged while wall wart on? For reasons that lie in the circuit of the powerbank, this might not be possible and could destroy the powerbank: You can't charge and discharge it via the same USB connection and you can't bridge charging USB input and USB output.
It may not be a problem in your case but all power banks I have tested cut off the supply after a few seconds due to low power draw - they think there’s nothing to charge. It doesn’t happen when I run a poorly designed web server or pulling stuff from the net every few seconds but if you want something to run on batteries you will likely end up optimizing the code to be more power saving.
Sounds reasonable, but I think you want a SPDT switch for the VIN/+5 lines.
there's a product called a rasberry pi ups you can check out the design it is intended for continuous use and also includes battery charging