Solar Charging Android Phone Outside

I'm trying to keep an Android phone charged off of a solar panel outdoors. The phone will always be outside.

I've looked at the portable USB solar chargers; however, I don't think those will work for my scenario. Most of the ones I've seen require an occasional wall charge. The Android phone will only be running one app which will be a custom BLE scanner (and whatever Android runs in the foreground).

Does anyone have suggestions what I would need to use to keep the phone charged outdoors? This project will be my first solar one. I'd like it to be a reasonably affordable solution, and if possible as small solar panel as possible to keep things running.


What does this have to do with Arduino?


I know it's a bit of a long shot, but the community here is incredible. I just thought I'd at least try and see if anyone could help. Or if anyone knows of a more suitable forum.

The Android phone is part of my Arduino project. The Arduino devices will be communicating with it :slight_smile:

This isnt as easy as it sounds.
Mobile phone chargers produce 5V and need to be able to source at least 500 ma depending a bit on the type of phone .
You will need to figure out how much energy the phone uses over a 24 H period, and from this and your latitude you can figure out how big the Solar panel has to be.
Then you will need some kind of battery for the Solar Panel to charge, some kind of regulator to ensure the battery isnt over or undercharged, and some method of creating the 5V .
Mobile phones can be power hungry as they are running a high speed ARM cpu.

This was the exact answer I was looking for. It sounds like I may need to bite the bullet and just code the gateway on an Arduino. The power consumption on either an Android Phone or Raspberry Pi is just too much for what I'm trying to do. I would end up power cycling the Pi anyways.

I was trying to use a higher level abstraction in code (SQLite for offline storage, JSON libraries, etc.), but maybe the dual core ESP32 will do the job. With an RTC, some FRAM, and some patience... it may work out better. Thank you.

I can't quantify it without testing, but I doubt power draw on an Android phone with everything but bluetooth shut off is all that high. I'd expect it could run for days off of the phone's battery (say ~2000 mAh @ 3.7V) so a solar charger specified to charge the phone in a day ought to be able to keep up.

I've done a number of projects with Android phones with only wifi running and they'll run a day on battery and BLE should be less power hungry. Android power management is worlds better than Raspberry Pi/Raspbian.

I'll definitely test out how long the battery will last. I failed to mention the Android device will be acting as a gateway (WiFi and BLE). So, I think in the long run for my case, the ESP32 is a good choice.

The price we pay for low power. I honestly had no idea until I started doing MCU stuff.

ESP32 certainly seems like a reasonable approach for your project as I understand it.

In comparison the Android approach seems like it can be done entirely with off the shelf components and software whereas the ESP32 approach is perhaps a more elegant/optimized final solution at the cost of more involved hardware engineering and fabrication to get a system power solution. It's a hobby project (I presume) so there isn't a wrong approach as long as it results in a viable solution.

Absolutely agree and thank you for the feedback! I may end up going back to Android depending on how much effort it takes to get an ESP32 gateway up and running.

It's a hobby project (I presume)

It's starting off as a hobby, but my hope it will turn into something else. Not exactly sure what yet, but we'll see :slight_smile: