Keep the things charged

Periodically recharge multiple things for emergency preparedness

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This project will create a charger to efficiently maintain the battery on multiple USB powered things so they are ready for use in an emergency. Things like power banks, vehicle jump starters, rechargeable batteries and old cell phones that aren’t used routinely are the targeted devices. The charger will sequentially power each connected thing periodically to maintain a full charge. A self-contained user interface is envisioned to allow the frequency and duration of charge cycles to be configured as well as an on demand option to full recharge selected things.

Project currently in concept state.

Here are design thoughts:

  • Provide some type A female ports to allow flexibility in which things can be connected
  • Repurpose old USB/Lightning/Barrel Jack cables to provide a hardwired connection
  • LED to show what port is selected / charging.
  • Dev board with integrated screen and buttons for user interface
  • Monitor current to each thing over time, detect and report abnormalities
  • Prevent discharge of thing back into charger
  • Evaluate input power requirements, support wider DC range or just a 5V input.

This project address the effort required to keep multiple devices ready for use in an emergency (as well as items not used on a daily basis).  The battery pack jump starter sitting on a shelf in the garage unplugged won't be ready to use when the battery in your car is flat.  Keeping it plugged in 24/7  to a charger adds an unnecessary vampire load to your electric usage.  This project will provide a device that efficiently maintains the battery charge on multiple devices while minimizing effort and power usage to do so.

While basic functionality can be provided without internet connection, a connection would allow for reminders to be sent when an emergency device has been unplugged for a prolonged period or is taking higher than baseline current to recharge.  This would address forgetting to return a device to the charger after use, for instance the half charged power banks a suitcase.

A wall mounted device is envisioned with usb ports and/or cables along the bottom face of the case.  A status LED will be provided for each port/cable.  This will allow the device to be mounted at the back of a shelf with all of the things being charged sitting on the shelf.  An ESP32 based dev board with integral LCD seems like a good choice for the project.  Arduino framework will be used to program the ESP32, the custom code will be released under MIT License.  KiCad will be used for PCB design and design files released under CERN OHL.

  • Block Diagram

    mulcmu09/03/2022 at 00:25 0 comments

    Not much to it.  Keeping design simple and robust without a lot of scope creep.

  • Will it ~charge?

    mulcmu08/19/2022 at 01:24 0 comments

    I setup a USB breakout board with 5V & GND and nothing on the data lines to see what battery powered USB devices I could find that would still charge.  I was expecting to need at least some resistors on the data lines but so far everything I've tried to charge has worked, even a few USB-C phones.  So now I'm scouring house looking for any other devices to test to see if it won't charge.

    I was looking to order some charging port ICs for testing but looks like these will not be necessary.  Simple mosfet to switch top off each device periodically will keep things simple and cheap.

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