A USB-c PD UPS?
The text below has been a part of my workshop blog for a while now but people around me have been pressuring me to publish it to the public. I'm still not sure it is a good idea, but here it is.
The first idea was small. My raspberry pi zero w could be powered from a USB power bank. ...could the powerbank be charged at the same time, making it a tiny uninterruptible power supply (UPS)? The size of the idea was restricted by the fact that the zero uses a microUSB connector for power. But in my head I expanded the idea sideways to other units as well. The petite 802.11n router (gl-ar300m) that shared the internet connection to the household was also powered through microUSB.
Well, those two use cases would be easily solved for my dream of some day living in an #offgrid #tinyhouse.
For that future home I also dreamed of having solar panels powering a bank of batteries. The stored energy would be controlled by a computer that would be powered by the battery bank it was monitoring. The small household would be on a solar UPS, sort of.
The new USB standards have much higher output and even powers my ARM-based laptop. A 60 watt power delivery (PD) unit seems to be enough at this time. At my holiday hut there's a small 12 volt solar system with smaller PD unit. All my mobile units can now be charged or directly powered from those PD units.
Here at my apartment I've been trying out some low-power LEDs for lighting. The one meter strips are powered by USB, something I was a bit surprised by when returning home from IKEA. But the strips only consume about 1.5 watts each so it is quite logical, I guess.
The hair and beard trimmer I use for not looking completely neolithic has a lithium battery good enough for about an hour of defuzzying work. It would follow me to the future tinyhouse if it could be charged from USB. The unit I will need to find will have to be equipped with a USB-c socket...
With the latest USB standards my two ideas can be combined into one system. The large solar batterybank could be 48 volts. It would allow me to charge the #bakfiets as well as the few necessary electronic devices that the household needs.
Now I need to figure out a way to make all of this modular enough.
USB 3.1 Power Delivery offers...
Increased power levels from existing USB standards up to 240W. New 28V, 36V, and 48V fixed voltages enable up to 140W, 180W and 240W power levels, respectively.
An adjustable voltage supply mode allows the device being powered an ability to request intermediate voltages between 15V and up to the maximum available fixed voltage of the charger.
Power direction is no longer fixed. This enables the product with the power (Host or Peripheral) to provide the power.
Optimize power management across multiple peripherals by allowing each device to take only the power it requires, and to get more power when required for a given application.
Intelligent and flexible system level management of power via optional hub communication with the PC.
Allows low power cases such as headsets to negotiate for only the power they require.