These pictures show the current state of the Arduino-Shield. In the picture below you see what components will be combined onto a custom PCB. The MOSFETs can continuously switch 50A @ 30V, the Relay is rated for 10A @ 120V and the Transformer delivers 0.8A @ 24V to power/charge equipment.
The ATMega2560 is below the bread-board which is sitting on a proto-shield. The custom PCB will hold all components and the ATMega as well. The final PCB will have the Arduinio-Shield connectors so you can also run your own code and extend it with all available Arduinio-Shield boards.
The Display is a simple 16×2 character display with an RGB background light. The display is optional and connected via a header pin. It shows the essential state of the UPS. The first row is fixed and the second can scroll all sensors values consecutively. Not shown are 2 push buttons below the display and a “mode” switch. The RGB background light of the display is used for green-yellow-red State-Of-Charge (SOC) and blinks for warnings. There is also a buzzer on board which is used for acoustical warnings.
The code that currently runs implements the following features:
- “virtual fuse” for over current protection
- short circuit sensing
- Temperature sensor avoiding over heating
- SOC meter using coulomb counting
- phase sync for seamless switching
- lifetime kWh counter
The current revision of the code runs for several months now and will hopefully only see minor changes. This is the list of all analog and digital inputs that will be on the board:
- 2x DC current (hall) sensor 50A bi-directional
- 2x DC voltage
- 2x AC voltage
- 1x Temperature sensor
- 3x pushbuttons
- 1x 3 position slider switch
On the output side:
- 1x ON/OFF for DPDT AC relay
- 1x PWM for MOSFETs
- 1x PWM for buzzer
- 1x PWM for charger
- 3x PWM for RGB display backlight
(The display will have its own header pin connector)
Right now I am waiting on Mike from Athens to finish the schematics and do the layout for the print. If you are interested in testing an early version of the PCB for free please contact me – I am happy for any suggestions to improve the design or add compatibility – (send email or leave a comment).