There may be an interlock between this and the stand-alone code above to help avoid clashes. This may continue to be used to gather stats beyond those needed for the power management function.įinally I will aim to integrate the MODBUS code into the powermng code. Then I will probably put together a stand-alone C or C++ program to access the SS-MPPT-15L from the RPi. I will first try out the connection to the SS-MPPT-15L from a Windows laptop using Morningstar's MS View application to try to maximise the chance of success. (Possibly I should sheathe the cable with something UV resistant to protect the 1m or so outside, exposed to direct sunlight.) To reach directly from my RPi to the battery bank. Got slightly spendy on aĥm FTDI USB 2.0 Cable Male USB to Male RS232 (Minutes after finally relenting and buying the Meterbus RS232 adapter that I had been considering for years, and working out how to interface it to USB for my RPi for example, I noticed that there is a USB version of the Meterbus adapter which would be simpler and probably more power efficient. The are various solutions for having the RPi talk MODBUS to the SS-MPPT-15L though I may prefer to keep everything in C for efficiency and use the LGPL This should also allow measuring (some of) the power flow into the bank, and out to the loads. This should largely eliminate the effects of voltage drops in the supply cables when estimating SoC (leaving genuine sag from the battery bank itself). : I will try to measure battery voltage at the battery using the SS-MPPT-15L controller over MODBUS over RS232. Off-grid schematic with revisions/snapshots.Off-Grid Stats from the RPi powermng Utility.A Note On Setting Up the Raspberry Pi 2 as Server/Hub.Expanding and Optimising the Off-grid PV System for Mid-winter.Normally the build tools are installed on Raspberry Pi OS, however the git executable is not. To run the above software, you will need to download the source code from the GitHub repository and compile it. Initialising INA228 at addr 0x40 on /dev/i2c-1 Initialising INA226 at addr 0x40 on /dev/i2c-1 The source code is available, so you can easily customise it to your own application. ![]() Not only does it support a wider voltage range, it will accumulate energy and charge – so you don’t have too in software.īelow is the example output you can expect when executing the software. But, It does not accumulate current or charge in hardware.įor more demanding applications like 48V battery banks, we have been using the INA228. It accurately measures current and voltage to derive instantaneous power. The INA226, with a maximum voltage of 36V is perfect for the less challenging 12V battery application. INA228 – 85V, 20-bit, ultra-precise, I2C output current/voltage/power/energy/charge monitor. ![]()
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