Home energy monitoring with BS2
jlumens
Posts: 4
Hi!
I would like to build something like a TED or similar to monitor home energy consumption. I have looked around in the forums and have not seen anything utilizing the BS2 for that application. Does anybody have anything like that already developed that I could use as a starting point?
For hardware:
* I will have a number of analog temperature inputs (LM34?) that I need to be monitoring, most inside but also one outside. I think that there is a way to monitor all using a "multiplexer" (?) and just use one set of controller input pins. Is that true, and, if so, do you have a multiplexer and/or multiplexer circuit and/or multiplexer code that you have had success with?
* Do you have a suggestion on how to acquire the electricity input into the house? I'm thinking of something like a clamp-on ammeter type of device.
* I also would like to log energy consumption by my two biggest loads, heat pump and water heater, and will need to find a way to pick up their usage as well. At the very least I would like to know when they are on and off, if I am not able to log their actual consumption. I could probably use the meter outside to determine an average rate for each whe running and then use it as a constant if I knew the start/stop times.
Thank you very much for your help. I am fairly new to all this and want to learn but I don't want to reinvent all of the wheels.
Julia
I would like to build something like a TED or similar to monitor home energy consumption. I have looked around in the forums and have not seen anything utilizing the BS2 for that application. Does anybody have anything like that already developed that I could use as a starting point?
For hardware:
* I will have a number of analog temperature inputs (LM34?) that I need to be monitoring, most inside but also one outside. I think that there is a way to monitor all using a "multiplexer" (?) and just use one set of controller input pins. Is that true, and, if so, do you have a multiplexer and/or multiplexer circuit and/or multiplexer code that you have had success with?
* Do you have a suggestion on how to acquire the electricity input into the house? I'm thinking of something like a clamp-on ammeter type of device.
* I also would like to log energy consumption by my two biggest loads, heat pump and water heater, and will need to find a way to pick up their usage as well. At the very least I would like to know when they are on and off, if I am not able to log their actual consumption. I could probably use the meter outside to determine an average rate for each whe running and then use it as a constant if I knew the start/stop times.
Thank you very much for your help. I am fairly new to all this and want to learn but I don't want to reinvent all of the wheels.
Julia
Comments
A split core current transformer would allow you to measure the current draw and provide isolation. The details of how to connect this to a Stamp depends on the details of the transformer, but would probably require a bridge rectifier and filter capacitor, then maybe a voltage divider to reduce the voltage to something the ADC could handle.
You'll need a real-time clock, something like a DS1302 or DS1307. There are newer devices that include a crystal in the package, but these older devices work well too.
You might consider using a BS2p or BS2px rather than a BS2. These have built-in I2C and 1-Wire support which helps if you want to use an I2C-based real-time clock. With the 1-Wire support, you can also use 1-Wire temperature sensors like the DS18B20 which communicate digitally with the Stamp.
The multichannel ADC looks perfect, and the coding seems really straight forward.
Actually, I just now (literally) ordered a Professional Development Board and a BS2p40 so I should be ok there. If I knew about the ADC an hour ago it would be in the same shipment. It's probably too late for that now, however.
I already have a DS1302 and there is a clock on the PDB, I think. I wouldn't mind upgrading the DS1302 on another board however. I never was too happy with that little separate crystal. Do you have a recommendation for a replacement?
The split core transformer also looks pretty good but I haven't had a chance to study the cut sheet.